[PATCH v3 00/16] mm: Some cleanups for page allocator APIs

[PATCH v3 00/16] mm: Some cleanups for page allocator APIs

[Brendan Jackman]

This is based on mm-new, it depends on moving alloc_tag to mm/ [0].

[0] https://lore.kernel.org/all/aj5QBtJcphPElczI@lucifer/

Some tweaks and cleanups for page allocator entrypoint and flags. This
is motivated by preparation for __GFP_UNMAPPED [1] (which will probably
become ALLOC_UNMAPPED in its next iteration), but all this is supposed
to be an improvement to the codebase in its own right: unifying code
paths, reducing API surface, and removing GFP flags.

[1] https://lore.kernel.org/all/20260320-page_alloc-unmapped-v2-0-28bf1bd54f41@google.com/

This started with unifying  __alloc_frozen_pages[_nolock]_noprof() and
expanded from there.

Unifying the nolock allocator entrypoint with the normal allocator
entrypoint means adding an alloc_flags argument to the later (only
exposed within mm/). This presents an opportunity to take advantage of
that arg to remove some GFP flags, if we add that alloc_flags arg a bit
more broadly to allocator entrypoints.

To distinguish between mm-internal and "public" allocator entrypoints,
it makes sense to use the __ prefix. There are already some public APIs
with that prefix. For *alloc_pages*, just removing those variants seems
like a nice cleanup anyway, so do that. For get_free_pages, the "__"
variant is the _only_ variant and it's very widely used, so it doesn't
seem worthwhile to modify that. Therefore, scope this "__" change
specifically to the *alloc_pages* API, which means we leave the
*folio_alloc* API untouched too, even though that could probably be
cleaned up if so desired.

Tested:

- KVM, mm, and BPF selftests in a QEMU VM

- kunit.py on x86_64

- For the ALLOC_NO_CODETAG bits I just booted a VM and read
  /proc/allocinfo. I confirmed that if I remove ALLOC_NO_CODETAG, the
  kernel crashes in early boot, so I was at least booting code that
  depends on this logic.

I used Google's internal version of Antigravity (AI coding harness) to
do the repetitive bits, those commits are marked with Assisted-by, the
rest is manual.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
Changes in v3:
- Created mm/page_alloc.h
- Fixed EXPORT_SYMBOL() issues
- Reworded commit messages per Sashiko's pointers
- Dropped rename of alloc_flags arg in prepare_alloc_pages() (Suren)
- Renamed gfp_to_alloc_flags_nonblocking() too after rebasing onto:
  https://lore.kernel.org/all/20260623004600.113347-1-jp.kobryn@linux.dev/
- Link to v2: https://patch.msgid.link/20260622-alloc-trylock-v2-0-31f31367d420@google.com

Changes in v2:
- Fixed up whitespace in nolock unification patch
- Introduced ALLOC_DEFAULT to replace literal 0 for alloc_flags
- All other patches are new
- Link to v1: https://patch.msgid.link/20260617-alloc-trylock-v1-1-83fd7858832e@google.com

---
Brendan Jackman (16):
      mm/page_alloc: rename ALLOC_TRYLOCK -> ALLOC_NOLOCK
      mm/page_alloc: some renames to clarify alloc_flags scopes
      mm: name some args in a function declaration
      mm: Split out internal page_alloc.h
      mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()
      mm/page_alloc: relax GFP WARN in nolock allocs
      mm: move some stuff to mm/page_alloc.h
      perf/x86/intel: Use higher-level allocator API
      KVM: VMX: Use higher-level allocator API
      x86/virt: Use higher-level allocator API
      sgi-xp: Use higher-level allocator API
      net/funeth: Switch to higher-level allocator API
      mm: Remove __alloc_pages_node()
      mm: Move __alloc_pages() to mm/page_alloc.h
      mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG
      mm: remove the __GFP_NO_OBJ_EXT flag

 Documentation/admin-guide/cgroup-v1/cpusets.rst  |   2 +-
 Documentation/admin-guide/mm/transhuge.rst       |   2 +-
 MAINTAINERS                                      |   1 +
 arch/x86/events/intel/ds.c                       |   6 +-
 arch/x86/kvm/vmx/vmx.c                           |   2 +-
 arch/x86/virt/hw.c                               |   2 +-
 drivers/misc/sgi-xp/xpc_uv.c                     |   2 +-
 drivers/net/ethernet/fungible/funeth/funeth_rx.c |   2 +-
 include/linux/gfp.h                              |  54 +---
 mm/alloc_tag.c                                   |  22 +-
 mm/compaction.c                                  |   5 +-
 mm/hugetlb.c                                     |   4 +-
 mm/internal.h                                    | 253 ------------------
 mm/khugepaged.c                                  |   1 +
 mm/memory-failure.c                              |   1 +
 mm/memory_hotplug.c                              |   1 +
 mm/mempolicy.c                                   |  11 +-
 mm/mm_init.c                                     |   1 +
 mm/page_alloc.c                                  | 259 ++++++++++---------
 mm/page_alloc.h                                  | 316 +++++++++++++++++++++++
 mm/page_frag_cache.c                             |   6 +-
 mm/page_isolation.c                              |   1 +
 mm/page_owner.c                                  |   2 +-
 mm/show_mem.c                                    |   1 +
 mm/slub.c                                        |   7 +-
 mm/swap.c                                        |   1 +
 mm/vmscan.c                                      |   1 +
 mm/vmstat.c                                      |   1 +
 tools/include/linux/gfp_types.h                  |   7 -
 29 files changed, 506 insertions(+), 468 deletions(-)
---
base-commit: ec005628e9dbcef26b761fa860f264fe6e5fd690
change-id: 20260617-alloc-trylock-14ad37dab337

Best regards,
--  
Brendan Jackman <jackmanb@google.com>

[PATCH v3 01/16] mm/page_alloc: rename ALLOC_TRYLOCK -> ALLOC_NOLOCK

[Brendan Jackman]

It's confusing that the function is called "nolock" but the flag is
called "trylock", align them.

The function's terminology is more visible and has more mindshare so use that.

Suggested-by: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
Link: https://lore.kernel.org/linux-mm/2399b3ad-4eac-4a14-94c3-27e9f07972a1@kernel.org/
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 mm/internal.h   |  2 +-
 mm/page_alloc.c | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 430aa72a45758..2237eee030cba 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1480,7 +1480,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
 #define ALLOC_NOFRAGMENT	  0x0
 #endif
 #define ALLOC_HIGHATOMIC	0x200 /* Allows access to MIGRATE_HIGHATOMIC */
-#define ALLOC_TRYLOCK		0x400 /* Only use spin_trylock in allocation path */
+#define ALLOC_NOLOCK		0x400 /* Only use spin_trylock in allocation path */
 #define ALLOC_KSWAPD		0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */
 
 /* Flags that allow allocations below the min watermark. */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 62f71ece7ca17..421271849f291 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2530,7 +2530,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 	unsigned long flags;
 	int i;
 
-	if (unlikely(alloc_flags & ALLOC_TRYLOCK)) {
+	if (unlikely(alloc_flags & ALLOC_NOLOCK)) {
 		if (!spin_trylock_irqsave(&zone->lock, flags))
 			return 0;
 	} else {
@@ -3218,7 +3218,7 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone,
 
 	do {
 		page = NULL;
-		if (unlikely(alloc_flags & ALLOC_TRYLOCK)) {
+		if (unlikely(alloc_flags & ALLOC_NOLOCK)) {
 			if (!spin_trylock_irqsave(&zone->lock, flags))
 				return NULL;
 		} else {
@@ -5059,7 +5059,7 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 	 * Don't invoke should_fail logic, since it may call
 	 * get_random_u32() and printk() which need to spin_lock.
 	 */
-	if (!(*alloc_flags & ALLOC_TRYLOCK) &&
+	if (!(*alloc_flags & ALLOC_NOLOCK) &&
 	    should_fail_alloc_page(gfp_mask, order))
 		return false;
 
@@ -7804,7 +7804,7 @@ static bool cond_accept_memory(struct zone *zone, unsigned int order,
 		return false;
 
 	/* Bailout, since try_to_accept_memory_one() needs to take a lock */
-	if (alloc_flags & ALLOC_TRYLOCK)
+	if (alloc_flags & ALLOC_NOLOCK)
 		return false;
 
 	wmark = promo_wmark_pages(zone);
@@ -7896,7 +7896,7 @@ struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned
 	 */
 	gfp_t alloc_gfp = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC | __GFP_COMP
 			| gfp_flags;
-	unsigned int alloc_flags = ALLOC_TRYLOCK;
+	unsigned int alloc_flags = ALLOC_NOLOCK;
 	struct alloc_context ac = { };
 	struct page *page;
 

-- 
2.54.0

Re: [PATCH v3 01/16] mm/page_alloc: rename ALLOC_TRYLOCK -> ALLOC_NOLOCK

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> It's confusing that the function is called "nolock" but the flag is
> called "trylock", align them.
> 
> The function's terminology is more visible and has more mindshare so use that.
> 
> Suggested-by: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
> Link: https://lore.kernel.org/linux-mm/2399b3ad-4eac-4a14-94c3-27e9f07972a1@kernel.org/
> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

[PATCH v3 02/16] mm/page_alloc: some renames to clarify alloc_flags scopes

[Brendan Jackman]

It's pretty confusing that:

- The slowpath and fastpath have a totally distinct set of alloc_flags.

- gfp_to_alloc_flags() sounds generic but it only influences the
  slowpath.

Rename some variables to highlight which alloc_flags are
fastpath-specific. Rename gfp_to_alloc_flags() to highlight that it's
slowpath-specific.

gfp_to_alloc_flags_cma() and gfp_to_alloc_flags_nonblocking() currently
have perfectly harmless names, but to keep the naming consistent also
rename those to the alloc_flags_*() pattern (which already exists for
alloc_flags_nofragment()).

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 mm/page_alloc.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 421271849f291..6010693861ec2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3774,8 +3774,8 @@ alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
 }
 
 /* Must be called after current_gfp_context() which can change gfp_mask */
-static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
-						  unsigned int alloc_flags)
+static inline unsigned int alloc_flags_cma(gfp_t gfp_mask,
+					   unsigned int alloc_flags)
 {
 #ifdef CONFIG_CMA
 	if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
@@ -4474,7 +4474,7 @@ static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
 }
 
 static inline unsigned int
-gfp_to_alloc_flags_nonblocking(gfp_t gfp_mask, unsigned int order)
+alloc_flags_nonblocking(gfp_t gfp_mask, unsigned int order)
 {
 	unsigned int alloc_flags = 0;
 
@@ -4497,7 +4497,7 @@ gfp_to_alloc_flags_nonblocking(gfp_t gfp_mask, unsigned int order)
 }
 
 static inline unsigned int
-gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
+alloc_flags_slowpath(gfp_t gfp_mask, unsigned int order)
 {
 	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
 
@@ -4512,7 +4512,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
 	if (gfp_mask & __GFP_KSWAPD_RECLAIM)
 		alloc_flags |= ALLOC_KSWAPD;
 
-	alloc_flags |= gfp_to_alloc_flags_nonblocking(gfp_mask, order);
+	alloc_flags |= alloc_flags_nonblocking(gfp_mask, order);
 
 	if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
 		/*
@@ -4525,7 +4525,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
 	} else if (unlikely(rt_or_dl_task(current)) && in_task())
 		alloc_flags |= ALLOC_MIN_RESERVE;
 
-	alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
+	alloc_flags = alloc_flags_cma(gfp_mask, alloc_flags);
 
 	if (defrag_mode)
 		alloc_flags |= ALLOC_NOFRAGMENT;
@@ -4791,7 +4791,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	 * kswapd needs to be woken up, and to avoid the cost of setting up
 	 * alloc_flags precisely. So we do that now.
 	 */
-	alloc_flags = gfp_to_alloc_flags(gfp_mask, order);
+	alloc_flags = alloc_flags_slowpath(gfp_mask, order);
 
 	/*
 	 * We need to recalculate the starting point for the zonelist iterator
@@ -4832,7 +4832,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
 	if (reserve_flags)
-		alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags) |
+		alloc_flags = alloc_flags_cma(gfp_mask, reserve_flags) |
 					  (alloc_flags & ALLOC_KSWAPD);
 
 	/*
@@ -5063,7 +5063,7 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 	    should_fail_alloc_page(gfp_mask, order))
 		return false;
 
-	*alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags);
+	*alloc_flags = alloc_flags_cma(gfp_mask, *alloc_flags);
 
 	/* Dirty zone balancing only done in the fast path */
 	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
@@ -5277,7 +5277,7 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 		int preferred_nid, nodemask_t *nodemask)
 {
 	struct page *page;
-	unsigned int alloc_flags = ALLOC_WMARK_LOW;
+	unsigned int fastpath_alloc_flags = ALLOC_WMARK_LOW;
 	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
 	struct alloc_context ac = { };
 
@@ -5299,18 +5299,18 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 	gfp = current_gfp_context(gfp);
 	alloc_gfp = gfp;
 	if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
-			&alloc_gfp, &alloc_flags))
+			&alloc_gfp, &fastpath_alloc_flags))
 		return NULL;
 
 	/*
 	 * Forbid the first pass from falling back to types that fragment
 	 * memory until all local zones are considered.
 	 */
-	alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
-	alloc_flags |= gfp_to_alloc_flags_nonblocking(gfp, order) & ALLOC_HIGHATOMIC;
+	fastpath_alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
+	fastpath_alloc_flags |= alloc_flags_nonblocking(gfp, order) & ALLOC_HIGHATOMIC;
 
 	/* First allocation attempt */
-	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
+	page = get_page_from_freelist(alloc_gfp, order, fastpath_alloc_flags, &ac);
 	if (likely(page))
 		goto out;
 

-- 
2.54.0

Re: [PATCH v3 02/16] mm/page_alloc: some renames to clarify alloc_flags scopes

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> It's pretty confusing that:
> 
> - The slowpath and fastpath have a totally distinct set of alloc_flags.
> 
> - gfp_to_alloc_flags() sounds generic but it only influences the
>   slowpath.
> 
> Rename some variables to highlight which alloc_flags are
> fastpath-specific. Rename gfp_to_alloc_flags() to highlight that it's
> slowpath-specific.
> 
> gfp_to_alloc_flags_cma() and gfp_to_alloc_flags_nonblocking() currently
> have perfectly harmless names, but to keep the naming consistent also
> rename those to the alloc_flags_*() pattern (which already exists for
> alloc_flags_nofragment()).

How annoying that alloc_flags_nofragment() doesn't have gfp as the first
parameter, unlike others.
Oh well, must resist too much OCD :)

Uh, more annoyingly, alloc_flags_cma() takes alloc_flags and returns
augmented alloc flags, so there's stuff like

*alloc_flags = alloc_flags_cma(gfp_mask, *alloc_flags);

Since we're unifying, it could be make to work additively like others? Then:

*alloc_flags |= alloc_flags_cma(gfp_mask);

> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Otherwise, LGTM.
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

Re: [PATCH v3 02/16] mm/page_alloc: some renames to clarify alloc_flags scopes

[Brendan Jackman]

On Tue Jun 30, 2026 at 12:38 PM UTC, Vlastimil Babka (SUSE) wrote:
> On 6/29/26 15:11, Brendan Jackman wrote:
>> It's pretty confusing that:
>> 
>> - The slowpath and fastpath have a totally distinct set of alloc_flags.
>> 
>> - gfp_to_alloc_flags() sounds generic but it only influences the
>>   slowpath.
>> 
>> Rename some variables to highlight which alloc_flags are
>> fastpath-specific. Rename gfp_to_alloc_flags() to highlight that it's
>> slowpath-specific.
>> 
>> gfp_to_alloc_flags_cma() and gfp_to_alloc_flags_nonblocking() currently
>> have perfectly harmless names, but to keep the naming consistent also
>> rename those to the alloc_flags_*() pattern (which already exists for
>> alloc_flags_nofragment()).
>
> How annoying that alloc_flags_nofragment() doesn't have gfp as the first
> parameter, unlike others.
> Oh well, must resist too much OCD :)
>
> Uh, more annoyingly, alloc_flags_cma() takes alloc_flags and returns
> augmented alloc flags, so there's stuff like
>
> *alloc_flags = alloc_flags_cma(gfp_mask, *alloc_flags);
>
> Since we're unifying, it could be make to work additively like others? Then:
>
> *alloc_flags |= alloc_flags_cma(gfp_mask);

Sure, I can chuck this on as an extra patch.

[PATCH v3 03/16] mm: name some args in a function declaration

[Brendan Jackman]

Checkpatch complains about this, a later patch will move the code, fix
it so that checkpatch doesn't complain about that patch. Do it in a
separate patch so the "move the code" patch is trivial to review using
Git's diff colouring.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 mm/internal.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 2237eee030cba..8ce59c5664497 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -919,8 +919,8 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
 
 extern int user_min_free_kbytes;
 
-struct page *__alloc_frozen_pages_noprof(gfp_t, unsigned int order, int nid,
-		nodemask_t *);
+struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
+		nodemask_t *nodemask);
 #define __alloc_frozen_pages(...) \
 	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
 void free_frozen_pages(struct page *page, unsigned int order);

-- 
2.54.0

Re: [PATCH v3 03/16] mm: name some args in a function declaration

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> Checkpatch complains about this, a later patch will move the code, fix
> it so that checkpatch doesn't complain about that patch. Do it in a
> separate patch so the "move the code" patch is trivial to review using
> Git's diff colouring.
> 
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

> ---
>  mm/internal.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/internal.h b/mm/internal.h
> index 2237eee030cba..8ce59c5664497 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -919,8 +919,8 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
>  
>  extern int user_min_free_kbytes;
>  
> -struct page *__alloc_frozen_pages_noprof(gfp_t, unsigned int order, int nid,
> -		nodemask_t *);
> +struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
> +		nodemask_t *nodemask);
>  #define __alloc_frozen_pages(...) \
>  	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
>  void free_frozen_pages(struct page *page, unsigned int order);
> 

[PATCH v3 04/16] mm: Split out internal page_alloc.h

[Brendan Jackman]

internal.h is a bit bloated, seems like time for a page_alloc.h.

Where it wasn't obvious, the heuristic for deciding what goes into this
new header was "does it support/correspond to a definition in
mm/page_alloc.c?"

Only need to include it from 15 .c files out of 164 so this does seem
like a genuine reduction in scopes, which is nice. And there's no
circular internal.h<->page_alloc.h dependency, so it seems worthwhile to
split this up before that inevitably emerges!

Suggested-by: "David Hildenbrand (Arm)" <david@kernel.org>
Link: https://lore.kernel.org/all/41e92bab-6882-401a-8de9-154adbdcfb36@kernel.org/
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 MAINTAINERS          |   1 +
 mm/compaction.c      |   1 +
 mm/hugetlb.c         |   1 +
 mm/internal.h        | 252 -----------------------------------------------
 mm/khugepaged.c      |   1 +
 mm/memory-failure.c  |   1 +
 mm/memory_hotplug.c  |   1 +
 mm/mempolicy.c       |   1 +
 mm/mm_init.c         |   1 +
 mm/page_alloc.c      |   1 +
 mm/page_alloc.h      | 269 +++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/page_frag_cache.c |   2 +-
 mm/page_isolation.c  |   1 +
 mm/page_owner.c      |   2 +-
 mm/show_mem.c        |   1 +
 mm/slub.c            |   1 +
 mm/swap.c            |   1 +
 mm/vmscan.c          |   1 +
 18 files changed, 285 insertions(+), 254 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index f55cc75801f4c..978a04e1f7cc3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17171,6 +17171,7 @@ F:	mm/debug_page_alloc.c
 F:	mm/debug_page_ref.c
 F:	mm/fail_page_alloc.c
 F:	mm/page_alloc.c
+F:	mm/page_alloc.h
 F:	mm/page_ext.c
 F:	mm/page_frag_cache.c
 F:	mm/page_isolation.c
diff --git a/mm/compaction.c b/mm/compaction.c
index f08765ade014c..7d80735502d9a 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -24,6 +24,7 @@
 #include <linux/page_owner.h>
 #include <linux/psi.h>
 #include <linux/cpuset.h>
+#include "page_alloc.h"
 #include "internal.h"
 
 #ifdef CONFIG_COMPACTION
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index fb7ad2a4a26b4..f7925624c4d2e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -47,6 +47,7 @@
 #include <linux/node.h>
 #include <linux/page_owner.h>
 #include "internal.h"
+#include "page_alloc.h"
 #include "hugetlb_vmemmap.h"
 #include "hugetlb_cma.h"
 #include "hugetlb_internal.h"
diff --git a/mm/internal.h b/mm/internal.h
index 8ce59c5664497..c22284f04fc9e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -658,165 +658,6 @@ extern int defrag_mode;
 void setup_per_zone_wmarks(void);
 void calculate_min_free_kbytes(void);
 int __meminit init_per_zone_wmark_min(void);
-void page_alloc_sysctl_init(void);
-
-/*
- * Structure for holding the mostly immutable allocation parameters passed
- * between functions involved in allocations, including the alloc_pages*
- * family of functions.
- *
- * nodemask, migratetype and highest_zoneidx are initialized only once in
- * __alloc_pages() and then never change.
- *
- * zonelist, preferred_zone and highest_zoneidx are set first in
- * __alloc_pages() for the fast path, and might be later changed
- * in __alloc_pages_slowpath(). All other functions pass the whole structure
- * by a const pointer.
- */
-struct alloc_context {
-	struct zonelist *zonelist;
-	const nodemask_t *nodemask;
-	struct zoneref *preferred_zoneref;
-	int migratetype;
-
-	/*
-	 * highest_zoneidx represents highest usable zone index of
-	 * the allocation request. Due to the nature of the zone,
-	 * memory on lower zone than the highest_zoneidx will be
-	 * protected by lowmem_reserve[highest_zoneidx].
-	 *
-	 * highest_zoneidx is also used by reclaim/compaction to limit
-	 * the target zone since higher zone than this index cannot be
-	 * usable for this allocation request.
-	 */
-	enum zone_type highest_zoneidx;
-	bool spread_dirty_pages;
-};
-
-/*
- * This function returns the order of a free page in the buddy system. In
- * general, page_zone(page)->lock must be held by the caller to prevent the
- * page from being allocated in parallel and returning garbage as the order.
- * If a caller does not hold page_zone(page)->lock, it must guarantee that the
- * page cannot be allocated or merged in parallel. Alternatively, it must
- * handle invalid values gracefully, and use buddy_order_unsafe() below.
- */
-static inline unsigned int buddy_order(struct page *page)
-{
-	/* PageBuddy() must be checked by the caller */
-	return page_private(page);
-}
-
-/*
- * Like buddy_order(), but for callers who cannot afford to hold the zone lock.
- * PageBuddy() should be checked first by the caller to minimize race window,
- * and invalid values must be handled gracefully.
- *
- * READ_ONCE is used so that if the caller assigns the result into a local
- * variable and e.g. tests it for valid range before using, the compiler cannot
- * decide to remove the variable and inline the page_private(page) multiple
- * times, potentially observing different values in the tests and the actual
- * use of the result.
- */
-#define buddy_order_unsafe(page)	READ_ONCE(page_private(page))
-
-/*
- * This function checks whether a page is free && is the buddy
- * we can coalesce a page and its buddy if
- * (a) the buddy is not in a hole (check before calling!) &&
- * (b) the buddy is in the buddy system &&
- * (c) a page and its buddy have the same order &&
- * (d) a page and its buddy are in the same zone.
- *
- * For recording whether a page is in the buddy system, we set PageBuddy.
- * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
- *
- * For recording page's order, we use page_private(page).
- */
-static inline bool page_is_buddy(struct page *page, struct page *buddy,
-				 unsigned int order)
-{
-	if (!page_is_guard(buddy) && !PageBuddy(buddy))
-		return false;
-
-	if (buddy_order(buddy) != order)
-		return false;
-
-	/*
-	 * zone check is done late to avoid uselessly calculating
-	 * zone/node ids for pages that could never merge.
-	 */
-	if (page_zone_id(page) != page_zone_id(buddy))
-		return false;
-
-	VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
-
-	return true;
-}
-
-/*
- * Locate the struct page for both the matching buddy in our
- * pair (buddy1) and the combined O(n+1) page they form (page).
- *
- * 1) Any buddy B1 will have an order O twin B2 which satisfies
- * the following equation:
- *     B2 = B1 ^ (1 << O)
- * For example, if the starting buddy (buddy2) is #8 its order
- * 1 buddy is #10:
- *     B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
- *
- * 2) Any buddy B will have an order O+1 parent P which
- * satisfies the following equation:
- *     P = B & ~(1 << O)
- *
- * Assumption: *_mem_map is contiguous at least up to MAX_PAGE_ORDER
- */
-static inline unsigned long
-__find_buddy_pfn(unsigned long page_pfn, unsigned int order)
-{
-	return page_pfn ^ (1 << order);
-}
-
-/*
- * Find the buddy of @page and validate it.
- * @page: The input page
- * @pfn: The pfn of the page, it saves a call to page_to_pfn() when the
- *       function is used in the performance-critical __free_one_page().
- * @order: The order of the page
- * @buddy_pfn: The output pointer to the buddy pfn, it also saves a call to
- *             page_to_pfn().
- *
- * The found buddy can be a non PageBuddy, out of @page's zone, or its order is
- * not the same as @page. The validation is necessary before use it.
- *
- * Return: the found buddy page or NULL if not found.
- */
-static inline struct page *find_buddy_page_pfn(struct page *page,
-			unsigned long pfn, unsigned int order, unsigned long *buddy_pfn)
-{
-	unsigned long __buddy_pfn = __find_buddy_pfn(pfn, order);
-	struct page *buddy;
-
-	buddy = page + (__buddy_pfn - pfn);
-	if (buddy_pfn)
-		*buddy_pfn = __buddy_pfn;
-
-	if (page_is_buddy(page, buddy, order))
-		return buddy;
-	return NULL;
-}
-
-extern struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
-				unsigned long end_pfn, struct zone *zone);
-
-static inline struct page *pageblock_pfn_to_page(unsigned long start_pfn,
-				unsigned long end_pfn, struct zone *zone)
-{
-	if (zone->contiguous)
-		return pfn_to_page(start_pfn);
-
-	return __pageblock_pfn_to_page(start_pfn, end_pfn, zone);
-}
 
 void set_zone_contiguous(struct zone *zone);
 bool pfn_range_intersects_zones(int nid, unsigned long start_pfn,
@@ -831,8 +672,6 @@ extern int __isolate_free_page(struct page *page, unsigned int order);
 extern void __putback_isolated_page(struct page *page, unsigned int order,
 				    int mt);
 extern void memblock_free_pages(unsigned long pfn, unsigned int order);
-extern void __free_pages_core(struct page *page, unsigned int order,
-		enum meminit_context context);
 
 /*
  * This will have no effect, other than possibly generating a warning, if the
@@ -914,40 +753,6 @@ static inline void init_compound_tail(struct page *tail,
 	prep_compound_tail(tail, head, order);
 }
 
-void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags);
-extern bool free_pages_prepare(struct page *page, unsigned int order);
-
-extern int user_min_free_kbytes;
-
-struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
-		nodemask_t *nodemask);
-#define __alloc_frozen_pages(...) \
-	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
-void free_frozen_pages(struct page *page, unsigned int order);
-void free_unref_folios(struct folio_batch *fbatch);
-
-#ifdef CONFIG_NUMA
-struct page *alloc_frozen_pages_noprof(gfp_t, unsigned int order);
-#else
-static inline struct page *alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order)
-{
-	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL);
-}
-#endif
-
-#define alloc_frozen_pages(...) \
-	alloc_hooks(alloc_frozen_pages_noprof(__VA_ARGS__))
-
-struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order);
-#define alloc_frozen_pages_nolock(...) \
-	alloc_hooks(alloc_frozen_pages_nolock_noprof(__VA_ARGS__))
-void free_frozen_pages_nolock(struct page *page, unsigned int order);
-
-extern void zone_pcp_reset(struct zone *zone);
-extern void zone_pcp_disable(struct zone *zone);
-extern void zone_pcp_enable(struct zone *zone);
-extern void zone_pcp_init(struct zone *zone);
-
 extern void *memmap_alloc(phys_addr_t size, phys_addr_t align,
 			  phys_addr_t min_addr,
 			  int nid, bool exact_nid);
@@ -1101,23 +906,6 @@ static inline void init_cma_pageblock(struct page *page)
 }
 #endif
 
-enum fallback_result {
-	/* Found suitable migratetype, *mt_out is valid. */
-	FALLBACK_FOUND,
-	/* No fallback found in requested order. */
-	FALLBACK_EMPTY,
-	/* Passed @claimable, but claiming whole block is a bad idea. */
-	FALLBACK_NOCLAIM,
-};
-enum fallback_result
-find_suitable_fallback(struct free_area *area, unsigned int order,
-		       int migratetype, bool claimable, int *mt_out);
-
-static inline bool free_area_empty(struct free_area *area, int migratetype)
-{
-	return list_empty(&area->free_list[migratetype]);
-}
-
 /* mm/util.c */
 struct anon_vma *folio_anon_vma(const struct folio *folio);
 
@@ -1445,46 +1233,6 @@ extern unsigned long  __must_check vm_mmap_pgoff(struct file *, unsigned long,
 unsigned long reclaim_pages(struct list_head *folio_list);
 unsigned int reclaim_clean_pages_from_list(struct zone *zone,
 					    struct list_head *folio_list);
-/* The ALLOC_WMARK bits are used as an index to zone->watermark */
-#define ALLOC_WMARK_MIN		WMARK_MIN
-#define ALLOC_WMARK_LOW		WMARK_LOW
-#define ALLOC_WMARK_HIGH	WMARK_HIGH
-#define ALLOC_NO_WATERMARKS	0x04 /* don't check watermarks at all */
-
-/* Mask to get the watermark bits */
-#define ALLOC_WMARK_MASK	(ALLOC_NO_WATERMARKS-1)
-
-/*
- * Only MMU archs have async oom victim reclaim - aka oom_reaper so we
- * cannot assume a reduced access to memory reserves is sufficient for
- * !MMU
- */
-#ifdef CONFIG_MMU
-#define ALLOC_OOM		0x08
-#else
-#define ALLOC_OOM		ALLOC_NO_WATERMARKS
-#endif
-
-#define ALLOC_NON_BLOCK		 0x10 /* Caller cannot block. Allow access
-				       * to 25% of the min watermark or
-				       * 62.5% if __GFP_HIGH is set.
-				       */
-#define ALLOC_MIN_RESERVE	 0x20 /* __GFP_HIGH set. Allow access to 50%
-				       * of the min watermark.
-				       */
-#define ALLOC_CPUSET		 0x40 /* check for correct cpuset */
-#define ALLOC_CMA		 0x80 /* allow allocations from CMA areas */
-#ifdef CONFIG_ZONE_DMA32
-#define ALLOC_NOFRAGMENT	0x100 /* avoid mixing pageblock types */
-#else
-#define ALLOC_NOFRAGMENT	  0x0
-#endif
-#define ALLOC_HIGHATOMIC	0x200 /* Allows access to MIGRATE_HIGHATOMIC */
-#define ALLOC_NOLOCK		0x400 /* Only use spin_trylock in allocation path */
-#define ALLOC_KSWAPD		0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */
-
-/* Flags that allow allocations below the min watermark. */
-#define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM)
 
 enum ttu_flags;
 struct tlbflush_unmap_batch;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 617bca76db49b..58e14d1543ecb 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -26,6 +26,7 @@
 
 #include <asm/tlb.h>
 #include "internal.h"
+#include "page_alloc.h"
 #include "mm_slot.h"
 
 enum scan_result {
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index a09d85142da46..49edc37ad4324 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -66,6 +66,7 @@
 #include <trace/events/memory-failure.h>
 
 #include "swap.h"
+#include "page_alloc.h"
 #include "internal.h"
 
 static int sysctl_memory_failure_early_kill __read_mostly;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 7ac19fab22632..9539e40c478ed 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -40,6 +40,7 @@
 #include <asm/tlbflush.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 #include "shuffle.h"
 
 enum {
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 36699fabd3c22..9c740324f9160 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -119,6 +119,7 @@
 #include <linux/memory.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 
 /* Internal flags */
 #define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)	/* Skip checks for continuous vmas */
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 4026b084bd4bf..32593cca124f8 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -33,6 +33,7 @@
 #include <linux/kexec_handover.h>
 #include <linux/hugetlb.h>
 #include "internal.h"
+#include "page_alloc.h"
 #include "slab.h"
 #include "shuffle.h"
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6010693861ec2..a3ba63c7f9199 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -56,6 +56,7 @@
 #include <linux/pgalloc_tag.h>
 #include <asm/div64.h>
 #include "internal.h"
+#include "page_alloc.h"
 #include "shuffle.h"
 #include "page_reporting.h"
 
diff --git a/mm/page_alloc.h b/mm/page_alloc.h
new file mode 100644
index 0000000000000..3250d44f96457
--- /dev/null
+++ b/mm/page_alloc.h
@@ -0,0 +1,269 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * mm-internal API for the page (buddy) allocator. Public API lives in
+ * include/linux/gfp.h.
+ */
+#ifndef __MM_PAGE_ALLOC_H
+#define __MM_PAGE_ALLOC_H
+
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/nodemask.h>
+#include <linux/types.h>
+
+/* The ALLOC_WMARK bits are used as an index to zone->watermark */
+#define ALLOC_WMARK_MIN		WMARK_MIN
+#define ALLOC_WMARK_LOW		WMARK_LOW
+#define ALLOC_WMARK_HIGH	WMARK_HIGH
+#define ALLOC_NO_WATERMARKS	0x04 /* don't check watermarks at all */
+
+/* Mask to get the watermark bits */
+#define ALLOC_WMARK_MASK	(ALLOC_NO_WATERMARKS-1)
+
+/*
+ * Only MMU archs have async oom victim reclaim - aka oom_reaper so we
+ * cannot assume a reduced access to memory reserves is sufficient for
+ * !MMU
+ */
+#ifdef CONFIG_MMU
+#define ALLOC_OOM		0x08
+#else
+#define ALLOC_OOM		ALLOC_NO_WATERMARKS
+#endif
+
+#define ALLOC_NON_BLOCK		 0x10 /* Caller cannot block. Allow access
+				       * to 25% of the min watermark or
+				       * 62.5% if __GFP_HIGH is set.
+				       */
+#define ALLOC_MIN_RESERVE	 0x20 /* __GFP_HIGH set. Allow access to 50%
+				       * of the min watermark.
+				       */
+#define ALLOC_CPUSET		 0x40 /* check for correct cpuset */
+#define ALLOC_CMA		 0x80 /* allow allocations from CMA areas */
+#ifdef CONFIG_ZONE_DMA32
+#define ALLOC_NOFRAGMENT	0x100 /* avoid mixing pageblock types */
+#else
+#define ALLOC_NOFRAGMENT	  0x0
+#endif
+#define ALLOC_HIGHATOMIC	0x200 /* Allows access to MIGRATE_HIGHATOMIC */
+#define ALLOC_NOLOCK		0x400 /* Only use spin_trylock in allocation path */
+#define ALLOC_KSWAPD		0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */
+
+/* Flags that allow allocations below the min watermark. */
+#define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM)
+
+/*
+ * Structure for holding the mostly immutable allocation parameters passed
+ * between functions involved in allocations, including the alloc_pages*
+ * family of functions.
+ *
+ * nodemask, migratetype and highest_zoneidx are initialized only once in
+ * __alloc_pages() and then never change.
+ *
+ * zonelist, preferred_zone and highest_zoneidx are set first in
+ * __alloc_pages() for the fast path, and might be later changed
+ * in __alloc_pages_slowpath(). All other functions pass the whole structure
+ * by a const pointer.
+ */
+struct alloc_context {
+	struct zonelist *zonelist;
+	const nodemask_t *nodemask;
+	struct zoneref *preferred_zoneref;
+	int migratetype;
+
+	/*
+	 * highest_zoneidx represents highest usable zone index of
+	 * the allocation request. Due to the nature of the zone,
+	 * memory on lower zone than the highest_zoneidx will be
+	 * protected by lowmem_reserve[highest_zoneidx].
+	 *
+	 * highest_zoneidx is also used by reclaim/compaction to limit
+	 * the target zone since higher zone than this index cannot be
+	 * usable for this allocation request.
+	 */
+	enum zone_type highest_zoneidx;
+	bool spread_dirty_pages;
+};
+
+/*
+ * This function returns the order of a free page in the buddy system. In
+ * general, page_zone(page)->lock must be held by the caller to prevent the
+ * page from being allocated in parallel and returning garbage as the order.
+ * If a caller does not hold page_zone(page)->lock, it must guarantee that the
+ * page cannot be allocated or merged in parallel. Alternatively, it must
+ * handle invalid values gracefully, and use buddy_order_unsafe() below.
+ */
+static inline unsigned int buddy_order(struct page *page)
+{
+	/* PageBuddy() must be checked by the caller */
+	return page_private(page);
+}
+
+/*
+ * Like buddy_order(), but for callers who cannot afford to hold the zone lock.
+ * PageBuddy() should be checked first by the caller to minimize race window,
+ * and invalid values must be handled gracefully.
+ *
+ * READ_ONCE is used so that if the caller assigns the result into a local
+ * variable and e.g. tests it for valid range before using, the compiler cannot
+ * decide to remove the variable and inline the page_private(page) multiple
+ * times, potentially observing different values in the tests and the actual
+ * use of the result.
+ */
+#define buddy_order_unsafe(page)	READ_ONCE(page_private(page))
+
+/*
+ * This function checks whether a page is free && is the buddy
+ * we can coalesce a page and its buddy if
+ * (a) the buddy is not in a hole (check before calling!) &&
+ * (b) the buddy is in the buddy system &&
+ * (c) a page and its buddy have the same order &&
+ * (d) a page and its buddy are in the same zone.
+ *
+ * For recording whether a page is in the buddy system, we set PageBuddy.
+ * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
+ *
+ * For recording page's order, we use page_private(page).
+ */
+static inline bool page_is_buddy(struct page *page, struct page *buddy,
+				 unsigned int order)
+{
+	if (!page_is_guard(buddy) && !PageBuddy(buddy))
+		return false;
+
+	if (buddy_order(buddy) != order)
+		return false;
+
+	/*
+	 * zone check is done late to avoid uselessly calculating
+	 * zone/node ids for pages that could never merge.
+	 */
+	if (page_zone_id(page) != page_zone_id(buddy))
+		return false;
+
+	VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+	return true;
+}
+
+/*
+ * Locate the struct page for both the matching buddy in our
+ * pair (buddy1) and the combined O(n+1) page they form (page).
+ *
+ * 1) Any buddy B1 will have an order O twin B2 which satisfies
+ * the following equation:
+ *     B2 = B1 ^ (1 << O)
+ * For example, if the starting buddy (buddy2) is #8 its order
+ * 1 buddy is #10:
+ *     B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
+ *
+ * 2) Any buddy B will have an order O+1 parent P which
+ * satisfies the following equation:
+ *     P = B & ~(1 << O)
+ *
+ * Assumption: *_mem_map is contiguous at least up to MAX_PAGE_ORDER
+ */
+static inline unsigned long
+__find_buddy_pfn(unsigned long page_pfn, unsigned int order)
+{
+	return page_pfn ^ (1 << order);
+}
+
+/*
+ * Find the buddy of @page and validate it.
+ * @page: The input page
+ * @pfn: The pfn of the page, it saves a call to page_to_pfn() when the
+ *       function is used in the performance-critical __free_one_page().
+ * @order: The order of the page
+ * @buddy_pfn: The output pointer to the buddy pfn, it also saves a call to
+ *             page_to_pfn().
+ *
+ * The found buddy can be a non PageBuddy, out of @page's zone, or its order is
+ * not the same as @page. The validation is necessary before use it.
+ *
+ * Return: the found buddy page or NULL if not found.
+ */
+static inline struct page *find_buddy_page_pfn(struct page *page,
+			unsigned long pfn, unsigned int order, unsigned long *buddy_pfn)
+{
+	unsigned long __buddy_pfn = __find_buddy_pfn(pfn, order);
+	struct page *buddy;
+
+	buddy = page + (__buddy_pfn - pfn);
+	if (buddy_pfn)
+		*buddy_pfn = __buddy_pfn;
+
+	if (page_is_buddy(page, buddy, order))
+		return buddy;
+	return NULL;
+}
+
+extern struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
+				unsigned long end_pfn, struct zone *zone);
+
+static inline struct page *pageblock_pfn_to_page(unsigned long start_pfn,
+				unsigned long end_pfn, struct zone *zone)
+{
+	if (zone->contiguous)
+		return pfn_to_page(start_pfn);
+
+	return __pageblock_pfn_to_page(start_pfn, end_pfn, zone);
+}
+
+extern void __free_pages_core(struct page *page, unsigned int order,
+		enum meminit_context context);
+
+void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags);
+extern bool free_pages_prepare(struct page *page, unsigned int order);
+
+extern int user_min_free_kbytes;
+
+struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
+		nodemask_t *nodemask);
+#define __alloc_frozen_pages(...) \
+	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
+void free_frozen_pages(struct page *page, unsigned int order);
+void free_unref_folios(struct folio_batch *fbatch);
+
+#ifdef CONFIG_NUMA
+struct page *alloc_frozen_pages_noprof(gfp_t, unsigned int order);
+#else
+static inline struct page *alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order)
+{
+	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL);
+}
+#endif
+
+#define alloc_frozen_pages(...) \
+	alloc_hooks(alloc_frozen_pages_noprof(__VA_ARGS__))
+
+struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order);
+#define alloc_frozen_pages_nolock(...) \
+	alloc_hooks(alloc_frozen_pages_nolock_noprof(__VA_ARGS__))
+void free_frozen_pages_nolock(struct page *page, unsigned int order);
+
+extern void zone_pcp_reset(struct zone *zone);
+extern void zone_pcp_disable(struct zone *zone);
+extern void zone_pcp_enable(struct zone *zone);
+extern void zone_pcp_init(struct zone *zone);
+
+enum fallback_result {
+	/* Found suitable migratetype, *mt_out is valid. */
+	FALLBACK_FOUND,
+	/* No fallback found in requested order. */
+	FALLBACK_EMPTY,
+	/* Passed @claimable, but claiming whole block is a bad idea. */
+	FALLBACK_NOCLAIM,
+};
+enum fallback_result
+find_suitable_fallback(struct free_area *area, unsigned int order,
+		       int migratetype, bool claimable, int *mt_out);
+
+static inline bool free_area_empty(struct free_area *area, int migratetype)
+{
+	return list_empty(&area->free_list[migratetype]);
+}
+
+void page_alloc_sysctl_init(void);
+
+#endif /* __MM_PAGE_ALLOC_H */
diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c
index d2423f30577e4..a1077cef3a791 100644
--- a/mm/page_frag_cache.c
+++ b/mm/page_frag_cache.c
@@ -18,7 +18,7 @@
 #include <linux/init.h>
 #include <linux/mm.h>
 #include <linux/page_frag_cache.h>
-#include "internal.h"
+#include "page_alloc.h"
 
 static unsigned long encoded_page_create(struct page *page, unsigned int order,
 					 bool pfmemalloc)
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 32ce8a7d9df35..e5dfc7bf49446 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -11,6 +11,7 @@
 #include <linux/page_owner.h>
 #include <linux/migrate.h>
 #include "internal.h"
+#include "page_alloc.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/page_isolation.h>
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 74a844a86441e..6f580a64bdba3 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -13,7 +13,7 @@
 #include <linux/memcontrol.h>
 #include <linux/sched/clock.h>
 
-#include "internal.h"
+#include "page_alloc.h"
 
 /*
  * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
diff --git a/mm/show_mem.c b/mm/show_mem.c
index 1b721a8ade67d..d1288b4c2b640 100644
--- a/mm/show_mem.c
+++ b/mm/show_mem.c
@@ -16,6 +16,7 @@
 #include <linux/vmstat.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 #include "swap.h"
 
 atomic_long_t _totalram_pages __read_mostly;
diff --git a/mm/slub.c b/mm/slub.c
index 9ec774dc70096..877021e69cc41 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -53,6 +53,7 @@
 #include <trace/events/kmem.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 
 /*
  * Lock order:
diff --git a/mm/swap.c b/mm/swap.c
index 0132ed0fb76b6..5e389bcc073a9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -39,6 +39,7 @@
 #include <linux/buffer_head.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/pagemap.h>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 754c5f5d716aa..de1879db39160 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -66,6 +66,7 @@
 #include <linux/sched/sysctl.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 #include "swap.h"
 
 #define CREATE_TRACE_POINTS

-- 
2.54.0

Re: [PATCH v3 04/16] mm: Split out internal page_alloc.h

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> internal.h is a bit bloated, seems like time for a page_alloc.h.
> 
> Where it wasn't obvious, the heuristic for deciding what goes into this
> new header was "does it support/correspond to a definition in
> mm/page_alloc.c?"
> 
> Only need to include it from 15 .c files out of 164 so this does seem
> like a genuine reduction in scopes, which is nice. And there's no
> circular internal.h<->page_alloc.h dependency, so it seems worthwhile to
> split this up before that inevitably emerges!
> 
> Suggested-by: "David Hildenbrand (Arm)" <david@kernel.org>
> Link: https://lore.kernel.org/all/41e92bab-6882-401a-8de9-154adbdcfb36@kernel.org/
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Cool.

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

[PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Brendan Jackman]

Currently the core allocator code is controlled by ALLOC_NOLOCK, but the
main entry point function is significantly different from the normal
__alloc_frozen_pages_nolock(), this is tiring when reading the code.

Plumb the ALLOC_NOLOCK control one layer up in the call stack: create
an alloc_flags argument to __alloc_frozen_pages_nolock() (which is only
exposed to mm/) and then turn the nolock variant into a thin wrapper
that just sets that flag (as well as handling NUMA_NO_NODE, similar to
how some of the wrappers in gfp.h do).

Rationale that this doesn't change anything:

1. Simple bits: A bunch of the nolock-specific handling is just moved to
   the new alloc_order_allowed(), alloc_trylock_allowed() and
   gfp_trylock.

2. __alloc_frozen_pages_noprof() has some extra logic that wasn't
   previously in the nolock variant:

   a. Application of gfp_allowed_mask; this only affects early boot, and
      only flags that affect the slowpath get changed here.

   b. Application of current_gfp_context() - also only affects the
      slowpath

3. The slowpath itself: this is now just explicitly skipped under
   !ALLOC_TRYLOCK.

Ulterior motive: adding an alloc_flags arg to the allocator's
mm-internal entrypoint can later be used to do more allocation
customisation without needing to create new GFP flags.

While adding this flag to a bunch of places, create ALLOC_DEFAULT to
avoid a mysterious literal 0 in most places. alloc_frozen_pages_noprof()
is defined above the alloc flags so just leave that as a slightly messy
exception instead of trying to fully reorder mm/internal.h for that one
case.

No functional change intended.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 mm/hugetlb.c    |   3 +-
 mm/mempolicy.c  |  10 ++--
 mm/page_alloc.c | 178 +++++++++++++++++++++++++++++---------------------------
 mm/page_alloc.h |   6 +-
 mm/slub.c       |   6 +-
 5 files changed, 108 insertions(+), 95 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f7925624c4d2e..dfcfcfa4715bf 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1806,7 +1806,8 @@ static struct folio *alloc_buddy_frozen_folio(int order, gfp_t gfp_mask,
 	if (alloc_try_hard)
 		gfp_mask |= __GFP_RETRY_MAYFAIL;
 
-	folio = (struct folio *)__alloc_frozen_pages(gfp_mask, order, nid, nmask);
+	folio = (struct folio *)__alloc_frozen_pages(gfp_mask, order, nid, nmask,
+						     ALLOC_DEFAULT);
 
 	/*
 	 * If we did not specify __GFP_RETRY_MAYFAIL, but still got a
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 9c740324f9160..41d630f0ea821 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2426,9 +2426,11 @@ static struct page *alloc_pages_preferred_many(gfp_t gfp, unsigned int order,
 	 */
 	preferred_gfp = gfp | __GFP_NOWARN;
 	preferred_gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL);
-	page = __alloc_frozen_pages_noprof(preferred_gfp, order, nid, nodemask);
+	page = __alloc_frozen_pages_noprof(preferred_gfp, order, nid, nodemask,
+					   ALLOC_DEFAULT);
 	if (!page)
-		page = __alloc_frozen_pages_noprof(gfp, order, nid, NULL);
+		page = __alloc_frozen_pages_noprof(gfp, order, nid, NULL,
+						   ALLOC_DEFAULT);
 
 	return page;
 }
@@ -2476,7 +2478,7 @@ static struct page *alloc_pages_mpol(gfp_t gfp, unsigned int order,
 			 */
 			page = __alloc_frozen_pages_noprof(
 				gfp | __GFP_THISNODE | __GFP_NORETRY, order,
-				nid, NULL);
+				nid, NULL, ALLOC_DEFAULT);
 			if (page || !(gfp & __GFP_DIRECT_RECLAIM))
 				return page;
 			/*
@@ -2488,7 +2490,7 @@ static struct page *alloc_pages_mpol(gfp_t gfp, unsigned int order,
 		}
 	}
 
-	page = __alloc_frozen_pages_noprof(gfp, order, nid, nodemask);
+	page = __alloc_frozen_pages_noprof(gfp, order, nid, nodemask, ALLOC_DEFAULT);
 
 	if (unlikely(pol->mode == MPOL_INTERLEAVE ||
 		     pol->mode == MPOL_WEIGHTED_INTERLEAVE) && page) {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a3ba63c7f9199..8d409d075e3e9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5222,7 +5222,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
 		}
 		nr_account++;
 
-		prep_new_page(page, 0, gfp, 0);
+		prep_new_page(page, 0, gfp, ALLOC_DEFAULT);
 		set_page_refcounted(page);
 		page_array[nr_populated++] = page;
 	}
@@ -5271,24 +5271,98 @@ void free_pages_bulk(struct page **page_array, unsigned long nr_pages)
 	}
 }
 
-/*
- * This is the 'heart' of the zoned buddy allocator.
- */
-struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
-		int preferred_nid, nodemask_t *nodemask)
+static inline bool alloc_order_allowed(gfp_t gfp, unsigned int order,
+				       unsigned int alloc_flags)
 {
-	struct page *page;
-	unsigned int fastpath_alloc_flags = ALLOC_WMARK_LOW;
-	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
-	struct alloc_context ac = { };
+	if (alloc_flags & ALLOC_NOLOCK)
+		return pcp_allowed_order(order);
 
 	/*
 	 * There are several places where we assume that the order value is sane
 	 * so bail out early if the request is out of bound.
 	 */
-	if (WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp))
+	return !(WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp));
+}
+
+static inline bool alloc_trylock_allowed(void)
+{
+	/*
+	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
+	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
+	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
+	 * mark the task as the owner of another rt_spin_lock which will
+	 * confuse PI logic, so return immediately if called from hard IRQ or
+	 * NMI.
+	 *
+	 * Note, irqs_disabled() case is ok. This function can be called
+	 * from raw_spin_lock_irqsave region.
+	 */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
+		return false;
+
+	/* On UP, spin_trylock() always succeeds even when it is locked */
+	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
+		return false;
+
+	/* Bailout, since _deferred_grow_zone() needs to take a lock */
+	if (deferred_pages_enabled())
+		return false;
+
+	return true;
+}
+
+/*
+ * GFP flags to set for ALLOC_NOLOCK i.e. alloc_pages_nolock().
+ *
+ * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed.
+ * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd
+ * is not safe in arbitrary context.
+ *
+ * These two are the conditions for gfpflags_allow_spinning() being true.
+ *
+ * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason
+ * to warn. Also warn would trigger printk() which is unsafe from
+ * various contexts. We cannot use printk_deferred_enter() to mitigate,
+ * since the running context is unknown.
+ *
+ * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below
+ * is safe in any context. Also zeroing the page is mandatory for
+ * BPF use cases.
+ *
+ * Though __GFP_NOMEMALLOC is not checked in the code path below,
+ * specify it here to highlight that alloc_pages_nolock()
+ * doesn't want to deplete reserves.
+ */
+static const gfp_t gfp_nolock = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC |
+				__GFP_COMP;
+
+/*
+ * This is the 'heart' of the zoned buddy allocator.
+ */
+struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
+		int preferred_nid, nodemask_t *nodemask, unsigned int alloc_flags)
+{
+	struct page *page;
+	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
+	struct alloc_context ac = { };
+	unsigned int fastpath_alloc_flags = alloc_flags;
+
+	/* Other flags could be supported later if needed. */
+	if (WARN_ON(alloc_flags & ~ALLOC_NOLOCK))
 		return NULL;
 
+	if (!alloc_order_allowed(gfp, order, alloc_flags))
+		return NULL;
+
+	if (alloc_flags & ALLOC_NOLOCK) {
+		VM_WARN_ON_ONCE(gfp & ~__GFP_ACCOUNT);
+		if (!alloc_trylock_allowed())
+			return NULL;
+		gfp |= gfp_nolock;
+	} else {
+		fastpath_alloc_flags |= ALLOC_WMARK_LOW;
+	}
+
 	gfp &= gfp_allowed_mask;
 	/*
 	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
@@ -5310,9 +5384,9 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 	fastpath_alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
 	fastpath_alloc_flags |= alloc_flags_nonblocking(gfp, order) & ALLOC_HIGHATOMIC;
 
-	/* First allocation attempt */
+	/* First allocation attempt (or, for nolock, only attempt) */
 	page = get_page_from_freelist(alloc_gfp, order, fastpath_alloc_flags, &ac);
-	if (likely(page))
+	if (likely(page) || (alloc_flags & ALLOC_NOLOCK))
 		goto out;
 
 	alloc_gfp = gfp;
@@ -5329,7 +5403,8 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 out:
 	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
 	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
-		free_frozen_pages(page, order);
+		__free_frozen_pages(page, order,
+				    alloc_flags & ALLOC_NOLOCK ? FPI_TRYLOCK : 0);
 		page = NULL;
 	}
 
@@ -5345,7 +5420,8 @@ struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
 {
 	struct page *page;
 
-	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask);
+	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask,
+					   ALLOC_DEFAULT);
 	if (page)
 		set_page_refcounted(page);
 	return page;
@@ -7875,80 +7951,10 @@ static bool __free_unaccepted(struct page *page)
 
 struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order)
 {
-	/*
-	 * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed.
-	 * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd
-	 * is not safe in arbitrary context.
-	 *
-	 * These two are the conditions for gfpflags_allow_spinning() being true.
-	 *
-	 * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason
-	 * to warn. Also warn would trigger printk() which is unsafe from
-	 * various contexts. We cannot use printk_deferred_enter() to mitigate,
-	 * since the running context is unknown.
-	 *
-	 * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below
-	 * is safe in any context. Also zeroing the page is mandatory for
-	 * BPF use cases.
-	 *
-	 * Though __GFP_NOMEMALLOC is not checked in the code path below,
-	 * specify it here to highlight that alloc_pages_nolock()
-	 * doesn't want to deplete reserves.
-	 */
-	gfp_t alloc_gfp = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC | __GFP_COMP
-			| gfp_flags;
-	unsigned int alloc_flags = ALLOC_NOLOCK;
-	struct alloc_context ac = { };
-	struct page *page;
-
-	VM_WARN_ON_ONCE(gfp_flags & ~__GFP_ACCOUNT);
-	/*
-	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
-	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
-	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
-	 * mark the task as the owner of another rt_spin_lock which will
-	 * confuse PI logic, so return immediately if called from hard IRQ or
-	 * NMI.
-	 *
-	 * Note, irqs_disabled() case is ok. This function can be called
-	 * from raw_spin_lock_irqsave region.
-	 */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
-		return NULL;
-
-	/* On UP, spin_trylock() always succeeds even when it is locked */
-	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
-		return NULL;
-
-	if (!pcp_allowed_order(order))
-		return NULL;
-
-	/* Bailout, since _deferred_grow_zone() needs to take a lock */
-	if (deferred_pages_enabled())
-		return NULL;
-
 	if (nid == NUMA_NO_NODE)
 		nid = numa_node_id();
 
-	prepare_alloc_pages(alloc_gfp, order, nid, NULL, &ac,
-			    &alloc_gfp, &alloc_flags);
-
-	/*
-	 * Best effort allocation from percpu free list.
-	 * If it's empty attempt to spin_trylock zone->lock.
-	 */
-	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
-
-	/* Unlike regular alloc_pages() there is no __alloc_pages_slowpath(). */
-
-	if (memcg_kmem_online() && page && (gfp_flags & __GFP_ACCOUNT) &&
-	    unlikely(__memcg_kmem_charge_page(page, alloc_gfp, order) != 0)) {
-		__free_frozen_pages(page, order, FPI_TRYLOCK);
-		page = NULL;
-	}
-	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
-	kmsan_alloc_page(page, order, alloc_gfp);
-	return page;
+	return __alloc_frozen_pages_noprof(gfp_flags, order, nid, NULL, ALLOC_NOLOCK);
 }
 /**
  * alloc_pages_nolock - opportunistic reentrant allocation from any context
diff --git a/mm/page_alloc.h b/mm/page_alloc.h
index 3250d44f96457..e16f905f859a7 100644
--- a/mm/page_alloc.h
+++ b/mm/page_alloc.h
@@ -11,6 +11,7 @@
 #include <linux/nodemask.h>
 #include <linux/types.h>
 
+#define ALLOC_DEFAULT		0
 /* The ALLOC_WMARK bits are used as an index to zone->watermark */
 #define ALLOC_WMARK_MIN		WMARK_MIN
 #define ALLOC_WMARK_LOW		WMARK_LOW
@@ -219,7 +220,7 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
 extern int user_min_free_kbytes;
 
 struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
-		nodemask_t *nodemask);
+		nodemask_t *nodemask, unsigned int alloc_flags);
 #define __alloc_frozen_pages(...) \
 	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
 void free_frozen_pages(struct page *page, unsigned int order);
@@ -230,7 +231,8 @@ struct page *alloc_frozen_pages_noprof(gfp_t, unsigned int order);
 #else
 static inline struct page *alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order)
 {
-	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL);
+	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL,
+					   0 /* ALLOC_DEFAULT */);
 }
 #endif
 
diff --git a/mm/slub.c b/mm/slub.c
index 877021e69cc41..3989b4758ae0a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3292,7 +3292,8 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node,
 	else if (node == NUMA_NO_NODE)
 		page = alloc_frozen_pages(flags, order);
 	else
-		page = __alloc_frozen_pages(flags, order, node, NULL);
+		page = __alloc_frozen_pages(flags, order, node, NULL,
+					    ALLOC_DEFAULT);
 
 	if (!page)
 		return NULL;
@@ -5302,7 +5303,8 @@ static void *___kmalloc_large_node(size_t size, gfp_t flags, int node)
 	if (node == NUMA_NO_NODE)
 		page = alloc_frozen_pages_noprof(flags, order);
 	else
-		page = __alloc_frozen_pages_noprof(flags, order, node, NULL);
+		page = __alloc_frozen_pages_noprof(flags, order, node, NULL,
+						   ALLOC_DEFAULT);
 
 	if (page) {
 		ptr = page_address(page);

-- 
2.54.0

Re: [PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Harry Yoo]

[-- Attachment #1.1: Type: text/plain, Size: 4198 bytes --]



On 6/29/26 10:11 PM, Brendan Jackman wrote:
> Currently the core allocator code is controlled by ALLOC_NOLOCK, but the
> main entry point function is significantly different from the normal
> __alloc_frozen_pages_nolock(), this is tiring when reading the code.
> 
> Plumb the ALLOC_NOLOCK control one layer up in the call stack: create
> an alloc_flags argument to __alloc_frozen_pages_nolock() (which is only
> exposed to mm/) and then turn the nolock variant into a thin wrapper
> that just sets that flag (as well as handling NUMA_NO_NODE, similar to
> how some of the wrappers in gfp.h do).
> 
> Rationale that this doesn't change anything:
>
> 1. Simple bits: A bunch of the nolock-specific handling is just moved to
>    the new alloc_order_allowed(), alloc_trylock_allowed() and
>    gfp_trylock.

Right.

> 2. __alloc_frozen_pages_noprof() has some extra logic that wasn't
>    previously in the nolock variant:
> 
>    a. Application of gfp_allowed_mask; this only affects early boot, and
>       only flags that affect the slowpath get changed here.

gfp_allowed_mask clears __GFP_RECLAIM, and that means now allocations
with GFP_KERNEL during early boot would see
gfpflags_allow_spinning() = false.

The helper is not used in in the page allocator, but used in
memcg/stackdepot/page_owner.

>    b. Application of current_gfp_context() - also only affects the
>       slowpath

PF_MEMALLOC_PIN affects the fast path, but ALLOC_NOLOCK users
won't be affected.

What about alloc_flags_nofragment/nonblocking()?

> 3. The slowpath itself: this is now just explicitly skipped under
>    !ALLOC_TRYLOCK.

Right.

> Ulterior motive: adding an alloc_flags arg to the allocator's
> mm-internal entrypoint can later be used to do more allocation
> customisation without needing to create new GFP flags.
> 
> While adding this flag to a bunch of places, create ALLOC_DEFAULT to
> avoid a mysterious literal 0 in most places.
>
> alloc_frozen_pages_noprof() is defined above the alloc flags

The function is defined below the alloc flags, no?

> so just leave that as a slightly messy
> exception instead of trying to fully reorder mm/internal.h for that one
> case.
> 
> No functional change intended.
> 
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
>  mm/hugetlb.c    |   3 +-
>  mm/mempolicy.c  |  10 ++--
>  mm/page_alloc.c | 178 +++++++++++++++++++++++++++++---------------------------
>  mm/page_alloc.h |   6 +-
>  mm/slub.c       |   6 +-
>  5 files changed, 108 insertions(+), 95 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a3ba63c7f9199..8d409d075e3e9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5271,24 +5271,98 @@ void free_pages_bulk(struct page **page_array, unsigned long nr_pages)
>  	}
>  }
>  
> +static inline bool alloc_trylock_allowed(void)
> +{
> +	/*
> +	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
> +	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
> +	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
> +	 * mark the task as the owner of another rt_spin_lock which will
> +	 * confuse PI logic, so return immediately if called from hard IRQ or
> +	 * NMI.
> +	 *
> +	 * Note, irqs_disabled() case is ok. This function can be called
> +	 * from raw_spin_lock_irqsave region.
> +	 */
> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
> +		return false;
> +
> +	/* On UP, spin_trylock() always succeeds even when it is locked */
> +	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
> +		return false;

Except for deferred_pages_enabled(), it's not specific to the page
allocator. SLUB has

	/*
	 * See the comment for the same check in
	 * alloc_frozen_pages_nolock_noprof()
	 */

... and repeats the same thing as above.

Perhaps let's factor it out into a helper
rather than trying not to forget to update the other place?

> +	/* Bailout, since _deferred_grow_zone() needs to take a lock */
> +	if (deferred_pages_enabled())
> +		return false;
> +
> +	return true;
> +}


-- 
Cheers,
Harry / Hyeonggon

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Re: [PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Vlastimil Babka (SUSE)]

On 6/30/26 15:36, Harry Yoo wrote:
> 
> 
> On 6/29/26 10:11 PM, Brendan Jackman wrote:
>> Currently the core allocator code is controlled by ALLOC_NOLOCK, but the
>> main entry point function is significantly different from the normal
>> __alloc_frozen_pages_nolock(), this is tiring when reading the code.
>> 
>> Plumb the ALLOC_NOLOCK control one layer up in the call stack: create
>> an alloc_flags argument to __alloc_frozen_pages_nolock() (which is only
>> exposed to mm/) and then turn the nolock variant into a thin wrapper
>> that just sets that flag (as well as handling NUMA_NO_NODE, similar to
>> how some of the wrappers in gfp.h do).
>> 
>> Rationale that this doesn't change anything:
>>
>> 1. Simple bits: A bunch of the nolock-specific handling is just moved to
>>    the new alloc_order_allowed(), alloc_trylock_allowed() and
>>    gfp_trylock.
> 
> Right.
> 
>> 2. __alloc_frozen_pages_noprof() has some extra logic that wasn't
>>    previously in the nolock variant:
>> 
>>    a. Application of gfp_allowed_mask; this only affects early boot, and
>>       only flags that affect the slowpath get changed here.
> 
> gfp_allowed_mask clears __GFP_RECLAIM, and that means now allocations
> with GFP_KERNEL during early boot would see
> gfpflags_allow_spinning() = false.

Is it a problem though? non-nolock allocations were affected before (the
masking existed for those already) and will be affected now the same, and
_nolock() allocations don't pass __GFP_RECLAIM in the first place, so the
masking can't affect them?

> The helper is not used in in the page allocator, but used in
> memcg/stackdepot/page_owner.
> 
>>    b. Application of current_gfp_context() - also only affects the
>>       slowpath
> 
> PF_MEMALLOC_PIN affects the fast path, but ALLOC_NOLOCK users
> won't be affected.

And it wouldn't be wrong if they were? It only clears __GFP_MOVABLE?

> What about alloc_flags_nofragment/nonblocking()?

ALLOC_NOFRAGMENT due to e.g. defrag_mode could be a problem indeed, if
there's no slowpath. Make ALLOC_NOLOCK override it?

nonblocking() is probably fine?

> 

Re: [PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Brendan Jackman]

On Tue Jun 30, 2026 at 3:34 PM UTC, Vlastimil Babka (SUSE) wrote:
> On 6/30/26 15:36, Harry Yoo wrote:
>> 
>> 
>> On 6/29/26 10:11 PM, Brendan Jackman wrote:
>>> Currently the core allocator code is controlled by ALLOC_NOLOCK, but the
>>> main entry point function is significantly different from the normal
>>> __alloc_frozen_pages_nolock(), this is tiring when reading the code.
>>> 
>>> Plumb the ALLOC_NOLOCK control one layer up in the call stack: create
>>> an alloc_flags argument to __alloc_frozen_pages_nolock() (which is only
>>> exposed to mm/) and then turn the nolock variant into a thin wrapper
>>> that just sets that flag (as well as handling NUMA_NO_NODE, similar to
>>> how some of the wrappers in gfp.h do).
>>> 
>>> Rationale that this doesn't change anything:
>>>
>>> 1. Simple bits: A bunch of the nolock-specific handling is just moved to
>>>    the new alloc_order_allowed(), alloc_trylock_allowed() and
>>>    gfp_trylock.
>> 
>> Right.
>> 
>>> 2. __alloc_frozen_pages_noprof() has some extra logic that wasn't
>>>    previously in the nolock variant:
>>> 
>>>    a. Application of gfp_allowed_mask; this only affects early boot, and
>>>       only flags that affect the slowpath get changed here.
>> 
>> gfp_allowed_mask clears __GFP_RECLAIM, and that means now allocations
>> with GFP_KERNEL during early boot would see
>> gfpflags_allow_spinning() = false.
>
> Is it a problem though? non-nolock allocations were affected before (the
> masking existed for those already) and will be affected now the same, and
> _nolock() allocations don't pass __GFP_RECLAIM in the first place, so the
> masking can't affect them?

This was my thinking too.

>> The helper is not used in in the page allocator, but used in
>> memcg/stackdepot/page_owner.
>> 
>>>    b. Application of current_gfp_context() - also only affects the
>>>       slowpath
>> 
>> PF_MEMALLOC_PIN affects the fast path, but ALLOC_NOLOCK users
>> won't be affected.
>
> And it wouldn't be wrong if they were? It only clears __GFP_MOVABLE?
>
>> What about alloc_flags_nofragment/nonblocking()?
>
> ALLOC_NOFRAGMENT due to e.g. defrag_mode could be a problem indeed, if
> there's no slowpath. Make ALLOC_NOLOCK override it?

Yeah calling alloc_flags_nofragment() here is a bug in the patch,
and Sashiko also complained: 

https://lore.kernel.org/all/20260629142921.9A05A1F000E9@smtp.kernel.org/

Like I said in the reply to that thread I think maybe we _do_ want to
set ALLOC_NOFRAGMENT for nolock allocations? But, that is a functional
change, it doesn't belong in this series.

> nonblocking() is probably fine?

Yeah, I believe this is fine.

Re: [PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Brendan Jackman]

On Tue Jun 30, 2026 at 1:36 PM UTC, Harry Yoo wrote:
>> Ulterior motive: adding an alloc_flags arg to the allocator's
>> mm-internal entrypoint can later be used to do more allocation
>> customisation without needing to create new GFP flags.
>> 
>> While adding this flag to a bunch of places, create ALLOC_DEFAULT to
>> avoid a mysterious literal 0 in most places.
>>
>> alloc_frozen_pages_noprof() is defined above the alloc flags
>
> The function is defined below the alloc flags, no?

Yep this paragraph is stale since I created mm/page_alloc.h, will remove
it.

>> so just leave that as a slightly messy
>> exception instead of trying to fully reorder mm/internal.h for that one
>> case.
>> 
>> No functional change intended.
>> 
>> Signed-off-by: Brendan Jackman <jackmanb@google.com>
>> ---
>>  mm/hugetlb.c    |   3 +-
>>  mm/mempolicy.c  |  10 ++--
>>  mm/page_alloc.c | 178 +++++++++++++++++++++++++++++---------------------------
>>  mm/page_alloc.h |   6 +-
>>  mm/slub.c       |   6 +-
>>  5 files changed, 108 insertions(+), 95 deletions(-)
>> 
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index a3ba63c7f9199..8d409d075e3e9 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -5271,24 +5271,98 @@ void free_pages_bulk(struct page **page_array, unsigned long nr_pages)
>>  	}
>>  }
>>  
>> +static inline bool alloc_trylock_allowed(void)
>> +{
>> +	/*
>> +	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
>> +	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
>> +	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
>> +	 * mark the task as the owner of another rt_spin_lock which will
>> +	 * confuse PI logic, so return immediately if called from hard IRQ or
>> +	 * NMI.
>> +	 *
>> +	 * Note, irqs_disabled() case is ok. This function can be called
>> +	 * from raw_spin_lock_irqsave region.
>> +	 */
>> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
>> +		return false;
>> +
>> +	/* On UP, spin_trylock() always succeeds even when it is locked */
>> +	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
>> +		return false;
>
> Except for deferred_pages_enabled(), it's not specific to the page
> allocator. SLUB has
>
> 	/*
> 	 * See the comment for the same check in
> 	 * alloc_frozen_pages_nolock_noprof()
> 	 */
>
> ... and repeats the same thing as above.
>
> Perhaps let's factor it out into a helper
> rather than trying not to forget to update the other place?

Hm, not sure about this. I think I would say it's a "coincidence" that
these two bits of code look the same? Like, page_alloc.c uses
spin_trylock() so you can't do alloc_pages_nolock() from IRQ on
PREEMPT_RT. slub.c ALSO uses spin_trylock(), so you ALSO can't use
kmalloc_nolock() in those scenarios. But those are two different facts
that just happen to be isomorphic? Putting them into a shared helper
would kinda imply that these are part of a single system with inherently
coupled constraints.

I dunno I'm being a bit of a ponderous philosopher there, I don't have
particularly strong feelings. But I'd lean towards leaving this out of
the patchset since the potential deduplication isn't really related to
the other cleanups anyway.

Re: [PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> Currently the core allocator code is controlled by ALLOC_NOLOCK, but the
> main entry point function is significantly different from the normal

Let's mention it explicitly, alloc_frozen_pages_nolock_noprof().

> __alloc_frozen_pages_nolock(), this is tiring when reading the code.

You mean __alloc_frozen_pages_noprof()?

> 
> Plumb the ALLOC_NOLOCK control one layer up in the call stack: create
> an alloc_flags argument to __alloc_frozen_pages_nolock() (which is only

Again __alloc_frozen_pages_noprof()

> exposed to mm/) and then turn the nolock variant into a thin wrapper
> that just sets that flag (as well as handling NUMA_NO_NODE, similar to
> how some of the wrappers in gfp.h do).
> 
> Rationale that this doesn't change anything:
> 
> 1. Simple bits: A bunch of the nolock-specific handling is just moved to
>    the new alloc_order_allowed(), alloc_trylock_allowed() and
>    gfp_trylock.

Should be alloc_nolock_allowed() and gfp_nolock

> 2. __alloc_frozen_pages_noprof() has some extra logic that wasn't
>    previously in the nolock variant:
> 
>    a. Application of gfp_allowed_mask; this only affects early boot, and
>       only flags that affect the slowpath get changed here.

As discussed in reply to Harry, I'd mention the flags excluded by
GFP_BOOT_MASK are not usable by _nolock() anyway.

>    b. Application of current_gfp_context() - also only affects the
>       slowpath
> 
> 3. The slowpath itself: this is now just explicitly skipped under
>    !ALLOC_TRYLOCK.

ALLOC_NOLOCK.

> 
> Ulterior motive: adding an alloc_flags arg to the allocator's
> mm-internal entrypoint can later be used to do more allocation
> customisation without needing to create new GFP flags.
> 
> While adding this flag to a bunch of places, create ALLOC_DEFAULT to
> avoid a mysterious literal 0 in most places.


> alloc_frozen_pages_noprof()
> is defined above the alloc flags so just leave that as a slightly messy
> exception instead of trying to fully reorder mm/internal.h for that one
> case.

This no longer applies in v3?

> No functional change intended.
> 
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
>  mm/hugetlb.c    |   3 +-
>  mm/mempolicy.c  |  10 ++--
>  mm/page_alloc.c | 178 +++++++++++++++++++++++++++++---------------------------
>  mm/page_alloc.h |   6 +-
>  mm/slub.c       |   6 +-
>  5 files changed, 108 insertions(+), 95 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index f7925624c4d2e..dfcfcfa4715bf 100644

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a3ba63c7f9199..8d409d075e3e9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5222,7 +5222,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
>  		}
>  		nr_account++;
>  
> -		prep_new_page(page, 0, gfp, 0);
> +		prep_new_page(page, 0, gfp, ALLOC_DEFAULT);
>  		set_page_refcounted(page);
>  		page_array[nr_populated++] = page;
>  	}
> @@ -5271,24 +5271,98 @@ void free_pages_bulk(struct page **page_array, unsigned long nr_pages)
>  	}
>  }
>  
> -/*
> - * This is the 'heart' of the zoned buddy allocator.
> - */
> -struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
> -		int preferred_nid, nodemask_t *nodemask)
> +static inline bool alloc_order_allowed(gfp_t gfp, unsigned int order,
> +				       unsigned int alloc_flags)
>  {
> -	struct page *page;
> -	unsigned int fastpath_alloc_flags = ALLOC_WMARK_LOW;
> -	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
> -	struct alloc_context ac = { };
> +	if (alloc_flags & ALLOC_NOLOCK)
> +		return pcp_allowed_order(order);
>  
>  	/*
>  	 * There are several places where we assume that the order value is sane
>  	 * so bail out early if the request is out of bound.
>  	 */
> -	if (WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp))
> +	return !(WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp));
> +}
> +
> +static inline bool alloc_trylock_allowed(void)

alloc_nolock_allowed()

> +{
> +	/*
> +	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
> +	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
> +	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
> +	 * mark the task as the owner of another rt_spin_lock which will
> +	 * confuse PI logic, so return immediately if called from hard IRQ or
> +	 * NMI.
> +	 *
> +	 * Note, irqs_disabled() case is ok. This function can be called
> +	 * from raw_spin_lock_irqsave region.
> +	 */
> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
> +		return false;
> +
> +	/* On UP, spin_trylock() always succeeds even when it is locked */
> +	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
> +		return false;
> +
> +	/* Bailout, since _deferred_grow_zone() needs to take a lock */
> +	if (deferred_pages_enabled())
> +		return false;
> +
> +	return true;
> +}
> +
> +/*
> + * GFP flags to set for ALLOC_NOLOCK i.e. alloc_pages_nolock().
> + *
> + * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed.
> + * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd
> + * is not safe in arbitrary context.
> + *
> + * These two are the conditions for gfpflags_allow_spinning() being true.
> + *
> + * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason
> + * to warn. Also warn would trigger printk() which is unsafe from
> + * various contexts. We cannot use printk_deferred_enter() to mitigate,
> + * since the running context is unknown.
> + *
> + * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below
> + * is safe in any context. Also zeroing the page is mandatory for
> + * BPF use cases.
> + *
> + * Though __GFP_NOMEMALLOC is not checked in the code path below,
> + * specify it here to highlight that alloc_pages_nolock()
> + * doesn't want to deplete reserves.
> + */
> +static const gfp_t gfp_nolock = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC |
> +				__GFP_COMP;
> +
> +/*
> + * This is the 'heart' of the zoned buddy allocator.
> + */
> +struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
> +		int preferred_nid, nodemask_t *nodemask, unsigned int alloc_flags)
> +{
> +	struct page *page;
> +	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
> +	struct alloc_context ac = { };
> +	unsigned int fastpath_alloc_flags = alloc_flags;
> +
> +	/* Other flags could be supported later if needed. */
> +	if (WARN_ON(alloc_flags & ~ALLOC_NOLOCK))
>  		return NULL;
>  
> +	if (!alloc_order_allowed(gfp, order, alloc_flags))
> +		return NULL;
> +
> +	if (alloc_flags & ALLOC_NOLOCK) {
> +		VM_WARN_ON_ONCE(gfp & ~__GFP_ACCOUNT);
> +		if (!alloc_trylock_allowed())
> +			return NULL;
> +		gfp |= gfp_nolock;

I think we could do a
		fastpath_alloc_flags |= ALLOC_WMARK_MIN;

to make it explicit, even though it's a no-op (the value is 0) and
alloc_frozen_pages_nolock_noprof() didn't do it.

> +	} else {
> +		fastpath_alloc_flags |= ALLOC_WMARK_LOW;
> +	}
> +
>  	gfp &= gfp_allowed_mask;
>  	/*
>  	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
> @@ -5310,9 +5384,9 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>  	fastpath_alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
>  	fastpath_alloc_flags |= alloc_flags_nonblocking(gfp, order) & ALLOC_HIGHATOMIC;
>  
> -	/* First allocation attempt */
> +	/* First allocation attempt (or, for nolock, only attempt) */
>  	page = get_page_from_freelist(alloc_gfp, order, fastpath_alloc_flags, &ac);
> -	if (likely(page))
> +	if (likely(page) || (alloc_flags & ALLOC_NOLOCK))
>  		goto out;
>  
>  	alloc_gfp = gfp;
> @@ -5329,7 +5403,8 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>  out:
>  	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
>  	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
> -		free_frozen_pages(page, order);
> +		__free_frozen_pages(page, order,
> +				    alloc_flags & ALLOC_NOLOCK ? FPI_TRYLOCK : 0);
>  		page = NULL;
>  	}
>  
> @@ -5345,7 +5420,8 @@ struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
>  {
>  	struct page *page;
>  
> -	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask);
> +	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask,
> +					   ALLOC_DEFAULT);
>  	if (page)
>  		set_page_refcounted(page);
>  	return page;
> @@ -7875,80 +7951,10 @@ static bool __free_unaccepted(struct page *page)
>  
>  struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order)
>  {
> -	/*
> -	 * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed.
> -	 * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd
> -	 * is not safe in arbitrary context.
> -	 *
> -	 * These two are the conditions for gfpflags_allow_spinning() being true.
> -	 *
> -	 * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason
> -	 * to warn. Also warn would trigger printk() which is unsafe from
> -	 * various contexts. We cannot use printk_deferred_enter() to mitigate,
> -	 * since the running context is unknown.
> -	 *
> -	 * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below
> -	 * is safe in any context. Also zeroing the page is mandatory for
> -	 * BPF use cases.
> -	 *
> -	 * Though __GFP_NOMEMALLOC is not checked in the code path below,
> -	 * specify it here to highlight that alloc_pages_nolock()
> -	 * doesn't want to deplete reserves.
> -	 */
> -	gfp_t alloc_gfp = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC | __GFP_COMP
> -			| gfp_flags;
> -	unsigned int alloc_flags = ALLOC_NOLOCK;
> -	struct alloc_context ac = { };
> -	struct page *page;
> -
> -	VM_WARN_ON_ONCE(gfp_flags & ~__GFP_ACCOUNT);
> -	/*
> -	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
> -	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
> -	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
> -	 * mark the task as the owner of another rt_spin_lock which will
> -	 * confuse PI logic, so return immediately if called from hard IRQ or
> -	 * NMI.
> -	 *
> -	 * Note, irqs_disabled() case is ok. This function can be called
> -	 * from raw_spin_lock_irqsave region.
> -	 */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
> -		return NULL;
> -
> -	/* On UP, spin_trylock() always succeeds even when it is locked */
> -	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
> -		return NULL;
> -
> -	if (!pcp_allowed_order(order))
> -		return NULL;
> -
> -	/* Bailout, since _deferred_grow_zone() needs to take a lock */
> -	if (deferred_pages_enabled())
> -		return NULL;
> -
>  	if (nid == NUMA_NO_NODE)
>  		nid = numa_node_id();
>  
> -	prepare_alloc_pages(alloc_gfp, order, nid, NULL, &ac,
> -			    &alloc_gfp, &alloc_flags);
> -
> -	/*
> -	 * Best effort allocation from percpu free list.
> -	 * If it's empty attempt to spin_trylock zone->lock.
> -	 */
> -	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
> -
> -	/* Unlike regular alloc_pages() there is no __alloc_pages_slowpath(). */
> -
> -	if (memcg_kmem_online() && page && (gfp_flags & __GFP_ACCOUNT) &&
> -	    unlikely(__memcg_kmem_charge_page(page, alloc_gfp, order) != 0)) {
> -		__free_frozen_pages(page, order, FPI_TRYLOCK);
> -		page = NULL;
> -	}
> -	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
> -	kmsan_alloc_page(page, order, alloc_gfp);
> -	return page;
> +	return __alloc_frozen_pages_noprof(gfp_flags, order, nid, NULL, ALLOC_NOLOCK);
>  }
>  /**
>   * alloc_pages_nolock - opportunistic reentrant allocation from any context
> diff --git a/mm/page_alloc.h b/mm/page_alloc.h
> index 3250d44f96457..e16f905f859a7 100644
> --- a/mm/page_alloc.h
> +++ b/mm/page_alloc.h
> @@ -11,6 +11,7 @@
>  #include <linux/nodemask.h>
>  #include <linux/types.h>
>  
> +#define ALLOC_DEFAULT		0
>  /* The ALLOC_WMARK bits are used as an index to zone->watermark */
>  #define ALLOC_WMARK_MIN		WMARK_MIN
>  #define ALLOC_WMARK_LOW		WMARK_LOW
> @@ -219,7 +220,7 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
>  extern int user_min_free_kbytes;
>  
>  struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
> -		nodemask_t *nodemask);
> +		nodemask_t *nodemask, unsigned int alloc_flags);
>  #define __alloc_frozen_pages(...) \
>  	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
>  void free_frozen_pages(struct page *page, unsigned int order);
> @@ -230,7 +231,8 @@ struct page *alloc_frozen_pages_noprof(gfp_t, unsigned int order);
>  #else
>  static inline struct page *alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order)
>  {
> -	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL);
> +	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL,
> +					   0 /* ALLOC_DEFAULT */);

Can use ALLOC_DEFAULT now.

>  }
>  #endif
>  

Re: [PATCH v3 05/16] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()

[Brendan Jackman]

On Tue Jun 30, 2026 at 4:16 PM UTC, Vlastimil Babka (SUSE) wrote:
> On 6/29/26 15:11, Brendan Jackman wrote:
>> Currently the core allocator code is controlled by ALLOC_NOLOCK, but the
>> main entry point function is significantly different from the normal
>
> Let's mention it explicitly, alloc_frozen_pages_nolock_noprof().
>
>> __alloc_frozen_pages_nolock(), this is tiring when reading the code.
>
> You mean __alloc_frozen_pages_noprof()?
>
>> 
>> Plumb the ALLOC_NOLOCK control one layer up in the call stack: create
>> an alloc_flags argument to __alloc_frozen_pages_nolock() (which is only
>
> Again __alloc_frozen_pages_noprof()
>
>> exposed to mm/) and then turn the nolock variant into a thin wrapper
>> that just sets that flag (as well as handling NUMA_NO_NODE, similar to
>> how some of the wrappers in gfp.h do).
>> 
>> Rationale that this doesn't change anything:
>> 
>> 1. Simple bits: A bunch of the nolock-specific handling is just moved to
>>    the new alloc_order_allowed(), alloc_trylock_allowed() and
>>    gfp_trylock.
>
> Should be alloc_nolock_allowed() and gfp_nolock
>
>> 2. __alloc_frozen_pages_noprof() has some extra logic that wasn't
>>    previously in the nolock variant:
>> 
>>    a. Application of gfp_allowed_mask; this only affects early boot, and
>>       only flags that affect the slowpath get changed here.
>
> As discussed in reply to Harry, I'd mention the flags excluded by
> GFP_BOOT_MASK are not usable by _nolock() anyway.
>
>>    b. Application of current_gfp_context() - also only affects the
>>       slowpath
>> 
>> 3. The slowpath itself: this is now just explicitly skipped under
>>    !ALLOC_TRYLOCK.
>
> ALLOC_NOLOCK.
>
>> 
>> Ulterior motive: adding an alloc_flags arg to the allocator's
>> mm-internal entrypoint can later be used to do more allocation
>> customisation without needing to create new GFP flags.
>> 
>> While adding this flag to a bunch of places, create ALLOC_DEFAULT to
>> avoid a mysterious literal 0 in most places.
>
>
>> alloc_frozen_pages_noprof()
>> is defined above the alloc flags so just leave that as a slightly messy
>> exception instead of trying to fully reorder mm/internal.h for that one
>> case.
>
> This no longer applies in v3?
>
>> No functional change intended.
>> 
>> Signed-off-by: Brendan Jackman <jackmanb@google.com>
>> ---
>>  mm/hugetlb.c    |   3 +-
>>  mm/mempolicy.c  |  10 ++--
>>  mm/page_alloc.c | 178 +++++++++++++++++++++++++++++---------------------------
>>  mm/page_alloc.h |   6 +-
>>  mm/slub.c       |   6 +-
>>  5 files changed, 108 insertions(+), 95 deletions(-)
>> 
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index f7925624c4d2e..dfcfcfa4715bf 100644
>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index a3ba63c7f9199..8d409d075e3e9 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -5222,7 +5222,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
>>  		}
>>  		nr_account++;
>>  
>> -		prep_new_page(page, 0, gfp, 0);
>> +		prep_new_page(page, 0, gfp, ALLOC_DEFAULT);
>>  		set_page_refcounted(page);
>>  		page_array[nr_populated++] = page;
>>  	}
>> @@ -5271,24 +5271,98 @@ void free_pages_bulk(struct page **page_array, unsigned long nr_pages)
>>  	}
>>  }
>>  
>> -/*
>> - * This is the 'heart' of the zoned buddy allocator.
>> - */
>> -struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>> -		int preferred_nid, nodemask_t *nodemask)
>> +static inline bool alloc_order_allowed(gfp_t gfp, unsigned int order,
>> +				       unsigned int alloc_flags)
>>  {
>> -	struct page *page;
>> -	unsigned int fastpath_alloc_flags = ALLOC_WMARK_LOW;
>> -	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
>> -	struct alloc_context ac = { };
>> +	if (alloc_flags & ALLOC_NOLOCK)
>> +		return pcp_allowed_order(order);
>>  
>>  	/*
>>  	 * There are several places where we assume that the order value is sane
>>  	 * so bail out early if the request is out of bound.
>>  	 */
>> -	if (WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp))
>> +	return !(WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp));
>> +}
>> +
>> +static inline bool alloc_trylock_allowed(void)
>
> alloc_nolock_allowed()
>
>> +{
>> +	/*
>> +	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
>> +	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
>> +	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
>> +	 * mark the task as the owner of another rt_spin_lock which will
>> +	 * confuse PI logic, so return immediately if called from hard IRQ or
>> +	 * NMI.
>> +	 *
>> +	 * Note, irqs_disabled() case is ok. This function can be called
>> +	 * from raw_spin_lock_irqsave region.
>> +	 */
>> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
>> +		return false;
>> +
>> +	/* On UP, spin_trylock() always succeeds even when it is locked */
>> +	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
>> +		return false;
>> +
>> +	/* Bailout, since _deferred_grow_zone() needs to take a lock */
>> +	if (deferred_pages_enabled())
>> +		return false;
>> +
>> +	return true;
>> +}
>> +
>> +/*
>> + * GFP flags to set for ALLOC_NOLOCK i.e. alloc_pages_nolock().
>> + *
>> + * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed.
>> + * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd
>> + * is not safe in arbitrary context.
>> + *
>> + * These two are the conditions for gfpflags_allow_spinning() being true.
>> + *
>> + * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason
>> + * to warn. Also warn would trigger printk() which is unsafe from
>> + * various contexts. We cannot use printk_deferred_enter() to mitigate,
>> + * since the running context is unknown.
>> + *
>> + * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below
>> + * is safe in any context. Also zeroing the page is mandatory for
>> + * BPF use cases.
>> + *
>> + * Though __GFP_NOMEMALLOC is not checked in the code path below,
>> + * specify it here to highlight that alloc_pages_nolock()
>> + * doesn't want to deplete reserves.
>> + */
>> +static const gfp_t gfp_nolock = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC |
>> +				__GFP_COMP;
>> +
>> +/*
>> + * This is the 'heart' of the zoned buddy allocator.
>> + */
>> +struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>> +		int preferred_nid, nodemask_t *nodemask, unsigned int alloc_flags)
>> +{
>> +	struct page *page;
>> +	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
>> +	struct alloc_context ac = { };
>> +	unsigned int fastpath_alloc_flags = alloc_flags;
>> +
>> +	/* Other flags could be supported later if needed. */
>> +	if (WARN_ON(alloc_flags & ~ALLOC_NOLOCK))
>>  		return NULL;
>>  
>> +	if (!alloc_order_allowed(gfp, order, alloc_flags))
>> +		return NULL;
>> +
>> +	if (alloc_flags & ALLOC_NOLOCK) {
>> +		VM_WARN_ON_ONCE(gfp & ~__GFP_ACCOUNT);
>> +		if (!alloc_trylock_allowed())
>> +			return NULL;
>> +		gfp |= gfp_nolock;
>
> I think we could do a
> 		fastpath_alloc_flags |= ALLOC_WMARK_MIN;
>
> to make it explicit, even though it's a no-op (the value is 0) and
> alloc_frozen_pages_nolock_noprof() didn't do it.
>
>> +	} else {
>> +		fastpath_alloc_flags |= ALLOC_WMARK_LOW;
>> +	}
>> +
>>  	gfp &= gfp_allowed_mask;
>>  	/*
>>  	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
>> @@ -5310,9 +5384,9 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>>  	fastpath_alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
>>  	fastpath_alloc_flags |= alloc_flags_nonblocking(gfp, order) & ALLOC_HIGHATOMIC;
>>  
>> -	/* First allocation attempt */
>> +	/* First allocation attempt (or, for nolock, only attempt) */
>>  	page = get_page_from_freelist(alloc_gfp, order, fastpath_alloc_flags, &ac);
>> -	if (likely(page))
>> +	if (likely(page) || (alloc_flags & ALLOC_NOLOCK))
>>  		goto out;
>>  
>>  	alloc_gfp = gfp;
>> @@ -5329,7 +5403,8 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>>  out:
>>  	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
>>  	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
>> -		free_frozen_pages(page, order);
>> +		__free_frozen_pages(page, order,
>> +				    alloc_flags & ALLOC_NOLOCK ? FPI_TRYLOCK : 0);
>>  		page = NULL;
>>  	}
>>  
>> @@ -5345,7 +5420,8 @@ struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
>>  {
>>  	struct page *page;
>>  
>> -	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask);
>> +	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask,
>> +					   ALLOC_DEFAULT);
>>  	if (page)
>>  		set_page_refcounted(page);
>>  	return page;
>> @@ -7875,80 +7951,10 @@ static bool __free_unaccepted(struct page *page)
>>  
>>  struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order)
>>  {
>> -	/*
>> -	 * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed.
>> -	 * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd
>> -	 * is not safe in arbitrary context.
>> -	 *
>> -	 * These two are the conditions for gfpflags_allow_spinning() being true.
>> -	 *
>> -	 * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason
>> -	 * to warn. Also warn would trigger printk() which is unsafe from
>> -	 * various contexts. We cannot use printk_deferred_enter() to mitigate,
>> -	 * since the running context is unknown.
>> -	 *
>> -	 * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below
>> -	 * is safe in any context. Also zeroing the page is mandatory for
>> -	 * BPF use cases.
>> -	 *
>> -	 * Though __GFP_NOMEMALLOC is not checked in the code path below,
>> -	 * specify it here to highlight that alloc_pages_nolock()
>> -	 * doesn't want to deplete reserves.
>> -	 */
>> -	gfp_t alloc_gfp = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC | __GFP_COMP
>> -			| gfp_flags;
>> -	unsigned int alloc_flags = ALLOC_NOLOCK;
>> -	struct alloc_context ac = { };
>> -	struct page *page;
>> -
>> -	VM_WARN_ON_ONCE(gfp_flags & ~__GFP_ACCOUNT);
>> -	/*
>> -	 * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is
>> -	 * unsafe in NMI. If spin_trylock() is called from hard IRQ the current
>> -	 * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will
>> -	 * mark the task as the owner of another rt_spin_lock which will
>> -	 * confuse PI logic, so return immediately if called from hard IRQ or
>> -	 * NMI.
>> -	 *
>> -	 * Note, irqs_disabled() case is ok. This function can be called
>> -	 * from raw_spin_lock_irqsave region.
>> -	 */
>> -	if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))
>> -		return NULL;
>> -
>> -	/* On UP, spin_trylock() always succeeds even when it is locked */
>> -	if (!IS_ENABLED(CONFIG_SMP) && in_nmi())
>> -		return NULL;
>> -
>> -	if (!pcp_allowed_order(order))
>> -		return NULL;
>> -
>> -	/* Bailout, since _deferred_grow_zone() needs to take a lock */
>> -	if (deferred_pages_enabled())
>> -		return NULL;
>> -
>>  	if (nid == NUMA_NO_NODE)
>>  		nid = numa_node_id();
>>  
>> -	prepare_alloc_pages(alloc_gfp, order, nid, NULL, &ac,
>> -			    &alloc_gfp, &alloc_flags);
>> -
>> -	/*
>> -	 * Best effort allocation from percpu free list.
>> -	 * If it's empty attempt to spin_trylock zone->lock.
>> -	 */
>> -	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
>> -
>> -	/* Unlike regular alloc_pages() there is no __alloc_pages_slowpath(). */
>> -
>> -	if (memcg_kmem_online() && page && (gfp_flags & __GFP_ACCOUNT) &&
>> -	    unlikely(__memcg_kmem_charge_page(page, alloc_gfp, order) != 0)) {
>> -		__free_frozen_pages(page, order, FPI_TRYLOCK);
>> -		page = NULL;
>> -	}
>> -	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
>> -	kmsan_alloc_page(page, order, alloc_gfp);
>> -	return page;
>> +	return __alloc_frozen_pages_noprof(gfp_flags, order, nid, NULL, ALLOC_NOLOCK);
>>  }
>>  /**
>>   * alloc_pages_nolock - opportunistic reentrant allocation from any context
>> diff --git a/mm/page_alloc.h b/mm/page_alloc.h
>> index 3250d44f96457..e16f905f859a7 100644
>> --- a/mm/page_alloc.h
>> +++ b/mm/page_alloc.h
>> @@ -11,6 +11,7 @@
>>  #include <linux/nodemask.h>
>>  #include <linux/types.h>
>>  
>> +#define ALLOC_DEFAULT		0
>>  /* The ALLOC_WMARK bits are used as an index to zone->watermark */
>>  #define ALLOC_WMARK_MIN		WMARK_MIN
>>  #define ALLOC_WMARK_LOW		WMARK_LOW
>> @@ -219,7 +220,7 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
>>  extern int user_min_free_kbytes;
>>  
>>  struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, int nid,
>> -		nodemask_t *nodemask);
>> +		nodemask_t *nodemask, unsigned int alloc_flags);
>>  #define __alloc_frozen_pages(...) \
>>  	alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__))
>>  void free_frozen_pages(struct page *page, unsigned int order);
>> @@ -230,7 +231,8 @@ struct page *alloc_frozen_pages_noprof(gfp_t, unsigned int order);
>>  #else
>>  static inline struct page *alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order)
>>  {
>> -	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL);
>> +	return __alloc_frozen_pages_noprof(gfp, order, numa_node_id(), NULL,
>> +					   0 /* ALLOC_DEFAULT */);
>
> Can use ALLOC_DEFAULT now.

Thanks and ack to all of these.

Will mention the ALLOC_WMARK_MIN thing in the commit message too.

[PATCH v3 06/16] mm/page_alloc: relax GFP WARN in nolock allocs

[Brendan Jackman]

This WARN forbids setting other flags than __GFP_ACCOUNT but we
unconditionally set the ones in gfp_nolock so they are certainly fine
for the caller to set.

There are other GFP flags that are almost certainly fine to set here;
Willy noted GFP_HIGHMEM, GFP_DMA, GFP_MOVABLE and GFP_HARDWALL. But,
nolock allocation is rather special, so be conservative to try and
ensure we have a chance to think carefully before nontrivial new
usecases arise.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/linux-mm/ajS96fWbG4dzP3u3@casper.infradead.org/
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 mm/page_alloc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8d409d075e3e9..9cb3f1665b41b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5355,7 +5355,8 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 		return NULL;
 
 	if (alloc_flags & ALLOC_NOLOCK) {
-		VM_WARN_ON_ONCE(gfp & ~__GFP_ACCOUNT);
+		/* Certain other flags could be supported later if needed. */
+		VM_WARN_ON_ONCE(gfp & ~(__GFP_ACCOUNT | gfp_nolock));
 		if (!alloc_trylock_allowed())
 			return NULL;
 		gfp |= gfp_nolock;

-- 
2.54.0

Re: [PATCH v3 06/16] mm/page_alloc: relax GFP WARN in nolock allocs

[Harry Yoo]

[-- Attachment #1.1: Type: text/plain, Size: 864 bytes --]



On 6/29/26 10:11 PM, Brendan Jackman wrote:
> This WARN forbids setting other flags than __GFP_ACCOUNT but we
> unconditionally set the ones in gfp_nolock so they are certainly fine
> for the caller to set.
> 
> There are other GFP flags that are almost certainly fine to set here;
> Willy noted GFP_HIGHMEM, GFP_DMA, GFP_MOVABLE and GFP_HARDWALL. But,
> nolock allocation is rather special, so be conservative to try and
> ensure we have a chance to think carefully before nontrivial new
> usecases arise.
> 
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Link: https://lore.kernel.org/linux-mm/ajS96fWbG4dzP3u3@casper.infradead.org/
> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---

Acked-by: Harry Yoo (Oracle) <harry@kernel.org>

-- 
Cheers,
Harry / Hyeonggon

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH v3 06/16] mm/page_alloc: relax GFP WARN in nolock allocs

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> This WARN forbids setting other flags than __GFP_ACCOUNT but we
> unconditionally set the ones in gfp_nolock so they are certainly fine
> for the caller to set.
> 
> There are other GFP flags that are almost certainly fine to set here;
> Willy noted GFP_HIGHMEM, GFP_DMA, GFP_MOVABLE and GFP_HARDWALL. But,
> nolock allocation is rather special, so be conservative to try and
> ensure we have a chance to think carefully before nontrivial new
> usecases arise.
> 
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Link: https://lore.kernel.org/linux-mm/ajS96fWbG4dzP3u3@casper.infradead.org/
> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

> ---
>  mm/page_alloc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 8d409d075e3e9..9cb3f1665b41b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5355,7 +5355,8 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>  		return NULL;
>  
>  	if (alloc_flags & ALLOC_NOLOCK) {
> -		VM_WARN_ON_ONCE(gfp & ~__GFP_ACCOUNT);
> +		/* Certain other flags could be supported later if needed. */
> +		VM_WARN_ON_ONCE(gfp & ~(__GFP_ACCOUNT | gfp_nolock));
>  		if (!alloc_trylock_allowed())
>  			return NULL;
>  		gfp |= gfp_nolock;
> 

[PATCH v3 07/16] mm: move some stuff to mm/page_alloc.h

[Brendan Jackman]

Some of this stuff in the public header is only used internally so
shrink the scope to avoid silently growing new users.

drain_local_pages() is still used from kernel/power/snapshot.c so that
needs to stay behind.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 include/linux/gfp.h | 26 --------------------------
 mm/page_alloc.h     | 28 ++++++++++++++++++++++++++++
 mm/vmstat.c         |  1 +
 3 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index cdf95a9f0b87c..01d6d2591f49e 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -17,28 +17,6 @@ struct mempolicy;
 #define __default_gfp(a,b,...) b
 #define default_gfp(...) __default_gfp(,##__VA_ARGS__,GFP_KERNEL)
 
-/* Convert GFP flags to their corresponding migrate type */
-#define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
-#define GFP_MOVABLE_SHIFT 3
-
-static inline int gfp_migratetype(const gfp_t gfp_flags)
-{
-	VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
-	BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
-	BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
-	BUILD_BUG_ON((___GFP_RECLAIMABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_RECLAIMABLE);
-	BUILD_BUG_ON(((___GFP_MOVABLE | ___GFP_RECLAIMABLE) >>
-		      GFP_MOVABLE_SHIFT) != MIGRATE_HIGHATOMIC);
-
-	if (unlikely(page_group_by_mobility_disabled))
-		return MIGRATE_UNMOVABLE;
-
-	/* Group based on mobility */
-	return (__force unsigned long)(gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT;
-}
-#undef GFP_MOVABLE_MASK
-#undef GFP_MOVABLE_SHIFT
-
 static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
 {
 	return !!(gfp_flags & __GFP_DIRECT_RECLAIM);
@@ -395,10 +373,6 @@ extern void free_pages(unsigned long addr, unsigned int order);
 #define __free_page(page) __free_pages((page), 0)
 #define free_page(addr) free_pages((addr), 0)
 
-void page_alloc_init_cpuhp(void);
-bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp);
-void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
-void drain_all_pages(struct zone *zone);
 void drain_local_pages(struct zone *zone);
 
 void page_alloc_init_late(void);
diff --git a/mm/page_alloc.h b/mm/page_alloc.h
index e16f905f859a7..af83764788b96 100644
--- a/mm/page_alloc.h
+++ b/mm/page_alloc.h
@@ -266,6 +266,34 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
 	return list_empty(&area->free_list[migratetype]);
 }
 
+/* Convert GFP flags to their corresponding migrate type */
+#define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
+#define GFP_MOVABLE_SHIFT 3
+
+static inline int gfp_migratetype(const gfp_t gfp_flags)
+{
+	VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+	BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
+	BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
+	BUILD_BUG_ON((___GFP_RECLAIMABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_RECLAIMABLE);
+	BUILD_BUG_ON(((___GFP_MOVABLE | ___GFP_RECLAIMABLE) >>
+		      GFP_MOVABLE_SHIFT) != MIGRATE_HIGHATOMIC);
+
+	if (unlikely(page_group_by_mobility_disabled))
+		return MIGRATE_UNMOVABLE;
+
+	/* Group based on mobility */
+	return (__force unsigned long)(gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT;
+}
+#undef GFP_MOVABLE_MASK
+#undef GFP_MOVABLE_SHIFT
+
+bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp);
+void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
+void drain_all_pages(struct zone *zone);
+void drain_local_pages(struct zone *zone);
+
+void page_alloc_init_cpuhp(void);
 void page_alloc_sysctl_init(void);
 
 #endif /* __MM_PAGE_ALLOC_H */
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 7b93fbf9af092..3b5cb1031f720 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -30,6 +30,7 @@
 #include <linux/sched/isolation.h>
 
 #include "internal.h"
+#include "page_alloc.h"
 
 #ifdef CONFIG_PROC_FS
 #ifdef CONFIG_NUMA

-- 
2.54.0

Re: [PATCH v3 07/16] mm: move some stuff to mm/page_alloc.h

[Vlastimil Babka (SUSE)]

On 6/29/26 15:11, Brendan Jackman wrote:
> Some of this stuff in the public header is only used internally so
> shrink the scope to avoid silently growing new users.
> 
> drain_local_pages() is still used from kernel/power/snapshot.c so that
> needs to stay behind.
> 
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

> ---
>  include/linux/gfp.h | 26 --------------------------
>  mm/page_alloc.h     | 28 ++++++++++++++++++++++++++++
>  mm/vmstat.c         |  1 +
>  3 files changed, 29 insertions(+), 26 deletions(-)
> 
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index cdf95a9f0b87c..01d6d2591f49e 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -17,28 +17,6 @@ struct mempolicy;
>  #define __default_gfp(a,b,...) b
>  #define default_gfp(...) __default_gfp(,##__VA_ARGS__,GFP_KERNEL)
>  
> -/* Convert GFP flags to their corresponding migrate type */
> -#define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
> -#define GFP_MOVABLE_SHIFT 3
> -
> -static inline int gfp_migratetype(const gfp_t gfp_flags)
> -{
> -	VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
> -	BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
> -	BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
> -	BUILD_BUG_ON((___GFP_RECLAIMABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_RECLAIMABLE);
> -	BUILD_BUG_ON(((___GFP_MOVABLE | ___GFP_RECLAIMABLE) >>
> -		      GFP_MOVABLE_SHIFT) != MIGRATE_HIGHATOMIC);
> -
> -	if (unlikely(page_group_by_mobility_disabled))
> -		return MIGRATE_UNMOVABLE;
> -
> -	/* Group based on mobility */
> -	return (__force unsigned long)(gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT;
> -}
> -#undef GFP_MOVABLE_MASK
> -#undef GFP_MOVABLE_SHIFT
> -
>  static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
>  {
>  	return !!(gfp_flags & __GFP_DIRECT_RECLAIM);
> @@ -395,10 +373,6 @@ extern void free_pages(unsigned long addr, unsigned int order);
>  #define __free_page(page) __free_pages((page), 0)
>  #define free_page(addr) free_pages((addr), 0)
>  
> -void page_alloc_init_cpuhp(void);
> -bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp);
> -void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
> -void drain_all_pages(struct zone *zone);
>  void drain_local_pages(struct zone *zone);
>  
>  void page_alloc_init_late(void);
> diff --git a/mm/page_alloc.h b/mm/page_alloc.h
> index e16f905f859a7..af83764788b96 100644
> --- a/mm/page_alloc.h
> +++ b/mm/page_alloc.h
> @@ -266,6 +266,34 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
>  	return list_empty(&area->free_list[migratetype]);
>  }
>  
> +/* Convert GFP flags to their corresponding migrate type */
> +#define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
> +#define GFP_MOVABLE_SHIFT 3
> +
> +static inline int gfp_migratetype(const gfp_t gfp_flags)
> +{
> +	VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
> +	BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
> +	BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
> +	BUILD_BUG_ON((___GFP_RECLAIMABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_RECLAIMABLE);
> +	BUILD_BUG_ON(((___GFP_MOVABLE | ___GFP_RECLAIMABLE) >>
> +		      GFP_MOVABLE_SHIFT) != MIGRATE_HIGHATOMIC);
> +
> +	if (unlikely(page_group_by_mobility_disabled))
> +		return MIGRATE_UNMOVABLE;
> +
> +	/* Group based on mobility */
> +	return (__force unsigned long)(gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT;
> +}
> +#undef GFP_MOVABLE_MASK
> +#undef GFP_MOVABLE_SHIFT
> +
> +bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp);
> +void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
> +void drain_all_pages(struct zone *zone);
> +void drain_local_pages(struct zone *zone);
> +
> +void page_alloc_init_cpuhp(void);
>  void page_alloc_sysctl_init(void);
>  
>  #endif /* __MM_PAGE_ALLOC_H */
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 7b93fbf9af092..3b5cb1031f720 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -30,6 +30,7 @@
>  #include <linux/sched/isolation.h>
>  
>  #include "internal.h"
> +#include "page_alloc.h"
>  
>  #ifdef CONFIG_PROC_FS
>  #ifdef CONFIG_NUMA
> 

[PATCH v3 08/16] perf/x86/intel: Use higher-level allocator API

[Brendan Jackman]

The difference between __alloc_pages_node() and alloc_pages_node() is
that the latter allows you to pass NUMA_NO_NODE.

The former is going away and the latter works fine here so switch over.

No functional change intended.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: James Clark <james.clark@linaro.org>
Assisted-by: Gemini:unknown-version
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 arch/x86/events/intel/ds.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 91a093d8cf2e7..70be80211d823 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -832,7 +832,7 @@ static void *dsalloc_pages(size_t size, gfp_t flags, int cpu)
 	int node = cpu_to_node(cpu);
 	struct page *page;
 
-	page = __alloc_pages_node(node, flags | __GFP_ZERO, order);
+	page = alloc_pages_node(node, flags | __GFP_ZERO, order);
 	return page ? page_address(page) : NULL;
 }
 
@@ -1088,9 +1088,9 @@ void init_arch_pebs_on_cpu(int cpu)
 
 	/*
 	 * 4KB-aligned pointer of the output buffer
-	 * (__alloc_pages_node() return page aligned address)
+	 * (alloc_pages_node() returns page aligned address)
 	 * Buffer Size = 4KB * 2^SIZE
-	 * contiguous physical buffer (__alloc_pages_node() with order)
+	 * contiguous physical buffer (alloc_pages_node() with order)
 	 */
 	arch_pebs_base = virt_to_phys(cpuc->pebs_vaddr) | PEBS_BUFFER_SHIFT;
 	wrmsrq_on_cpu(cpu, MSR_IA32_PEBS_BASE, arch_pebs_base);

-- 
2.54.0

[PATCH v3 09/16] KVM: VMX: Use higher-level allocator API

[Brendan Jackman]

The difference between __alloc_pages_node() and alloc_pages_node() is
that the latter allows you to pass NUMA_NO_NODE.

The former is going away and the latter works fine here so switch over.

No functional change intended.

Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Assisted-by: Gemini:unknown-version
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 arch/x86/kvm/vmx/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2325be57d3d75..ad6a7fc6a54da 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3028,7 +3028,7 @@ struct vmcs *alloc_vmcs_cpu(bool shadow, int cpu, gfp_t flags)
 	struct page *pages;
 	struct vmcs *vmcs;
 
-	pages = __alloc_pages_node(node, flags, 0);
+	pages = alloc_pages_node(node, flags, 0);
 	if (!pages)
 		return NULL;
 	vmcs = page_address(pages);

-- 
2.54.0

RE: -EXT-[PATCH v3 09/16] KVM: VMX: Use higher-level allocator API

[Soderlund, David]

Can someone please remove me from this list.  I've requested a couple of times.

  Thanks,
     David

-----Original Message-----
From: Brendan Jackman <jackmanb@google.com> 
Sent: Monday, June 29, 2026 7:12 AM
To: Andrew Morton <akpm@linux-foundation.org>; Vlastimil Babka <vbabka@kernel.org>; Suren Baghdasaryan <surenb@google.com>; Michal Hocko <mhocko@suse.com>; Johannes Weiner <hannes@cmpxchg.org>; Zi Yan <ziy@nvidia.com>; Muchun Song <muchun.song@linux.dev>; Oscar Salvador <osalvador@suse.de>; David Hildenbrand <david@kernel.org>; Lorenzo Stoakes <ljs@kernel.org>; Liam R. Howlett <liam@infradead.org>; Mike Rapoport <rppt@kernel.org>; Matthew Brost <matthew.brost@intel.com>; Joshua Hahn <joshua.hahnjy@gmail.com>; Rakie Kim <rakie.kim@sk.com>; Byungchul Park <byungchul@sk.com>; Ying Huang <ying.huang@linux.alibaba.com>; Alistair Popple <apopple@nvidia.com>; Hao Li <hao.li@linux.dev>; Christoph Lameter <cl@gentwo.org>; David Rientjes <rientjes@google.com>; Roman Gushchin <roman.gushchin@linux.dev>; Sebastian Andrzej Siewior <bigeasy@linutronix.de>; Clark Williams <clrkwllms@kernel.org>; Steven Rostedt <rostedt@goodmis.org>
Cc: Harry Yoo (Oracle) <harry@kernel.org>; Gregory Price <gourry@gourry.net>; Johannes Weiner <hannes@cmpxchg.org>; Alexei Starovoitov <ast@kernel.org>; Matthew Wilcox <willy@infradead.org>; Hao Ge <hao.ge@linux.dev>; linux-mm@kvack.org; linux-kernel@vger.kernel.org; linux-rt-devel@lists.linux.dev; Brendan Jackman <jackmanb@google.com>; Sean Christopherson <seanjc@google.com>; Paolo Bonzini <pbonzini@redhat.com>; kvm@vger.kernel.org
Subject: -EXT-[PATCH v3 09/16] KVM: VMX: Use higher-level allocator API

WARNING:  This message is from an external source.  Evaluate the message carefully BEFORE clicking on links or opening attachments.

The difference between __alloc_pages_node() and alloc_pages_node() is that the latter allows you to pass NUMA_NO_NODE.

The former is going away and the latter works fine here so switch over.

No functional change intended.

Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Assisted-by: Gemini:unknown-version
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 arch/x86/kvm/vmx/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 2325be57d3d75..ad6a7fc6a54da 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3028,7 +3028,7 @@ struct vmcs *alloc_vmcs_cpu(bool shadow, int cpu, gfp_t flags)
        struct page *pages;
        struct vmcs *vmcs;

-       pages = __alloc_pages_node(node, flags, 0);
+       pages = alloc_pages_node(node, flags, 0);
        if (!pages)
                return NULL;
        vmcs = page_address(pages);

--
2.54.0

[PATCH v3 10/16] x86/virt: Use higher-level allocator API

[Brendan Jackman]

The difference between __alloc_pages_node() and alloc_pages_node() is
that the latter allows you to pass NUMA_NO_NODE.

The former is going away and the latter works fine here so switch over.

No functional change intended.

Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Assisted-by: Gemini:unknown-version
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 arch/x86/virt/hw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/virt/hw.c b/arch/x86/virt/hw.c
index 7e9091c640be0..a236447ac7a26 100644
--- a/arch/x86/virt/hw.c
+++ b/arch/x86/virt/hw.c
@@ -196,7 +196,7 @@ static __init int __x86_vmx_init(void)
 		struct page *page;
 		struct vmcs *vmcs;
 
-		page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
+		page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
 		if (WARN_ON_ONCE(!page)) {
 			x86_vmx_exit();
 			return -ENOMEM;

-- 
2.54.0

[PATCH v3 11/16] sgi-xp: Use higher-level allocator API

[Brendan Jackman]

The difference between __alloc_pages_node() and alloc_pages_node() is
that the latter allows you to pass NUMA_NO_NODE.

The former is going away and the latter works fine here so switch over.

No functional change intended.

Cc: Robin Holt <robinmholt@gmail.com>
Cc: Steve Wahl <steve.wahl@hpe.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Assisted-by: Gemini:unknown-model
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 drivers/misc/sgi-xp/xpc_uv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
index 772c787268932..aacff70204241 100644
--- a/drivers/misc/sgi-xp/xpc_uv.c
+++ b/drivers/misc/sgi-xp/xpc_uv.c
@@ -170,7 +170,7 @@ xpc_create_gru_mq_uv(unsigned int mq_size, int cpu, char *irq_name,
 	mq->mmr_blade = uv_cpu_to_blade_id(cpu);
 
 	nid = cpu_to_node(cpu);
-	page = __alloc_pages_node(nid,
+	page = alloc_pages_node(nid,
 				      GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
 				      pg_order);
 	if (page == NULL) {

-- 
2.54.0

Re: [PATCH v3 11/16] sgi-xp: Use higher-level allocator API

[Steve Wahl]

Acked-by: Steve Wahl <steve.wahl@hpe.com>

On Mon, Jun 29, 2026 at 01:12:00PM +0000, Brendan Jackman wrote:
> The difference between __alloc_pages_node() and alloc_pages_node() is
> that the latter allows you to pass NUMA_NO_NODE.
> 
> The former is going away and the latter works fine here so switch over.
> 
> No functional change intended.
> 
> Cc: Robin Holt <robinmholt@gmail.com>
> Cc: Steve Wahl <steve.wahl@hpe.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Assisted-by: Gemini:unknown-model
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
>  drivers/misc/sgi-xp/xpc_uv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
> index 772c787268932..aacff70204241 100644
> --- a/drivers/misc/sgi-xp/xpc_uv.c
> +++ b/drivers/misc/sgi-xp/xpc_uv.c
> @@ -170,7 +170,7 @@ xpc_create_gru_mq_uv(unsigned int mq_size, int cpu, char *irq_name,
>  	mq->mmr_blade = uv_cpu_to_blade_id(cpu);
>  
>  	nid = cpu_to_node(cpu);
> -	page = __alloc_pages_node(nid,
> +	page = alloc_pages_node(nid,
>  				      GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
>  				      pg_order);
>  	if (page == NULL) {
> 
> -- 
> 2.54.0
> 

-- 
Steve Wahl, Hewlett Packard Enterprise

[PATCH v3 12/16] net/funeth: Switch to higher-level allocator API

[Brendan Jackman]

The difference between __alloc_pages_node() and alloc_pages_node() is
that the latter allows you to pass NUMA_NO_NODE.

The former is going away and the latter works fine here so switch over.

No functional change intended.

Cc: Dimitris Michailidis <dmichail@fungible.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Assisted-by: Gemini:unknown-version
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 drivers/net/ethernet/fungible/funeth/funeth_rx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/fungible/funeth/funeth_rx.c b/drivers/net/ethernet/fungible/funeth/funeth_rx.c
index 7e2584895de39..d7000017ac2bd 100644
--- a/drivers/net/ethernet/fungible/funeth/funeth_rx.c
+++ b/drivers/net/ethernet/fungible/funeth/funeth_rx.c
@@ -103,7 +103,7 @@ static int funeth_alloc_page(struct funeth_rxq *q, struct funeth_rxbuf *rb,
 	if (cache_get(q, rb))
 		return 0;
 
-	p = __alloc_pages_node(node, gfp | __GFP_NOWARN, 0);
+	p = alloc_pages_node(node, gfp | __GFP_NOWARN, 0);
 	if (unlikely(!p))
 		return -ENOMEM;
 

-- 
2.54.0

[PATCH v3 13/16] mm: Remove __alloc_pages_node()

[Brendan Jackman]

There were only a few users, which have been removed. The only advantage
of this API over alloc_pages_node() is avoiding a single conditional
branch. The disadvantages are:

1. More API surface, more sources of confusion, more maintenance.

2. Worse impact of CPU hotplug bugs: most users of __alloc_pages_node()
   were using the result of cpu_to_node(); if the CPU gets hotplugged
   out this will return NUMA_NO_NODE. If one of these paths fails to
   protect against a concurrent hotplug then page_alloc.c will use
   NUMA_NO_NODE as an index into NODE_DATA() and cause some horrible
   memory corruption or other. With alloc_pages_node(), the code might
   just work fine.

Ulterior motive: this frees up the __* variants of the allocator APIs to
serve specifically for use as mm-internal API.

Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 include/linux/gfp.h | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 01d6d2591f49e..3bf55a5f9143e 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -256,21 +256,6 @@ static inline void warn_if_node_offline(int this_node, gfp_t gfp_mask)
 	dump_stack();
 }
 
-/*
- * Allocate pages, preferring the node given as nid. The node must be valid and
- * online. For more general interface, see alloc_pages_node().
- */
-static inline struct page *
-__alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order)
-{
-	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
-	warn_if_node_offline(nid, gfp_mask);
-
-	return __alloc_pages_noprof(gfp_mask, order, nid, NULL);
-}
-
-#define  __alloc_pages_node(...)		alloc_hooks(__alloc_pages_node_noprof(__VA_ARGS__))
-
 static inline
 struct folio *__folio_alloc_node_noprof(gfp_t gfp, unsigned int order, int nid)
 {
@@ -293,7 +278,10 @@ static inline struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask,
 	if (nid == NUMA_NO_NODE)
 		nid = numa_mem_id();
 
-	return __alloc_pages_node_noprof(nid, gfp_mask, order);
+	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
+	warn_if_node_offline(nid, gfp_mask);
+
+	return __alloc_pages_noprof(gfp_mask, order, nid, NULL);
 }
 
 #define  alloc_pages_node(...)			alloc_hooks(alloc_pages_node_noprof(__VA_ARGS__))

-- 
2.54.0

[PATCH v3 14/16] mm: Move __alloc_pages() to mm/page_alloc.h

[Brendan Jackman]

It's no longer used outside of mm/.

Since this means __alloc_pages_noprof() is no longer visible from gfp.h,
this also means moving the definition of alloc_pages_node_noprof into
the .c file.

Also remove references to this API from the documentation tree -
referring to the specific function name was already questionable but
now the function is not even public it definitely seems wrong.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 Documentation/admin-guide/cgroup-v1/cpusets.rst |  2 +-
 Documentation/admin-guide/mm/transhuge.rst      |  2 +-
 include/linux/gfp.h                             | 16 +---------------
 mm/page_alloc.c                                 | 13 ++++++++++++-
 mm/page_alloc.h                                 |  4 ++++
 5 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/Documentation/admin-guide/cgroup-v1/cpusets.rst b/Documentation/admin-guide/cgroup-v1/cpusets.rst
index c7909e5ac1361..52a213aff04e5 100644
--- a/Documentation/admin-guide/cgroup-v1/cpusets.rst
+++ b/Documentation/admin-guide/cgroup-v1/cpusets.rst
@@ -284,7 +284,7 @@ take action.
 ==>
     Unless this feature is enabled by writing "1" to the special file
     /dev/cpuset/memory_pressure_enabled, the hook in the rebalance
-    code of __alloc_pages() for this metric reduces to simply noticing
+    code of the page allocator for this metric reduces to simply noticing
     that the cpuset_memory_pressure_enabled flag is zero.  So only
     systems that enable this feature will compute the metric.
 
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 23f8d13c2629d..16f37135ed80d 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -761,7 +761,7 @@ compact_fail
 	but failed.
 
 It is possible to establish how long the stalls were using the function
-tracer to record how long was spent in __alloc_pages() and
+tracer to record how long was spent in the page allocator and
 using the mm_page_alloc tracepoint to identify which allocations were
 for huge pages.
 
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 3bf55a5f9143e..4d57e9c0bf204 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -204,10 +204,6 @@ static inline void arch_free_page(struct page *page, int order) { }
 static inline void arch_alloc_page(struct page *page, int order) { }
 #endif
 
-struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
-		nodemask_t *nodemask);
-#define __alloc_pages(...)			alloc_hooks(__alloc_pages_noprof(__VA_ARGS__))
-
 struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
 		nodemask_t *nodemask);
 #define __folio_alloc(...)			alloc_hooks(__folio_alloc_noprof(__VA_ARGS__))
@@ -272,17 +268,7 @@ struct folio *__folio_alloc_node_noprof(gfp_t gfp, unsigned int order, int nid)
  * prefer the current CPU's closest node. Otherwise node must be valid and
  * online.
  */
-static inline struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask,
-						   unsigned int order)
-{
-	if (nid == NUMA_NO_NODE)
-		nid = numa_mem_id();
-
-	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
-	warn_if_node_offline(nid, gfp_mask);
-
-	return __alloc_pages_noprof(gfp_mask, order, nid, NULL);
-}
+struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order);
 
 #define  alloc_pages_node(...)			alloc_hooks(alloc_pages_node_noprof(__VA_ARGS__))
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9cb3f1665b41b..026f33f217036 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5427,7 +5427,18 @@ struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
 		set_page_refcounted(page);
 	return page;
 }
-EXPORT_SYMBOL(__alloc_pages_noprof);
+
+struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order)
+{
+	if (nid == NUMA_NO_NODE)
+		nid = numa_mem_id();
+
+	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
+	warn_if_node_offline(nid, gfp_mask);
+
+	return __alloc_pages_noprof(gfp_mask, order, nid, NULL);
+}
+EXPORT_SYMBOL(alloc_pages_node_noprof);
 
 struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
 		nodemask_t *nodemask)
diff --git a/mm/page_alloc.h b/mm/page_alloc.h
index af83764788b96..2058cbdca56e7 100644
--- a/mm/page_alloc.h
+++ b/mm/page_alloc.h
@@ -244,6 +244,10 @@ struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned
 	alloc_hooks(alloc_frozen_pages_nolock_noprof(__VA_ARGS__))
 void free_frozen_pages_nolock(struct page *page, unsigned int order);
 
+struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
+		nodemask_t *nodemask);
+#define __alloc_pages(...)			alloc_hooks(__alloc_pages_noprof(__VA_ARGS__))
+
 extern void zone_pcp_reset(struct zone *zone);
 extern void zone_pcp_disable(struct zone *zone);
 extern void zone_pcp_enable(struct zone *zone);

-- 
2.54.0

[PATCH v3 15/16] mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG

[Brendan Jackman]

Now that alloc_pages has an entrypoint that allows passing alloc_flags,
we can take advantage of this to start removing GFP flags that are only
used for mm-internal stuff.

This requires also plumbing the alloc_flags into some more of the
allocator code, in particular __alloc_pages[_noprof]() gets an
alloc_flags arg to go along with its callees, and we now need to pass
those flags deeper into the allocator so they can reach the alloc_tag
code.

No functional change intended.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 mm/alloc_tag.c       | 22 ++++++----------------
 mm/compaction.c      |  4 ++--
 mm/internal.h        |  1 -
 mm/page_alloc.c      | 42 ++++++++++++++++++++++++------------------
 mm/page_alloc.h      | 17 +++++++++++++++--
 mm/page_frag_cache.c |  4 ++--
 6 files changed, 49 insertions(+), 41 deletions(-)

diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c
index d9be1cf5187d9..a32a94e759b94 100644
--- a/mm/alloc_tag.c
+++ b/mm/alloc_tag.c
@@ -15,6 +15,8 @@
 #include <linux/vmalloc.h>
 #include <linux/kmemleak.h>
 
+#include "internal.h"
+
 #define ALLOCINFO_FILE_NAME		"allocinfo"
 #define MODULE_ALLOC_TAG_VMAP_SIZE	(100000UL * sizeof(struct alloc_tag))
 #define SECTION_START(NAME)		(CODETAG_SECTION_START_PREFIX NAME)
@@ -783,19 +785,6 @@ struct pfn_pool {
 
 #define PFN_POOL_SIZE			((PAGE_SIZE - offsetof(struct pfn_pool, pfns)) / \
 					 sizeof(unsigned long))
-
-/*
- * Skip early PFN recording for a page allocation.  Reuses the
- * %__GFP_NO_OBJ_EXT bit.  Used by __alloc_tag_add_early_pfn() to avoid
- * recursion when allocating pages for the early PFN tracking list
- * itself.
- *
- * Codetags of the pages allocated with __GFP_NO_CODETAG should be
- * cleared (via clear_page_tag_ref()) before freeing the pages to prevent
- * alloc_tag_sub_check() from triggering a warning.
- */
-#define __GFP_NO_CODETAG		__GFP_NO_OBJ_EXT
-
 static struct pfn_pool *current_pfn_pool __initdata;
 
 static void __init __alloc_tag_add_early_pfn(unsigned long pfn)
@@ -806,7 +795,8 @@ static void __init __alloc_tag_add_early_pfn(unsigned long pfn)
 	do {
 		pool = READ_ONCE(current_pfn_pool);
 		if (!pool || atomic_read(&pool->count) >= PFN_POOL_SIZE) {
-			struct page *new_page = alloc_page(__GFP_HIGH | __GFP_NO_CODETAG);
+			struct page *new_page = __alloc_pages(__GFP_HIGH, 0, numa_mem_id(),
+							      NULL, ALLOC_NO_CODETAG);
 			struct pfn_pool *new;
 
 			if (!new_page) {
@@ -837,7 +827,7 @@ typedef void alloc_tag_add_func(unsigned long pfn);
 static alloc_tag_add_func __rcu *alloc_tag_add_early_pfn_ptr __refdata =
 	RCU_INITIALIZER(__alloc_tag_add_early_pfn);
 
-void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)
+void alloc_tag_add_early_pfn(unsigned long pfn, unsigned int alloc_flags)
 {
 	alloc_tag_add_func *alloc_tag_add;
 
@@ -845,7 +835,7 @@ void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)
 		return;
 
 	/* Skip allocations for the tracking list itself to avoid recursion. */
-	if (gfp_flags & __GFP_NO_CODETAG)
+	if (alloc_flags & ALLOC_NO_CODETAG)
 		return;
 
 	rcu_read_lock();
diff --git a/mm/compaction.c b/mm/compaction.c
index 7d80735502d9a..4b2318fad4eb5 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -83,7 +83,7 @@ static inline bool is_via_compact_memory(int order) { return false; }
 
 static struct page *mark_allocated_noprof(struct page *page, unsigned int order, gfp_t gfp_flags)
 {
-	post_alloc_hook(page, order, __GFP_MOVABLE);
+	post_alloc_hook(page, order, __GFP_MOVABLE, ALLOC_DEFAULT);
 	set_page_refcounted(page);
 	return page;
 }
@@ -1851,7 +1851,7 @@ static struct folio *compaction_alloc_noprof(struct folio *src, unsigned long da
 	}
 	dst = (struct folio *)freepage;
 
-	post_alloc_hook(&dst->page, order, __GFP_MOVABLE);
+	post_alloc_hook(&dst->page, order, __GFP_MOVABLE, ALLOC_DEFAULT);
 	set_page_refcounted(&dst->page);
 	if (order)
 		prep_compound_page(&dst->page, order);
diff --git a/mm/internal.h b/mm/internal.h
index c22284f04fc9e..369c656c63fa8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1237,7 +1237,6 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
 enum ttu_flags;
 struct tlbflush_unmap_batch;
 
-
 /*
  * only for MM internal work items which do not depend on
  * any allocations or locks which might depend on allocations
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 026f33f217036..803b32e5a5e47 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1249,7 +1249,7 @@ void __clear_page_tag_ref(struct page *page)
 /* Should be called only if mem_alloc_profiling_enabled() */
 static noinline
 void __pgalloc_tag_add(struct page *page, struct task_struct *task,
-		       unsigned int nr, gfp_t gfp_flags)
+		       unsigned int nr, unsigned int alloc_flags)
 {
 	union pgtag_ref_handle handle;
 	union codetag_ref ref;
@@ -1263,17 +1263,17 @@ void __pgalloc_tag_add(struct page *page, struct task_struct *task,
 		 * page_ext is not available yet, record the pfn so we can
 		 * clear the tag ref later when page_ext is initialized.
 		 */
-		alloc_tag_add_early_pfn(page_to_pfn(page), gfp_flags);
+		alloc_tag_add_early_pfn(page_to_pfn(page), alloc_flags);
 		if (task->alloc_tag)
 			alloc_tag_set_inaccurate(task->alloc_tag);
 	}
 }
 
 static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
-				   unsigned int nr, gfp_t gfp_flags)
+				   unsigned int nr, unsigned int alloc_flags)
 {
 	if (mem_alloc_profiling_enabled())
-		__pgalloc_tag_add(page, task, nr, gfp_flags);
+		__pgalloc_tag_add(page, task, nr, alloc_flags);
 }
 
 /* Should be called only if mem_alloc_profiling_enabled() */
@@ -1810,7 +1810,7 @@ static inline bool should_skip_init(gfp_t flags)
 }
 
 inline void post_alloc_hook(struct page *page, unsigned int order,
-				gfp_t gfp_flags)
+				gfp_t gfp_flags, unsigned int alloc_flags)
 {
 	const bool zero_tags = gfp_flags & __GFP_ZEROTAGS;
 	bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) &&
@@ -1861,13 +1861,13 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 
 	set_page_owner(page, order, gfp_flags);
 	page_table_check_alloc(page, order);
-	pgalloc_tag_add(page, current, 1 << order, gfp_flags);
+	pgalloc_tag_add(page, current, 1 << order, alloc_flags);
 }
 
 static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
 							unsigned int alloc_flags)
 {
-	post_alloc_hook(page, order, gfp_flags);
+	post_alloc_hook(page, order, gfp_flags, alloc_flags);
 
 	if (order && (gfp_flags & __GFP_COMP))
 		prep_compound_page(page, order);
@@ -4791,8 +4791,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	 * The fast path uses conservative alloc_flags to succeed only until
 	 * kswapd needs to be woken up, and to avoid the cost of setting up
 	 * alloc_flags precisely. So we do that now.
+	 *
+	 * Can't just or alloc_flags if it contains WMARK bits, but those flags
+	 * shouldn't be set in ac->alloc_flags.
 	 */
-	alloc_flags = alloc_flags_slowpath(gfp_mask, order);
+	VM_WARN_ON(ac->alloc_flags & ALLOC_WMARK_MASK);
+	alloc_flags = ac->alloc_flags | alloc_flags_slowpath(gfp_mask, order);
 
 	/*
 	 * We need to recalculate the starting point for the zonelist iterator
@@ -4834,7 +4838,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
 	if (reserve_flags)
 		alloc_flags = alloc_flags_cma(gfp_mask, reserve_flags) |
-					  (alloc_flags & ALLOC_KSWAPD);
+				ac->alloc_flags | (alloc_flags & ALLOC_KSWAPD);
 
 	/*
 	 * Reset the nodemask and zonelist iterators if memory policies can be
@@ -5236,7 +5240,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
 	return nr_populated;
 
 failed:
-	page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask);
+	page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask, ALLOC_DEFAULT);
 	if (page)
 		page_array[nr_populated++] = page;
 	goto out;
@@ -5344,11 +5348,13 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 {
 	struct page *page;
 	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
-	struct alloc_context ac = { };
+	struct alloc_context ac = {
+		.alloc_flags = alloc_flags,
+	};
 	unsigned int fastpath_alloc_flags = alloc_flags;
 
 	/* Other flags could be supported later if needed. */
-	if (WARN_ON(alloc_flags & ~ALLOC_NOLOCK))
+	if (WARN_ON(alloc_flags & ~(ALLOC_NOLOCK | ALLOC_NO_CODETAG)))
 		return NULL;
 
 	if (!alloc_order_allowed(gfp, order, alloc_flags))
@@ -5417,12 +5423,12 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 EXPORT_SYMBOL(__alloc_frozen_pages_noprof);
 
 struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
-		int preferred_nid, nodemask_t *nodemask)
+		int preferred_nid, nodemask_t *nodemask, unsigned int alloc_flags)
 {
 	struct page *page;
 
 	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask,
-					   ALLOC_DEFAULT);
+					   alloc_flags);
 	if (page)
 		set_page_refcounted(page);
 	return page;
@@ -5436,7 +5442,7 @@ struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order
 	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
 	warn_if_node_offline(nid, gfp_mask);
 
-	return __alloc_pages_noprof(gfp_mask, order, nid, NULL);
+	return __alloc_pages_noprof(gfp_mask, order, nid, NULL, ALLOC_DEFAULT);
 }
 EXPORT_SYMBOL(alloc_pages_node_noprof);
 
@@ -5444,7 +5450,7 @@ struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_
 		nodemask_t *nodemask)
 {
 	struct page *page = __alloc_pages_noprof(gfp | __GFP_COMP, order,
-					preferred_nid, nodemask);
+					preferred_nid, nodemask, ALLOC_DEFAULT);
 	return page_rmappable_folio(page);
 }
 EXPORT_SYMBOL(__folio_alloc_noprof);
@@ -7126,7 +7132,7 @@ static void split_free_frozen_pages(struct list_head *list, gfp_t gfp_mask)
 		list_for_each_entry_safe(page, next, &list[order], lru) {
 			int i;
 
-			post_alloc_hook(page, order, gfp_mask);
+			post_alloc_hook(page, order, gfp_mask, ALLOC_DEFAULT);
 			if (!order)
 				continue;
 
@@ -7331,7 +7337,7 @@ int alloc_contig_frozen_range_noprof(unsigned long start, unsigned long end,
 		struct page *head = pfn_to_page(start);
 
 		check_new_pages(head, order);
-		prep_new_page(head, order, gfp_mask, 0);
+		prep_new_page(head, order, gfp_mask, ALLOC_DEFAULT);
 	} else {
 		ret = -EINVAL;
 		WARN(true, "PFN range: requested [%lu, %lu), allocated [%lu, %lu)\n",
diff --git a/mm/page_alloc.h b/mm/page_alloc.h
index 2058cbdca56e7..2614bff6795b0 100644
--- a/mm/page_alloc.h
+++ b/mm/page_alloc.h
@@ -49,6 +49,16 @@
 #define ALLOC_HIGHATOMIC	0x200 /* Allows access to MIGRATE_HIGHATOMIC */
 #define ALLOC_NOLOCK		0x400 /* Only use spin_trylock in allocation path */
 #define ALLOC_KSWAPD		0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */
+/*
+ * Skip early PFN recording for a page allocation.  Used by
+ * __alloc_tag_add_early_pfn() to avoid recursion when allocating pages for the
+ * early PFN tracking list itself.
+ *
+ * Codetags of the pages allocated with __GFP_NO_CODETAG should be
+ * cleared (via clear_page_tag_ref()) before freeing the pages to prevent
+ * alloc_tag_sub_check() from triggering a warning.
+ */
+#define ALLOC_NO_CODETAG       0x1000
 
 /* Flags that allow allocations below the min watermark. */
 #define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM)
@@ -84,6 +94,8 @@ struct alloc_context {
 	 */
 	enum zone_type highest_zoneidx;
 	bool spread_dirty_pages;
+	/* Only flags that are global to the whole allocation go here. */
+	unsigned int alloc_flags;
 };
 
 /*
@@ -214,7 +226,8 @@ static inline struct page *pageblock_pfn_to_page(unsigned long start_pfn,
 extern void __free_pages_core(struct page *page, unsigned int order,
 		enum meminit_context context);
 
-void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags);
+void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags,
+		     unsigned int alloc_flags);
 extern bool free_pages_prepare(struct page *page, unsigned int order);
 
 extern int user_min_free_kbytes;
@@ -245,7 +258,7 @@ struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned
 void free_frozen_pages_nolock(struct page *page, unsigned int order);
 
 struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
-		nodemask_t *nodemask);
+		nodemask_t *nodemask, unsigned int alloc_flags);
 #define __alloc_pages(...)			alloc_hooks(__alloc_pages_noprof(__VA_ARGS__))
 
 extern void zone_pcp_reset(struct zone *zone);
diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c
index a1077cef3a791..e63efe78b7d4b 100644
--- a/mm/page_frag_cache.c
+++ b/mm/page_frag_cache.c
@@ -57,10 +57,10 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
 	gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) |  __GFP_COMP |
 		   __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC;
 	page = __alloc_pages(gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER,
-			     numa_mem_id(), NULL);
+			     numa_mem_id(), NULL, ALLOC_DEFAULT);
 #endif
 	if (unlikely(!page)) {
-		page = __alloc_pages(gfp, 0, numa_mem_id(), NULL);
+		page = __alloc_pages(gfp, 0, numa_mem_id(), NULL, ALLOC_DEFAULT);
 		order = 0;
 	}
 

-- 
2.54.0

Re: [PATCH v3 15/16] mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG

[Hao Ge]

Hi Brendan


On 2026/6/29 21:12, Brendan Jackman wrote:
> Now that alloc_pages has an entrypoint that allows passing alloc_flags,
> we can take advantage of this to start removing GFP flags that are only
> used for mm-internal stuff.
>
> This requires also plumbing the alloc_flags into some more of the
> allocator code, in particular __alloc_pages[_noprof]() gets an
> alloc_flags arg to go along with its callees, and we now need to pass
> those flags deeper into the allocator so they can reach the alloc_tag
> code.
>
> No functional change intended.
>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
>   mm/alloc_tag.c       | 22 ++++++----------------
>   mm/compaction.c      |  4 ++--
>   mm/internal.h        |  1 -
>   mm/page_alloc.c      | 42 ++++++++++++++++++++++++------------------
>   mm/page_alloc.h      | 17 +++++++++++++++--
>   mm/page_frag_cache.c |  4 ++--
>   6 files changed, 49 insertions(+), 41 deletions(-)
>
> diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c
> index d9be1cf5187d9..a32a94e759b94 100644
> --- a/mm/alloc_tag.c
> +++ b/mm/alloc_tag.c
> @@ -15,6 +15,8 @@
>   #include <linux/vmalloc.h>
>   #include <linux/kmemleak.h>
>   
> +#include "internal.h"


Should we include page_alloc.h here, as we call __alloc_pages later in 
this file?


> +
>   #define ALLOCINFO_FILE_NAME		"allocinfo"
>   #define MODULE_ALLOC_TAG_VMAP_SIZE	(100000UL * sizeof(struct alloc_tag))
>   #define SECTION_START(NAME)		(CODETAG_SECTION_START_PREFIX NAME)
> @@ -783,19 +785,6 @@ struct pfn_pool {
>   
>   #define PFN_POOL_SIZE			((PAGE_SIZE - offsetof(struct pfn_pool, pfns)) / \
>   					 sizeof(unsigned long))
> -
> -/*
> - * Skip early PFN recording for a page allocation.  Reuses the
> - * %__GFP_NO_OBJ_EXT bit.  Used by __alloc_tag_add_early_pfn() to avoid
> - * recursion when allocating pages for the early PFN tracking list
> - * itself.
> - *
> - * Codetags of the pages allocated with __GFP_NO_CODETAG should be
> - * cleared (via clear_page_tag_ref()) before freeing the pages to prevent
> - * alloc_tag_sub_check() from triggering a warning.
> - */
> -#define __GFP_NO_CODETAG		__GFP_NO_OBJ_EXT
> -
>   static struct pfn_pool *current_pfn_pool __initdata;
>   
>   static void __init __alloc_tag_add_early_pfn(unsigned long pfn)
> @@ -806,7 +795,8 @@ static void __init __alloc_tag_add_early_pfn(unsigned long pfn)
>   	do {
>   		pool = READ_ONCE(current_pfn_pool);
>   		if (!pool || atomic_read(&pool->count) >= PFN_POOL_SIZE) {
> -			struct page *new_page = alloc_page(__GFP_HIGH | __GFP_NO_CODETAG);
> +			struct page *new_page = __alloc_pages(__GFP_HIGH, 0, numa_mem_id(),
> +							      NULL, ALLOC_NO_CODETAG);
>   			struct pfn_pool *new;
>   
>   			if (!new_page) {
> @@ -837,7 +827,7 @@ typedef void alloc_tag_add_func(unsigned long pfn);
>   static alloc_tag_add_func __rcu *alloc_tag_add_early_pfn_ptr __refdata =
>   	RCU_INITIALIZER(__alloc_tag_add_early_pfn);
>   
> -void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)
> +void alloc_tag_add_early_pfn(unsigned long pfn, unsigned int alloc_flags)


alloc_tag_add_early_pfn() has three occurrences across the codebase:

1. Definition in mm/alloc_tag.c:830:

void alloc_tag_add_early_pfn(unsigned long pfn, unsigned int alloc_flags)

2. Declaration in include/linux/alloc_tag.h:166:

void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)

3. Static inline stub in include/linux/alloc_tag.h:170:

static inline void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t 
gfp_flags) {}

This patch updates the definition in alloc_tag.c to take unsigned int 
alloc_flags,

but the two declarations in alloc_tag.h are left with the old gfp_t 
gfp_flags signature

These should be updated to match.


>   {
>   	alloc_tag_add_func *alloc_tag_add;
>   
> @@ -845,7 +835,7 @@ void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)
>   		return;
>   
>   	/* Skip allocations for the tracking list itself to avoid recursion. */
> -	if (gfp_flags & __GFP_NO_CODETAG)
> +	if (alloc_flags & ALLOC_NO_CODETAG)
>   		return;
>   
>   	rcu_read_lock();
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 7d80735502d9a..4b2318fad4eb5 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -83,7 +83,7 @@ static inline bool is_via_compact_memory(int order) { return false; }
>   
>   static struct page *mark_allocated_noprof(struct page *page, unsigned int order, gfp_t gfp_flags)
>   {
> -	post_alloc_hook(page, order, __GFP_MOVABLE);
> +	post_alloc_hook(page, order, __GFP_MOVABLE, ALLOC_DEFAULT);
>   	set_page_refcounted(page);
>   	return page;
>   }
> @@ -1851,7 +1851,7 @@ static struct folio *compaction_alloc_noprof(struct folio *src, unsigned long da
>   	}
>   	dst = (struct folio *)freepage;
>   
> -	post_alloc_hook(&dst->page, order, __GFP_MOVABLE);
> +	post_alloc_hook(&dst->page, order, __GFP_MOVABLE, ALLOC_DEFAULT);
>   	set_page_refcounted(&dst->page);
>   	if (order)
>   		prep_compound_page(&dst->page, order);
> diff --git a/mm/internal.h b/mm/internal.h
> index c22284f04fc9e..369c656c63fa8 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1237,7 +1237,6 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
>   enum ttu_flags;
>   struct tlbflush_unmap_batch;
>   
> -
>   /*
>    * only for MM internal work items which do not depend on
>    * any allocations or locks which might depend on allocations
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 026f33f217036..803b32e5a5e47 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1249,7 +1249,7 @@ void __clear_page_tag_ref(struct page *page)
>   /* Should be called only if mem_alloc_profiling_enabled() */
>   static noinline
>   void __pgalloc_tag_add(struct page *page, struct task_struct *task,
> -		       unsigned int nr, gfp_t gfp_flags)
> +		       unsigned int nr, unsigned int alloc_flags)
>   {
>   	union pgtag_ref_handle handle;
>   	union codetag_ref ref;
> @@ -1263,17 +1263,17 @@ void __pgalloc_tag_add(struct page *page, struct task_struct *task,
>   		 * page_ext is not available yet, record the pfn so we can
>   		 * clear the tag ref later when page_ext is initialized.
>   		 */
> -		alloc_tag_add_early_pfn(page_to_pfn(page), gfp_flags);
> +		alloc_tag_add_early_pfn(page_to_pfn(page), alloc_flags);
>   		if (task->alloc_tag)
>   			alloc_tag_set_inaccurate(task->alloc_tag);
>   	}
>   }
>   
>   static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
> -				   unsigned int nr, gfp_t gfp_flags)
> +				   unsigned int nr, unsigned int alloc_flags)


Same situation as alloc_tag_add_early_pfn() — the #else stub

at mm/page_alloc.c:1309 still uses gfp_t gfp_flags instead of unsigned int

alloc_flags.


>   {
>   	if (mem_alloc_profiling_enabled())
> -		__pgalloc_tag_add(page, task, nr, gfp_flags);
> +		__pgalloc_tag_add(page, task, nr, alloc_flags);
>   }
>   
>   /* Should be called only if mem_alloc_profiling_enabled() */
> @@ -1810,7 +1810,7 @@ static inline bool should_skip_init(gfp_t flags)
>   }
>   
>   inline void post_alloc_hook(struct page *page, unsigned int order,
> -				gfp_t gfp_flags)
> +				gfp_t gfp_flags, unsigned int alloc_flags)
>   {
>   	const bool zero_tags = gfp_flags & __GFP_ZEROTAGS;
>   	bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) &&
> @@ -1861,13 +1861,13 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
>   
>   	set_page_owner(page, order, gfp_flags);
>   	page_table_check_alloc(page, order);
> -	pgalloc_tag_add(page, current, 1 << order, gfp_flags);
> +	pgalloc_tag_add(page, current, 1 << order, alloc_flags);
>   }
>   
>   static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
>   							unsigned int alloc_flags)
>   {
> -	post_alloc_hook(page, order, gfp_flags);
> +	post_alloc_hook(page, order, gfp_flags, alloc_flags);
>   
>   	if (order && (gfp_flags & __GFP_COMP))
>   		prep_compound_page(page, order);
> @@ -4791,8 +4791,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>   	 * The fast path uses conservative alloc_flags to succeed only until
>   	 * kswapd needs to be woken up, and to avoid the cost of setting up
>   	 * alloc_flags precisely. So we do that now.
> +	 *
> +	 * Can't just or alloc_flags if it contains WMARK bits, but those flags
> +	 * shouldn't be set in ac->alloc_flags.
>   	 */
> -	alloc_flags = alloc_flags_slowpath(gfp_mask, order);
> +	VM_WARN_ON(ac->alloc_flags & ALLOC_WMARK_MASK);
> +	alloc_flags = ac->alloc_flags | alloc_flags_slowpath(gfp_mask, order);
>   
>   	/*
>   	 * We need to recalculate the starting point for the zonelist iterator
> @@ -4834,7 +4838,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>   	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
>   	if (reserve_flags)
>   		alloc_flags = alloc_flags_cma(gfp_mask, reserve_flags) |
> -					  (alloc_flags & ALLOC_KSWAPD);
> +				ac->alloc_flags | (alloc_flags & ALLOC_KSWAPD);
>   
>   	/*
>   	 * Reset the nodemask and zonelist iterators if memory policies can be
> @@ -5236,7 +5240,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
>   	return nr_populated;
>   
>   failed:
> -	page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask);
> +	page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask, ALLOC_DEFAULT);
>   	if (page)
>   		page_array[nr_populated++] = page;
>   	goto out;
> @@ -5344,11 +5348,13 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>   {
>   	struct page *page;
>   	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
> -	struct alloc_context ac = { };
> +	struct alloc_context ac = {
> +		.alloc_flags = alloc_flags,
> +	};
>   	unsigned int fastpath_alloc_flags = alloc_flags;
>   
>   	/* Other flags could be supported later if needed. */
> -	if (WARN_ON(alloc_flags & ~ALLOC_NOLOCK))
> +	if (WARN_ON(alloc_flags & ~(ALLOC_NOLOCK | ALLOC_NO_CODETAG)))
>   		return NULL;
>   
>   	if (!alloc_order_allowed(gfp, order, alloc_flags))
> @@ -5417,12 +5423,12 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
>   EXPORT_SYMBOL(__alloc_frozen_pages_noprof);
>   
>   struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
> -		int preferred_nid, nodemask_t *nodemask)
> +		int preferred_nid, nodemask_t *nodemask, unsigned int alloc_flags)
>   {
>   	struct page *page;
>   
>   	page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask,
> -					   ALLOC_DEFAULT);
> +					   alloc_flags);
>   	if (page)
>   		set_page_refcounted(page);
>   	return page;
> @@ -5436,7 +5442,7 @@ struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order
>   	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
>   	warn_if_node_offline(nid, gfp_mask);
>   
> -	return __alloc_pages_noprof(gfp_mask, order, nid, NULL);
> +	return __alloc_pages_noprof(gfp_mask, order, nid, NULL, ALLOC_DEFAULT);
>   }
>   EXPORT_SYMBOL(alloc_pages_node_noprof);
>   
> @@ -5444,7 +5450,7 @@ struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_
>   		nodemask_t *nodemask)
>   {
>   	struct page *page = __alloc_pages_noprof(gfp | __GFP_COMP, order,
> -					preferred_nid, nodemask);
> +					preferred_nid, nodemask, ALLOC_DEFAULT);
>   	return page_rmappable_folio(page);
>   }
>   EXPORT_SYMBOL(__folio_alloc_noprof);
> @@ -7126,7 +7132,7 @@ static void split_free_frozen_pages(struct list_head *list, gfp_t gfp_mask)
>   		list_for_each_entry_safe(page, next, &list[order], lru) {
>   			int i;
>   
> -			post_alloc_hook(page, order, gfp_mask);
> +			post_alloc_hook(page, order, gfp_mask, ALLOC_DEFAULT);
>   			if (!order)
>   				continue;
>   
> @@ -7331,7 +7337,7 @@ int alloc_contig_frozen_range_noprof(unsigned long start, unsigned long end,
>   		struct page *head = pfn_to_page(start);
>   
>   		check_new_pages(head, order);
> -		prep_new_page(head, order, gfp_mask, 0);
> +		prep_new_page(head, order, gfp_mask, ALLOC_DEFAULT);
>   	} else {
>   		ret = -EINVAL;
>   		WARN(true, "PFN range: requested [%lu, %lu), allocated [%lu, %lu)\n",
> diff --git a/mm/page_alloc.h b/mm/page_alloc.h
> index 2058cbdca56e7..2614bff6795b0 100644
> --- a/mm/page_alloc.h
> +++ b/mm/page_alloc.h
> @@ -49,6 +49,16 @@
>   #define ALLOC_HIGHATOMIC	0x200 /* Allows access to MIGRATE_HIGHATOMIC */
>   #define ALLOC_NOLOCK		0x400 /* Only use spin_trylock in allocation path */
>   #define ALLOC_KSWAPD		0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */
> +/*
> + * Skip early PFN recording for a page allocation.  Used by
> + * __alloc_tag_add_early_pfn() to avoid recursion when allocating pages for the
> + * early PFN tracking list itself.
> + *
> + * Codetags of the pages allocated with __GFP_NO_CODETAG should be
> + * cleared (via clear_page_tag_ref()) before freeing the pages to prevent
> + * alloc_tag_sub_check() from triggering a warning.
> + */


I originally wrote this lengthy comment because the logic lives inside 
alloc_tag.c.

I wanted to document all the context to avoid confusion when revisiting 
this code later on.

We've since replaced __GFP_NO_CODETAG with ALLOC_NO_CODETAG, a generic 
alloc_flags bit defined in page_alloc.h.

The original long comment is no longer accurate:

Given that, I suggest updating it to the following:

/*

  * Avoid alloc_tag recursion for internal allocations.

  * Callers must clear_page_tag_ref() before
  * freeing to avoid warnings from alloc_tag_sub_check().

  */


Thanks

Best Regards

Hao


> +#define ALLOC_NO_CODETAG       0x1000
>   
>   /* Flags that allow allocations below the min watermark. */
>   #define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM)
> @@ -84,6 +94,8 @@ struct alloc_context {
>   	 */
>   	enum zone_type highest_zoneidx;
>   	bool spread_dirty_pages;
> +	/* Only flags that are global to the whole allocation go here. */
> +	unsigned int alloc_flags;
>   };
>   
>   /*
> @@ -214,7 +226,8 @@ static inline struct page *pageblock_pfn_to_page(unsigned long start_pfn,
>   extern void __free_pages_core(struct page *page, unsigned int order,
>   		enum meminit_context context);
>   
> -void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags);
> +void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags,
> +		     unsigned int alloc_flags);
>   extern bool free_pages_prepare(struct page *page, unsigned int order);
>   
>   extern int user_min_free_kbytes;
> @@ -245,7 +258,7 @@ struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned
>   void free_frozen_pages_nolock(struct page *page, unsigned int order);
>   
>   struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, int preferred_nid,
> -		nodemask_t *nodemask);
> +		nodemask_t *nodemask, unsigned int alloc_flags);
>   #define __alloc_pages(...)			alloc_hooks(__alloc_pages_noprof(__VA_ARGS__))
>   
>   extern void zone_pcp_reset(struct zone *zone);
> diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c
> index a1077cef3a791..e63efe78b7d4b 100644
> --- a/mm/page_frag_cache.c
> +++ b/mm/page_frag_cache.c
> @@ -57,10 +57,10 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
>   	gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) |  __GFP_COMP |
>   		   __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC;
>   	page = __alloc_pages(gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER,
> -			     numa_mem_id(), NULL);
> +			     numa_mem_id(), NULL, ALLOC_DEFAULT);
>   #endif
>   	if (unlikely(!page)) {
> -		page = __alloc_pages(gfp, 0, numa_mem_id(), NULL);
> +		page = __alloc_pages(gfp, 0, numa_mem_id(), NULL, ALLOC_DEFAULT);
>   		order = 0;
>   	}
>   
>

Re: [PATCH v3 15/16] mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG

[Brendan Jackman]

On Tue Jun 30, 2026 at 1:55 AM UTC, Hao Ge wrote:
> Hi Brendan
>
>
> On 2026/6/29 21:12, Brendan Jackman wrote:
>> Now that alloc_pages has an entrypoint that allows passing alloc_flags,
>> we can take advantage of this to start removing GFP flags that are only
>> used for mm-internal stuff.
>>
>> This requires also plumbing the alloc_flags into some more of the
>> allocator code, in particular __alloc_pages[_noprof]() gets an
>> alloc_flags arg to go along with its callees, and we now need to pass
>> those flags deeper into the allocator so they can reach the alloc_tag
>> code.
>>
>> No functional change intended.
>>
>> Signed-off-by: Brendan Jackman <jackmanb@google.com>
>> ---
>>   mm/alloc_tag.c       | 22 ++++++----------------
>>   mm/compaction.c      |  4 ++--
>>   mm/internal.h        |  1 -
>>   mm/page_alloc.c      | 42 ++++++++++++++++++++++++------------------
>>   mm/page_alloc.h      | 17 +++++++++++++++--
>>   mm/page_frag_cache.c |  4 ++--
>>   6 files changed, 49 insertions(+), 41 deletions(-)
>>
>> diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c
>> index d9be1cf5187d9..a32a94e759b94 100644
>> --- a/mm/alloc_tag.c
>> +++ b/mm/alloc_tag.c
>> @@ -15,6 +15,8 @@
>>   #include <linux/vmalloc.h>
>>   #include <linux/kmemleak.h>
>>   
>> +#include "internal.h"
>
>
> Should we include page_alloc.h here, as we call __alloc_pages later in 
> this file?

Yeah, there are a few build failures due to me not doing a broad enough
build. From now on I will just wait for allmodconfig instead of trying
to be clever with my build tests, sorry about this.

Also, this suggests that I have not actually re-tested the alloc_tag
code since v3 so I must repeat the test described in my cover letter (I
just manually enable the feature and check the kernel boots) for v4.

>> +
>>   #define ALLOCINFO_FILE_NAME		"allocinfo"
>>   #define MODULE_ALLOC_TAG_VMAP_SIZE	(100000UL * sizeof(struct alloc_tag))
>>   #define SECTION_START(NAME)		(CODETAG_SECTION_START_PREFIX NAME)
>> @@ -783,19 +785,6 @@ struct pfn_pool {
>>   
>>   #define PFN_POOL_SIZE			((PAGE_SIZE - offsetof(struct pfn_pool, pfns)) / \
>>   					 sizeof(unsigned long))
>> -
>> -/*
>> - * Skip early PFN recording for a page allocation.  Reuses the
>> - * %__GFP_NO_OBJ_EXT bit.  Used by __alloc_tag_add_early_pfn() to avoid
>> - * recursion when allocating pages for the early PFN tracking list
>> - * itself.
>> - *
>> - * Codetags of the pages allocated with __GFP_NO_CODETAG should be
>> - * cleared (via clear_page_tag_ref()) before freeing the pages to prevent
>> - * alloc_tag_sub_check() from triggering a warning.
>> - */
>> -#define __GFP_NO_CODETAG		__GFP_NO_OBJ_EXT
>> -
>>   static struct pfn_pool *current_pfn_pool __initdata;
>>   
>>   static void __init __alloc_tag_add_early_pfn(unsigned long pfn)
>> @@ -806,7 +795,8 @@ static void __init __alloc_tag_add_early_pfn(unsigned long pfn)
>>   	do {
>>   		pool = READ_ONCE(current_pfn_pool);
>>   		if (!pool || atomic_read(&pool->count) >= PFN_POOL_SIZE) {
>> -			struct page *new_page = alloc_page(__GFP_HIGH | __GFP_NO_CODETAG);
>> +			struct page *new_page = __alloc_pages(__GFP_HIGH, 0, numa_mem_id(),
>> +							      NULL, ALLOC_NO_CODETAG);
>>   			struct pfn_pool *new;
>>   
>>   			if (!new_page) {
>> @@ -837,7 +827,7 @@ typedef void alloc_tag_add_func(unsigned long pfn);
>>   static alloc_tag_add_func __rcu *alloc_tag_add_early_pfn_ptr __refdata =
>>   	RCU_INITIALIZER(__alloc_tag_add_early_pfn);
>>   
>> -void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)
>> +void alloc_tag_add_early_pfn(unsigned long pfn, unsigned int alloc_flags)
>
>
> alloc_tag_add_early_pfn() has three occurrences across the codebase:
>
> 1. Definition in mm/alloc_tag.c:830:
>
> void alloc_tag_add_early_pfn(unsigned long pfn, unsigned int alloc_flags)
>
> 2. Declaration in include/linux/alloc_tag.h:166:
>
> void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags)
>
> 3. Static inline stub in include/linux/alloc_tag.h:170:
>
> static inline void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t 
> gfp_flags) {}
>
> This patch updates the definition in alloc_tag.c to take unsigned int 
> alloc_flags,
>
> but the two declarations in alloc_tag.h are left with the old gfp_t 
> gfp_flags signature
>
> These should be updated to match.

Yeah ditto, sorry about this and thanks for the review.

Re: [PATCH v3 15/16] mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG

[Brendan Jackman]

On Tue Jun 30, 2026 at 1:55 AM UTC, Hao Ge wrote:
>> +/*
>> + * Skip early PFN recording for a page allocation.  Used by
>> + * __alloc_tag_add_early_pfn() to avoid recursion when allocating pages for the
>> + * early PFN tracking list itself.
>> + *
>> + * Codetags of the pages allocated with __GFP_NO_CODETAG should be
>> + * cleared (via clear_page_tag_ref()) before freeing the pages to prevent
>> + * alloc_tag_sub_check() from triggering a warning.
>> + */
>
>
> I originally wrote this lengthy comment because the logic lives inside 
> alloc_tag.c.
>
> I wanted to document all the context to avoid confusion when revisiting 
> this code later on.
>
> We've since replaced __GFP_NO_CODETAG with ALLOC_NO_CODETAG, a generic 
> alloc_flags bit defined in page_alloc.h.
>
> The original long comment is no longer accurate:
>
> Given that, I suggest updating it to the following:
>
> /*
>
>   * Avoid alloc_tag recursion for internal allocations.
>
>   * Callers must clear_page_tag_ref() before
>   * freeing to avoid warnings from alloc_tag_sub_check().
>
>   */

Thanks for the context, pasting this in for v4!

[PATCH v3 16/16] mm: remove the __GFP_NO_OBJ_EXT flag

[Brendan Jackman]

All users of the flag are converted to SLAB_ALLOC_NO_RECURSE or
ALLOC_NO_CODETAG (from __GFP_NO_CODETAG which reused the NO_OBJ_EXT bit).
Free up the flag bit.

Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
[Rebased onto __GFP_NO_CODETAG removal]
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 tools/include/linux/gfp_types.h | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/tools/include/linux/gfp_types.h b/tools/include/linux/gfp_types.h
index 6c75df30a281d..a93b8bd200b76 100644
--- a/tools/include/linux/gfp_types.h
+++ b/tools/include/linux/gfp_types.h
@@ -55,7 +55,6 @@ enum {
 #ifdef CONFIG_LOCKDEP
 	___GFP_NOLOCKDEP_BIT,
 #endif
-	___GFP_NO_OBJ_EXT_BIT,
 	___GFP_LAST_BIT
 };
 
@@ -96,7 +95,6 @@ enum {
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
-#define ___GFP_NO_OBJ_EXT       BIT(___GFP_NO_OBJ_EXT_BIT)
 
 /*
  * Physical address zone modifiers (see linux/mmzone.h - low four bits)
@@ -137,17 +135,12 @@ enum {
  * node with no fallbacks or placement policy enforcements.
  *
  * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg.
- *
- * %__GFP_NO_OBJ_EXT causes slab allocation to have no object extension.
- * mark_obj_codetag_empty() should be called upon freeing for objects allocated
- * with this flag to indicate that their NULL tags are expected and normal.
  */
 #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE)
 #define __GFP_WRITE	((__force gfp_t)___GFP_WRITE)
 #define __GFP_HARDWALL   ((__force gfp_t)___GFP_HARDWALL)
 #define __GFP_THISNODE	((__force gfp_t)___GFP_THISNODE)
 #define __GFP_ACCOUNT	((__force gfp_t)___GFP_ACCOUNT)
-#define __GFP_NO_OBJ_EXT   ((__force gfp_t)___GFP_NO_OBJ_EXT)
 
 /**
  * DOC: Watermark modifiers

-- 
2.54.0

Re: [PATCH v3 00/16] mm: Some cleanups for page allocator APIs

[Mike Rapoport]

Hi Brendan,

On Mon, Jun 29, 2026 at 01:11:49PM +0000, Brendan Jackman wrote:
> 
> Some tweaks and cleanups for page allocator entrypoint and flags. This
> is motivated by preparation for __GFP_UNMAPPED [1] (which will probably
> become ALLOC_UNMAPPED in its next iteration), but all this is supposed
> to be an improvement to the codebase in its own right: unifying code
> paths, reducing API surface, and removing GFP flags.
> 
> Tested:
> 
> - KVM, mm, and BPF selftests in a QEMU VM
> 
> - kunit.py on x86_64
> 
> - For the ALLOC_NO_CODETAG bits I just booted a VM and read
>   /proc/allocinfo. I confirmed that if I remove ALLOC_NO_CODETAG, the
>   kernel crashes in early boot, so I was at least booting code that
>   depends on this logic.

Heads up before the full kbuild report:

CI has tested the following submission:
Status:     FAILURE
Name:       [v3,00/16] mm: Some cleanups for page allocator APIs
Patchwork:  https://patchwork.kernel.org/project/linux-mm/list/?series=1118244&state=*
Matrix:     https://github.com/linux-mm/linux-mm/actions/runs/28375636866

> I used Google's internal version of Antigravity (AI coding harness) to
> do the repetitive bits, those commits are marked with Assisted-by, the
> rest is manual.
> 
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---

-- 
Sincerely yours,
Mike.

Re: [PATCH v3 00/16] mm: Some cleanups for page allocator APIs

[Brendan Jackman]

On Mon, 29 Jun 2026 at 16:00, Mike Rapoport <rppt@kernel.org> wrote:
>
> Hi Brendan,
>
> On Mon, Jun 29, 2026 at 01:11:49PM +0000, Brendan Jackman wrote:
> >
> > Some tweaks and cleanups for page allocator entrypoint and flags. This
> > is motivated by preparation for __GFP_UNMAPPED [1] (which will probably
> > become ALLOC_UNMAPPED in its next iteration), but all this is supposed
> > to be an improvement to the codebase in its own right: unifying code
> > paths, reducing API surface, and removing GFP flags.
> >
> > Tested:
> >
> > - KVM, mm, and BPF selftests in a QEMU VM
> >
> > - kunit.py on x86_64
> >
> > - For the ALLOC_NO_CODETAG bits I just booted a VM and read
> >   /proc/allocinfo. I confirmed that if I remove ALLOC_NO_CODETAG, the
> >   kernel crashes in early boot, so I was at least booting code that
> >   depends on this logic.
>
> Heads up before the full kbuild report:
>
> CI has tested the following submission:
> Status:     FAILURE
> Name:       [v3,00/16] mm: Some cleanups for page allocator APIs
> Patchwork:  https://patchwork.kernel.org/project/linux-mm/list/?series=1118244&state=*
> Matrix:     https://github.com/linux-mm/linux-mm/actions/runs/28375636866

Agh, thanks, I broke the build for CMA.

I thought I had this covered in my local test scripts. I will fix that
first then I'll send a fixup for the patch.

Re: [PATCH v3 00/16] mm: Some cleanups for page allocator APIs

[Brendan Jackman]

On Mon, 29 Jun 2026 at 16:30, Brendan Jackman <jackmanb@google.com> wrote:
>
> On Mon, 29 Jun 2026 at 16:00, Mike Rapoport <rppt@kernel.org> wrote:
> >
> > Hi Brendan,
> >
> > On Mon, Jun 29, 2026 at 01:11:49PM +0000, Brendan Jackman wrote:
> > >
> > > Some tweaks and cleanups for page allocator entrypoint and flags. This
> > > is motivated by preparation for __GFP_UNMAPPED [1] (which will probably
> > > become ALLOC_UNMAPPED in its next iteration), but all this is supposed
> > > to be an improvement to the codebase in its own right: unifying code
> > > paths, reducing API surface, and removing GFP flags.
> > >
> > > Tested:
> > >
> > > - KVM, mm, and BPF selftests in a QEMU VM
> > >
> > > - kunit.py on x86_64
> > >
> > > - For the ALLOC_NO_CODETAG bits I just booted a VM and read
> > >   /proc/allocinfo. I confirmed that if I remove ALLOC_NO_CODETAG, the
> > >   kernel crashes in early boot, so I was at least booting code that
> > >   depends on this logic.
> >
> > Heads up before the full kbuild report:
> >
> > CI has tested the following submission:
> > Status:     FAILURE
> > Name:       [v3,00/16] mm: Some cleanups for page allocator APIs
> > Patchwork:  https://patchwork.kernel.org/project/linux-mm/list/?series=1118244&state=*
> > Matrix:     https://github.com/linux-mm/linux-mm/actions/runs/28375636866
>
> Agh, thanks, I broke the build for CMA.
>
> I thought I had this covered in my local test scripts. I will fix that
> first then I'll send a fixup for the patch.

OK my scripts are indeed checking CMA, the issue is that I didn't
build with NUMA_BALANCING.

I guess Suren was right[0] and I really should build allmodconfig (at
least vmlinux) before sending patches. I was a bit skeptical that this
was an especially useful config to build, but now I realise it just
maximises coverage, even if it does so under a pretty arbitrary
configuration.

[0] https://lore.kernel.org/all/CAJuCfpHAMaK2sZYSgS750CvgksCKEfOmLzZasXdBup+CrS-3Pg@mail.gmail.com/

Here are the fixes:

diff --git i/mm/migrate.c w/mm/migrate.c
index d9b23909d716c..8e0a6fb3f6618 100644
--- i/mm/migrate.c
+++ w/mm/migrate.c
@@ -49,6 +49,7 @@
 #include <trace/events/migrate.h>

 #include "internal.h"
+#include "page_alloc.h"
 #include "swap.h"

 static const struct movable_operations *offline_movable_ops;
diff --git i/mm/page_reporting.c w/mm/page_reporting.c
index 7418f2e500bb4..c7325704c3202 100644
--- i/mm/page_reporting.c
+++ w/mm/page_reporting.c
@@ -8,6 +8,7 @@
 #include <linux/delay.h>
 #include <linux/scatterlist.h>

+#include "page_alloc.h"
 #include "page_reporting.h"
 #include "internal.h"

diff --git i/mm/shuffle.c w/mm/shuffle.c
index fb1393b8b3a9d..82a2c7725a08a 100644
--- i/mm/shuffle.c
+++ w/mm/shuffle.c
@@ -7,6 +7,7 @@
 #include <linux/random.h>
 #include <linux/moduleparam.h>
 #include "internal.h"
+#include "page_alloc.h"
 #include "shuffle.h"

 DEFINE_STATIC_KEY_FALSE(page_alloc_shuffle_key);