FAILED: patch "[PATCH] mm, slab: clean up slab->obj_exts always" failed to apply to 6.12-stable tree

FAILED: patch "[PATCH] mm, slab: clean up slab->obj_exts always" failed to apply to 6.12-stable tree

[gregkh]

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x be8250786ca94952a19ce87f98ad9906448bc9ef
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025050521-crispy-study-e836@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From be8250786ca94952a19ce87f98ad9906448bc9ef Mon Sep 17 00:00:00 2001
From: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Date: Mon, 21 Apr 2025 15:52:32 +0800
Subject: [PATCH] mm, slab: clean up slab->obj_exts always

When memory allocation profiling is disabled at runtime or due to an
error, shutdown_mem_profiling() is called: slab->obj_exts which
previously allocated remains.
It won't be cleared by unaccount_slab() because of
mem_alloc_profiling_enabled() not true. It's incorrect, slab->obj_exts
should always be cleaned up in unaccount_slab() to avoid following error:

[...]BUG: Bad page state in process...
..
[...]page dumped because: page still charged to cgroup

[andriy.shevchenko@linux.intel.com: fold need_slab_obj_ext() into its only user]
Fixes: 21c690a349ba ("mm: introduce slabobj_ext to support slab object extensions")
Cc: stable@vger.kernel.org
Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Tested-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Link: https://patch.msgid.link/20250421075232.2165527-1-quic_zhenhuah@quicinc.com
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

diff --git a/mm/slub.c b/mm/slub.c
index dc9e729e1d26..be8b09e09d30 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2028,8 +2028,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 	return 0;
 }
 
-/* Should be called only if mem_alloc_profiling_enabled() */
-static noinline void free_slab_obj_exts(struct slab *slab)
+static inline void free_slab_obj_exts(struct slab *slab)
 {
 	struct slabobj_ext *obj_exts;
 
@@ -2049,18 +2048,6 @@ static noinline void free_slab_obj_exts(struct slab *slab)
 	slab->obj_exts = 0;
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-	if (mem_alloc_profiling_enabled())
-		return true;
-
-	/*
-	 * CONFIG_MEMCG creates vector of obj_cgroup objects conditionally
-	 * inside memcg_slab_post_alloc_hook. No other users for now.
-	 */
-	return false;
-}
-
 #else /* CONFIG_SLAB_OBJ_EXT */
 
 static inline void init_slab_obj_exts(struct slab *slab)
@@ -2077,11 +2064,6 @@ static inline void free_slab_obj_exts(struct slab *slab)
 {
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-	return false;
-}
-
 #endif /* CONFIG_SLAB_OBJ_EXT */
 
 #ifdef CONFIG_MEM_ALLOC_PROFILING
@@ -2129,7 +2111,7 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 static inline void
 alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 {
-	if (need_slab_obj_ext())
+	if (mem_alloc_profiling_enabled())
 		__alloc_tagging_slab_alloc_hook(s, object, flags);
 }
 
@@ -2601,8 +2583,12 @@ static __always_inline void account_slab(struct slab *slab, int order,
 static __always_inline void unaccount_slab(struct slab *slab, int order,
 					   struct kmem_cache *s)
 {
-	if (memcg_kmem_online() || need_slab_obj_ext())
-		free_slab_obj_exts(slab);
+	/*
+	 * The slab object extensions should now be freed regardless of
+	 * whether mem_alloc_profiling_enabled() or not because profiling
+	 * might have been disabled after slab->obj_exts got allocated.
+	 */
+	free_slab_obj_exts(slab);
 
 	mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
 			    -(PAGE_SIZE << order));

[PATCH 6.12.y] mm, slab: clean up slab->obj_exts always

[Suren Baghdasaryan]

From: Zhenhua Huang <quic_zhenhuah@quicinc.com>

When memory allocation profiling is disabled at runtime or due to an
error, shutdown_mem_profiling() is called: slab->obj_exts which
previously allocated remains.
It won't be cleared by unaccount_slab() because of
mem_alloc_profiling_enabled() not true. It's incorrect, slab->obj_exts
should always be cleaned up in unaccount_slab() to avoid following error:

[...]BUG: Bad page state in process...
..
[...]page dumped because: page still charged to cgroup

[andriy.shevchenko@linux.intel.com: fold need_slab_obj_ext() into its only user]
Fixes: 21c690a349ba ("mm: introduce slabobj_ext to support slab object extensions")
Cc: stable@vger.kernel.org
Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Tested-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Link: https://patch.msgid.link/20250421075232.2165527-1-quic_zhenhuah@quicinc.com
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
(cherry picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef)
[surenb: fixed trivial merge conflict in alloc_tagging_slab_alloc_hook(),
skipped inlining free_slab_obj_exts() as it's already inline in 6.12]
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 mm/slub.c | 27 +++++++--------------------
 1 file changed, 7 insertions(+), 20 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index c26d9cd107cc..66f86e532818 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2035,18 +2035,6 @@ static inline void free_slab_obj_exts(struct slab *slab)
 	slab->obj_exts = 0;
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-	if (mem_alloc_profiling_enabled())
-		return true;
-
-	/*
-	 * CONFIG_MEMCG creates vector of obj_cgroup objects conditionally
-	 * inside memcg_slab_post_alloc_hook. No other users for now.
-	 */
-	return false;
-}
-
 #else /* CONFIG_SLAB_OBJ_EXT */
 
 static inline void init_slab_obj_exts(struct slab *slab)
@@ -2063,11 +2051,6 @@ static inline void free_slab_obj_exts(struct slab *slab)
 {
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-	return false;
-}
-
 #endif /* CONFIG_SLAB_OBJ_EXT */
 
 #ifdef CONFIG_MEM_ALLOC_PROFILING
@@ -2099,7 +2082,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
 static inline void
 alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 {
-	if (need_slab_obj_ext()) {
+	if (mem_alloc_profiling_enabled()) {
 		struct slabobj_ext *obj_exts;
 
 		obj_exts = prepare_slab_obj_exts_hook(s, flags, object);
@@ -2577,8 +2560,12 @@ static __always_inline void account_slab(struct slab *slab, int order,
 static __always_inline void unaccount_slab(struct slab *slab, int order,
 					   struct kmem_cache *s)
 {
-	if (memcg_kmem_online() || need_slab_obj_ext())
-		free_slab_obj_exts(slab);
+	/*
+	 * The slab object extensions should now be freed regardless of
+	 * whether mem_alloc_profiling_enabled() or not because profiling
+	 * might have been disabled after slab->obj_exts got allocated.
+	 */
+	free_slab_obj_exts(slab);
 
 	mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
 			    -(PAGE_SIZE << order));
-- 
2.49.0.967.g6a0df3ecc3-goog

Re: [PATCH 6.12.y] mm, slab: clean up slab->obj_exts always

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: be8250786ca94952a19ce87f98ad9906448bc9ef

WARNING: Author mismatch between patch and found commit:
Backport author: Suren Baghdasaryan<surenb@google.com>
Commit author: Zhenhua Huang<quic_zhenhuah@quicinc.com>

Status in newer kernel trees:
6.14.y | Present (different SHA1: 94107e5aed93)

Note: The patch differs from the upstream commit:
---
1:  be8250786ca94 ! 1:  86ffacf03afed mm, slab: clean up slab->obj_exts always
    @@ Commit message
         Acked-by: Suren Baghdasaryan <surenb@google.com>
         Link: https://patch.msgid.link/20250421075232.2165527-1-quic_zhenhuah@quicinc.com
         Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
    +    (cherry picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef)
    +    [surenb: fixed trivial merge conflict in alloc_tagging_slab_alloc_hook(),
    +    skipped inlining free_slab_obj_exts() as it's already inline in 6.12]
    +    Signed-off-by: Suren Baghdasaryan <surenb@google.com>
     
      ## mm/slub.c ##
    -@@ mm/slub.c: int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
    - 	return 0;
    - }
    - 
    --/* Should be called only if mem_alloc_profiling_enabled() */
    --static noinline void free_slab_obj_exts(struct slab *slab)
    -+static inline void free_slab_obj_exts(struct slab *slab)
    - {
    - 	struct slabobj_ext *obj_exts;
    - 
    -@@ mm/slub.c: static noinline void free_slab_obj_exts(struct slab *slab)
    +@@ mm/slub.c: static inline void free_slab_obj_exts(struct slab *slab)
      	slab->obj_exts = 0;
      }
      
    @@ mm/slub.c: static inline void free_slab_obj_exts(struct slab *slab)
      #endif /* CONFIG_SLAB_OBJ_EXT */
      
      #ifdef CONFIG_MEM_ALLOC_PROFILING
    -@@ mm/slub.c: __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
    +@@ mm/slub.c: prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
      static inline void
      alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
      {
    --	if (need_slab_obj_ext())
    -+	if (mem_alloc_profiling_enabled())
    - 		__alloc_tagging_slab_alloc_hook(s, object, flags);
    - }
    +-	if (need_slab_obj_ext()) {
    ++	if (mem_alloc_profiling_enabled()) {
    + 		struct slabobj_ext *obj_exts;
      
    + 		obj_exts = prepare_slab_obj_exts_hook(s, flags, object);
     @@ mm/slub.c: static __always_inline void account_slab(struct slab *slab, int order,
      static __always_inline void unaccount_slab(struct slab *slab, int order,
      					   struct kmem_cache *s)
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Success    |  Success   |

Re: [PATCH 6.12.y] mm, slab: clean up slab->obj_exts always

[Suren Baghdasaryan]

On Thu, May 8, 2025 at 4:18 PM Sasha Levin <sashal@kernel.org> wrote:
>
> [ Sasha's backport helper bot ]
>
> Hi,
>
> Summary of potential issues:
> ⚠️ Found matching upstream commit but patch is missing proper reference to it

Not sure why "patch is missing proper reference to it". I see (cherry
picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef) in place.
Did I miss something?

>
> Found matching upstream commit: be8250786ca94952a19ce87f98ad9906448bc9ef
>
> WARNING: Author mismatch between patch and found commit:
> Backport author: Suren Baghdasaryan<surenb@google.com>
> Commit author: Zhenhua Huang<quic_zhenhuah@quicinc.com>
>
> Status in newer kernel trees:
> 6.14.y | Present (different SHA1: 94107e5aed93)
>
> Note: The patch differs from the upstream commit:

Yep, this is expected as I had to make changes when backporting.

> ---
> 1:  be8250786ca94 ! 1:  86ffacf03afed mm, slab: clean up slab->obj_exts always
>     @@ Commit message
>          Acked-by: Suren Baghdasaryan <surenb@google.com>
>          Link: https://patch.msgid.link/20250421075232.2165527-1-quic_zhenhuah@quicinc.com
>          Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>     +    (cherry picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef)
>     +    [surenb: fixed trivial merge conflict in alloc_tagging_slab_alloc_hook(),
>     +    skipped inlining free_slab_obj_exts() as it's already inline in 6.12]

And the changes are documented above.

>     +    Signed-off-by: Suren Baghdasaryan <surenb@google.com>
>
>       ## mm/slub.c ##
>     -@@ mm/slub.c: int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
>     -   return 0;
>     - }
>     -
>     --/* Should be called only if mem_alloc_profiling_enabled() */
>     --static noinline void free_slab_obj_exts(struct slab *slab)
>     -+static inline void free_slab_obj_exts(struct slab *slab)
>     - {
>     -   struct slabobj_ext *obj_exts;
>     -
>     -@@ mm/slub.c: static noinline void free_slab_obj_exts(struct slab *slab)
>     +@@ mm/slub.c: static inline void free_slab_obj_exts(struct slab *slab)
>         slab->obj_exts = 0;
>       }
>
>     @@ mm/slub.c: static inline void free_slab_obj_exts(struct slab *slab)
>       #endif /* CONFIG_SLAB_OBJ_EXT */
>
>       #ifdef CONFIG_MEM_ALLOC_PROFILING
>     -@@ mm/slub.c: __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
>     +@@ mm/slub.c: prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
>       static inline void
>       alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
>       {
>     --  if (need_slab_obj_ext())
>     -+  if (mem_alloc_profiling_enabled())
>     -           __alloc_tagging_slab_alloc_hook(s, object, flags);
>     - }
>     +-  if (need_slab_obj_ext()) {
>     ++  if (mem_alloc_profiling_enabled()) {
>     +           struct slabobj_ext *obj_exts;
>
>     +           obj_exts = prepare_slab_obj_exts_hook(s, flags, object);
>      @@ mm/slub.c: static __always_inline void account_slab(struct slab *slab, int order,
>       static __always_inline void unaccount_slab(struct slab *slab, int order,
>                                            struct kmem_cache *s)
> ---
>
> Results of testing on various branches:
>
> | Branch                    | Patch Apply | Build Test |
> |---------------------------|-------------|------------|
> | stable/linux-6.12.y       |  Success    |  Success   |

Re: [PATCH 6.12.y] mm, slab: clean up slab->obj_exts always

[Sasha Levin]

On Thu, May 08, 2025 at 05:04:45PM +0000, Suren Baghdasaryan wrote:
>On Thu, May 8, 2025 at 4:18 PM Sasha Levin <sashal@kernel.org> wrote:
>>
>> [ Sasha's backport helper bot ]
>>
>> Hi,
>>
>> Summary of potential issues:
>> ⚠️ Found matching upstream commit but patch is missing proper reference to it
>
>Not sure why "patch is missing proper reference to it". I see (cherry
>picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef) in place.
>Did I miss something?

It tries to find one of the references described in the docs for
submitting stuff to stable@:

	https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-3

-- 
Thanks,
Sasha

Re: [PATCH 6.12.y] mm, slab: clean up slab->obj_exts always

[Suren Baghdasaryan]

On Thu, May 8, 2025 at 5:15 PM Sasha Levin <sashal@kernel.org> wrote:
>
> On Thu, May 08, 2025 at 05:04:45PM +0000, Suren Baghdasaryan wrote:
> >On Thu, May 8, 2025 at 4:18 PM Sasha Levin <sashal@kernel.org> wrote:
> >>
> >> [ Sasha's backport helper bot ]
> >>
> >> Hi,
> >>
> >> Summary of potential issues:
> >> ⚠️ Found matching upstream commit but patch is missing proper reference to it
> >
> >Not sure why "patch is missing proper reference to it". I see (cherry
> >picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef) in place.
> >Did I miss something?
>
> It tries to find one of the references described in the docs for
> submitting stuff to stable@:
>
>         https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-3

Ah, I see now what I missed. Thanks!
Would you be able to add the reference or should I repost the backports?

>
> --
> Thanks,
> Sasha

Re: [PATCH 6.12.y] mm, slab: clean up slab->obj_exts always

[Greg KH]

On Thu, May 08, 2025 at 06:14:26PM +0000, Suren Baghdasaryan wrote:
> On Thu, May 8, 2025 at 5:15 PM Sasha Levin <sashal@kernel.org> wrote:
> >
> > On Thu, May 08, 2025 at 05:04:45PM +0000, Suren Baghdasaryan wrote:
> > >On Thu, May 8, 2025 at 4:18 PM Sasha Levin <sashal@kernel.org> wrote:
> > >>
> > >> [ Sasha's backport helper bot ]
> > >>
> > >> Hi,
> > >>
> > >> Summary of potential issues:
> > >> ⚠️ Found matching upstream commit but patch is missing proper reference to it
> > >
> > >Not sure why "patch is missing proper reference to it". I see (cherry
> > >picked from commit be8250786ca94952a19ce87f98ad9906448bc9ef) in place.
> > >Did I miss something?
> >
> > It tries to find one of the references described in the docs for
> > submitting stuff to stable@:
> >
> >         https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-3
> 
> Ah, I see now what I missed. Thanks!
> Would you be able to add the reference or should I repost the backports?

No need, it's already in the queue for the next round of stable releases
in a few hours.

greg k-h