* [PATCH 1/2] fs: stable_page_flags(): use BIT_ULL() for KPF flags
2026-07-02 11:06 [PATCH 0/2] fs: stable_page_flags(): use folio_test_*() helpers Jinjiang Tu
@ 2026-07-02 11:06 ` Jinjiang Tu
2026-07-02 13:10 ` David Hildenbrand (Arm)
2026-07-02 14:32 ` [PATCH 1/2] " Zi Yan
2026-07-02 11:06 ` [PATCH 2/2] fs: stable_page_flags(): use folio_test_*() helpers Jinjiang Tu
2026-07-02 12:03 ` [PATCH 0/2] " David Hildenbrand (Arm)
2 siblings, 2 replies; 7+ messages in thread
From: Jinjiang Tu @ 2026-07-02 11:06 UTC (permalink / raw)
To: akpm, ziy, david, luizcap, willy, linmiaohe, svetly.todorov,
xu.xin16, chengming.zhou, linux-fsdevel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
The stable_page_flags() function currently sets page flag bits using
"1 << KPF_xxx" for various KPF_* definitions. KPF_* may be larger than 32,
which will trigger -Wshift-count-overflow warning. All KPF_* values
currently used in "1 << KPF_xxx" are smaller than 33, so no warning is
triggered with current code. However, the later patch will cleanup
stable_page_flags() and "1 << KPF_xxx" will be used for KPF_* values larger
than 32, such as KPF_MLOCKED.
Replace all occurrences of "1 << KPF_*" with the BIT_ULL() macro to
ensure all shifts are performed on a 64-bit unsigned type. This makes
the code robust, and safe for future extension.
No functional change is intended.
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
fs/proc/page.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 7d9387143435..2717dbb0431b 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -157,7 +157,7 @@ u64 stable_page_flags(const struct page *page)
* it differentiates a memory hole from a page with no flags
*/
if (!page)
- return 1 << KPF_NOPAGE;
+ return BIT_ULL(KPF_NOPAGE);
snapshot_page(&ps, page);
folio = &ps.folio_snapshot;
@@ -170,11 +170,11 @@ u64 stable_page_flags(const struct page *page)
* pseudo flags for the well known (anonymous) memory mapped pages
*/
if (folio_mapped(folio))
- u |= 1 << KPF_MMAP;
+ u |= BIT_ULL(KPF_MMAP);
if (is_anon) {
- u |= 1 << KPF_ANON;
+ u |= BIT_ULL(KPF_ANON);
if ((mapping & FOLIO_MAPPING_FLAGS) == FOLIO_MAPPING_KSM)
- u |= 1 << KPF_KSM;
+ u |= BIT_ULL(KPF_KSM);
}
/*
@@ -184,35 +184,35 @@ u64 stable_page_flags(const struct page *page)
if (ps.idx == 0)
u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head);
else
- u |= 1 << KPF_COMPOUND_TAIL;
+ u |= BIT_ULL(KPF_COMPOUND_TAIL);
if (folio_test_hugetlb(folio))
- u |= 1 << KPF_HUGE;
+ u |= BIT_ULL(KPF_HUGE);
else if (folio_test_large(folio) &&
folio_test_large_rmappable(folio)) {
/* Note: we indicate any THPs here, not just PMD-sized ones */
- u |= 1 << KPF_THP;
+ u |= BIT_ULL(KPF_THP);
} else if (is_huge_zero_pfn(ps.pfn)) {
- u |= 1 << KPF_ZERO_PAGE;
- u |= 1 << KPF_THP;
+ u |= BIT_ULL(KPF_ZERO_PAGE);
+ u |= BIT_ULL(KPF_THP);
} else if (is_zero_pfn(ps.pfn)) {
- u |= 1 << KPF_ZERO_PAGE;
+ u |= BIT_ULL(KPF_ZERO_PAGE);
}
if (ps.flags & PAGE_SNAPSHOT_PG_BUDDY)
- u |= 1 << KPF_BUDDY;
+ u |= BIT_ULL(KPF_BUDDY);
if (folio_test_offline(folio))
- u |= 1 << KPF_OFFLINE;
+ u |= BIT_ULL(KPF_OFFLINE);
if (folio_test_pgtable(folio))
- u |= 1 << KPF_PGTABLE;
+ u |= BIT_ULL(KPF_PGTABLE);
if (folio_test_slab(folio))
- u |= 1 << KPF_SLAB;
+ u |= BIT_ULL(KPF_SLAB);
#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
u |= kpf_copy_bit(k, KPF_IDLE, PG_idle);
#else
if (ps.flags & PAGE_SNAPSHOT_PG_IDLE)
- u |= 1 << KPF_IDLE;
+ u |= BIT_ULL(KPF_IDLE);
#endif
u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
--
2.43.0
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH 2/2] fs: stable_page_flags(): use folio_test_*() helpers
2026-07-02 11:06 [PATCH 0/2] fs: stable_page_flags(): use folio_test_*() helpers Jinjiang Tu
2026-07-02 11:06 ` [PATCH 1/2] fs: stable_page_flags(): use BIT_ULL() for KPF flags Jinjiang Tu
@ 2026-07-02 11:06 ` Jinjiang Tu
2026-07-02 12:03 ` [PATCH 0/2] " David Hildenbrand (Arm)
2 siblings, 0 replies; 7+ messages in thread
From: Jinjiang Tu @ 2026-07-02 11:06 UTC (permalink / raw)
To: akpm, ziy, david, luizcap, willy, linmiaohe, svetly.todorov,
xu.xin16, chengming.zhou, linux-fsdevel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
stable_page_flags() currently accesses folio->flags.f directly. Since
commit 476d87d6a061 ("fs: stable_page_flags(): use snapshot_page()"), we
can replace these raw flag accesses with the existing folio_test_*()
helpers, thereby cleaning up the open‑coded flag handling.
For KPF_IDLE, set_ps_flags() already handles both 64‑bit and 32‑bit
cases, so the duplicate code in stable_page_flags() that deals with
CONFIG_PAGE_IDLE_FLAG for the 64‑bit case is removed.
The flag bits that has no folio_test_*() helpers are left unchanged,
including PG_owner_priv_1, PG_arch_*.
No functional change is intended.
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
fs/proc/page.c | 94 ++++++++++++++++++++++++++------------------------
1 file changed, 49 insertions(+), 45 deletions(-)
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 2717dbb0431b..0dbd46fa84ea 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -148,8 +148,6 @@ u64 stable_page_flags(const struct page *page)
const struct folio *folio;
struct page_snapshot ps;
unsigned long k;
- unsigned long mapping;
- bool is_anon;
u64 u = 0;
/*
@@ -163,17 +161,14 @@ u64 stable_page_flags(const struct page *page)
folio = &ps.folio_snapshot;
k = folio->flags.f;
- mapping = (unsigned long)folio->mapping;
- is_anon = mapping & FOLIO_MAPPING_ANON;
-
/*
* pseudo flags for the well known (anonymous) memory mapped pages
*/
if (folio_mapped(folio))
u |= BIT_ULL(KPF_MMAP);
- if (is_anon) {
+ if (folio_test_anon(folio)) {
u |= BIT_ULL(KPF_ANON);
- if ((mapping & FOLIO_MAPPING_FLAGS) == FOLIO_MAPPING_KSM)
+ if (folio_test_ksm(folio))
u |= BIT_ULL(KPF_KSM);
}
@@ -181,10 +176,12 @@ u64 stable_page_flags(const struct page *page)
* compound pages: export both head/tail info
* they together define a compound page's start/end pos and order
*/
- if (ps.idx == 0)
- u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head);
- else
+ if (ps.idx == 0) {
+ if (folio_test_head(folio))
+ u |= BIT_ULL(KPF_COMPOUND_HEAD);
+ } else {
u |= BIT_ULL(KPF_COMPOUND_TAIL);
+ }
if (folio_test_hugetlb(folio))
u |= BIT_ULL(KPF_HUGE);
else if (folio_test_large(folio) &&
@@ -201,6 +198,9 @@ u64 stable_page_flags(const struct page *page)
if (ps.flags & PAGE_SNAPSHOT_PG_BUDDY)
u |= BIT_ULL(KPF_BUDDY);
+ if (ps.flags & PAGE_SNAPSHOT_PG_IDLE)
+ u |= BIT_ULL(KPF_IDLE);
+
if (folio_test_offline(folio))
u |= BIT_ULL(KPF_OFFLINE);
if (folio_test_pgtable(folio))
@@ -208,42 +208,46 @@ u64 stable_page_flags(const struct page *page)
if (folio_test_slab(folio))
u |= BIT_ULL(KPF_SLAB);
-#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
- u |= kpf_copy_bit(k, KPF_IDLE, PG_idle);
-#else
- if (ps.flags & PAGE_SNAPSHOT_PG_IDLE)
- u |= BIT_ULL(KPF_IDLE);
-#endif
-
- u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
- u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
- u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
- u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
-
- u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
- u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
- u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
- u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
-
-#define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache))
- if ((k & SWAPCACHE) == SWAPCACHE)
- u |= 1 << KPF_SWAPCACHE;
- u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
-
- u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
- u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
-
-#ifdef CONFIG_MEMORY_FAILURE
- if (u & (1 << KPF_HUGE))
- u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
- else
- u |= kpf_copy_bit(ps.page_snapshot.flags.f, KPF_HWPOISON, PG_hwpoison);
-#endif
+ if (folio_test_locked(folio))
+ u |= BIT_ULL(KPF_LOCKED);
+ if (folio_test_dirty(folio))
+ u |= BIT_ULL(KPF_DIRTY);
+ if (folio_test_uptodate(folio))
+ u |= BIT_ULL(KPF_UPTODATE);
+ if (folio_test_writeback(folio))
+ u |= BIT_ULL(KPF_WRITEBACK);
+
+ if (folio_test_lru(folio))
+ u |= BIT_ULL(KPF_LRU);
+ if (folio_test_referenced(folio))
+ u |= BIT_ULL(KPF_REFERENCED);
+ if (folio_test_active(folio))
+ u |= BIT_ULL(KPF_ACTIVE);
+ if (folio_test_reclaim(folio))
+ u |= BIT_ULL(KPF_RECLAIM);
+
+ if (folio_test_swapcache(folio))
+ u |= BIT_ULL(KPF_SWAPCACHE);
+ if (folio_test_swapbacked(folio))
+ u |= BIT_ULL(KPF_SWAPBACKED);
+ if (folio_test_unevictable(folio))
+ u |= BIT_ULL(KPF_UNEVICTABLE);
+ if (folio_test_mlocked(folio))
+ u |= BIT_ULL(KPF_MLOCKED);
+
+ if ((folio_test_hugetlb(folio) && folio_test_hwpoison(folio))
+ || PageHWPoison(&ps.page_snapshot))
+ u |= BIT_ULL(KPF_HWPOISON);
+
+ if (folio_test_reserved(folio))
+ u |= BIT_ULL(KPF_RESERVED);
+ if (folio_test_owner_2(folio))
+ u |= BIT_ULL(KPF_OWNER_2);
+ if (folio_test_private(folio))
+ u |= BIT_ULL(KPF_PRIVATE);
+ if (folio_test_private_2(folio))
+ u |= BIT_ULL(KPF_PRIVATE_2);
- u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved);
- u |= kpf_copy_bit(k, KPF_OWNER_2, PG_owner_2);
- u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
- u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
#ifdef CONFIG_ARCH_USES_PG_ARCH_2
--
2.43.0
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH 0/2] fs: stable_page_flags(): use folio_test_*() helpers
2026-07-02 11:06 [PATCH 0/2] fs: stable_page_flags(): use folio_test_*() helpers Jinjiang Tu
2026-07-02 11:06 ` [PATCH 1/2] fs: stable_page_flags(): use BIT_ULL() for KPF flags Jinjiang Tu
2026-07-02 11:06 ` [PATCH 2/2] fs: stable_page_flags(): use folio_test_*() helpers Jinjiang Tu
@ 2026-07-02 12:03 ` David Hildenbrand (Arm)
2026-07-03 3:00 ` Jinjiang Tu
2 siblings, 1 reply; 7+ messages in thread
From: David Hildenbrand (Arm) @ 2026-07-02 12:03 UTC (permalink / raw)
To: Jinjiang Tu, akpm, ziy, luizcap, willy, linmiaohe, svetly.todorov,
xu.xin16, chengming.zhou, linux-fsdevel, linux-mm
Cc: wangkefeng.wang, sunnanyong
On 7/2/26 13:06, Jinjiang Tu wrote:
> This series cleans up stable_page_flags(), removing the remaining direct
> flag manipulation and replacing with folio helpers.
>
> Patch 1 replaces the "1 << KPF_*" expressions with BIT_ULL() marco, to
> avoid -Wshift-count-overflow warning for KPF_* values larger than 32.
>
> Patch 2 replaces direct accesses to folio->flags.f with the standard
> folio_test_*() helper functions, which cleans up stable_page_flags() and
> hides internal implementation details.
>
> This series is based on [1].
>
> [1] https://lore.kernel.org/all/20260629033122.774318-1-tujinjiang@huawei.com/
You should explain the history a bit, and why we converted to the manual checks
in the first place.
Now that we take a folio+page snapshot, the values cannot change concurrently
anymore.
--
Cheers,
David
^ permalink raw reply [flat|nested] 7+ messages in thread