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| author | Hui Zhu <zhuhui@kylinos.cn> | 2026-06-30 15:08:10 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-07-25 21:49:15 -0700 |
| commit | 4190b262f7dd5605357aaac998204126e6733ceb (patch) | |
| tree | d396ab70a256f2044e7c9a98875905ce9587aff8 /include/asm-generic | |
| parent | 52c7b829954c20d68626aac6dae3e9bd58531377 (diff) | |
| download | linux-next-4190b262f7dd5605357aaac998204126e6733ceb.tar.gz linux-next-4190b262f7dd5605357aaac998204126e6733ceb.zip | |
mm: fix ASSERT_EXCLUSIVE_BITS by passing memdesc_flags_t by pointer
KCSAN reports a data race between page_to_nid()/folio_pgdat() reading
page->flags and folio_trylock()/folio_lock() concurrently doing
test_and_set_bit_lock(PG_locked, ...) on the same word, e.g.:
BUG: KCSAN: data-race in __lruvec_stat_mod_folio / shmem_get_folio_gfp
The race is benign: nid/zone bits are set once at page init and never
overlap with PG_locked. However, ASSERT_EXCLUSIVE_BITS() inside
memdesc_nid/zonenum() was checking a by-value copy of the flags word, not
the live page->flags, so it failed to annotate the real access.
Change memdesc_nid(), memdesc_zonenum(), memdesc_section(), and
memdesc_is_zone_device() to take a const memdesc_flags_t * and update all
callers to pass &page->flags / &folio->flags, so ASSERT_EXCLUSIVE_BITS()
operates on the actual shared word.
Guard the ASSERT_EXCLUSIVE_BITS() call in memdesc_zonenum() under
ZONES_WIDTH != 0 to avoid a zero-mask check on configs where the zone
field is absent. memdesc_section() needs no such guard, since
SECTIONS_WIDTH is never 0 wherever SECTION_IN_PAGE_FLAGS is defined.
Under CONFIG_NUMA=n, memdesc_nid() itself is stubbed to "return 0" instead
of reading page->flags, since NODES_MASK is 0 and the check can never
fire; page_to_nid()/folio_nid() now just call memdesc_nid()
unconditionally and rely on that stub, instead of duplicating the
CONFIG_NUMA split at each call site.
Link: https://lore.kernel.org/20260630070810.470763-1-hui.zhu@linux.dev
Signed-off-by: Hui Zhu <zhuhui@kylinos.cn>
Co-developed-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/asm-generic')
| -rw-r--r-- | include/asm-generic/memory_model.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h index fd74de50b054..c6b4eafaf4cb 100644 --- a/include/asm-generic/memory_model.h +++ b/include/asm-generic/memory_model.h @@ -53,7 +53,7 @@ static inline int pfn_valid(unsigned long pfn) */ #define __page_to_pfn(pg) \ ({ const struct page *__pg = (pg); \ - int __sec = memdesc_section(__pg->flags); \ + int __sec = memdesc_section(&__pg->flags); \ (unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); \ }) |