Commit 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in
deactivate_slab()") suffered an update when picked up from LKML [1].Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()' created a no-op statement. Fix it by sticking to the behavior intended in the original patch [1]. In addition, make freelist_corrupted() immune to passing NULL instead of &freelist. The issue has been spotted via static analysis and code review. [1] https://lore.kernel.org/linux-mm/[email protected]/ Fixes: 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in deactivate_slab()") Cc: Andrew Morton <[email protected]> Cc: Dongli Zhang <[email protected]> Cc: <[email protected]> Signed-off-by: Eugeniu Rosca <[email protected]> --- v2: - Address the review finding from Dongli Zhang in: https://lore.kernel.org/linux-mm/[email protected]/ -------8<------- This is good to me. However, this would confuse people when CONFIG_SLUB_DEBUG is not defined. While reading the source code, people may be curious why to reset freelist when CONFIG_SLUB_DEBUG is even not defined. -------8<------- v1: - https://lore.kernel.org/linux-mm/[email protected]/ mm/slub.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 68c02b2eecd9..d4177aecedf6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -672,12 +672,12 @@ static void slab_fix(struct kmem_cache *s, char *fmt, ...) } static bool freelist_corrupted(struct kmem_cache *s, struct page *page, - void *freelist, void *nextfree) + void **freelist, void *nextfree) { if ((s->flags & SLAB_CONSISTENCY_CHECKS) && - !check_valid_pointer(s, page, nextfree)) { - object_err(s, page, freelist, "Freechain corrupt"); - freelist = NULL; + !check_valid_pointer(s, page, nextfree) && freelist) { + object_err(s, page, *freelist, "Freechain corrupt"); + *freelist = NULL; slab_fix(s, "Isolate corrupted freechain"); return true; } @@ -1494,7 +1494,7 @@ static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) {} static bool freelist_corrupted(struct kmem_cache *s, struct page *page, - void *freelist, void *nextfree) + void **freelist, void *nextfree) { return false; } @@ -2184,7 +2184,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, * 'freelist' is already corrupted. So isolate all objects * starting at 'freelist'. */ - if (freelist_corrupted(s, page, freelist, nextfree)) + if (freelist_corrupted(s, page, &freelist, nextfree)) break; do { -- 2.28.0
