From: Suren Baghdasaryan Date: Thu, 11 Jul 2024 22:04:57 +0000 (-0700) Subject: alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting X-Git-Tag: v6.11-rc1~85^2~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6ab42fe21c84d72da752923b4bd7075344f4a362;p=thirdparty%2Fkernel%2Flinux.git alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting pgalloc_tag_sub() might call page_ext_put() using a page different from the one used in page_ext_get() call. This does not pose an issue since page_ext_put() ignores this parameter as long as it's non-NULL but technically this is wrong. Fix it by storing the original page used in page_ext_get() and passing it to page_ext_put(). Link: https://lkml.kernel.org/r/20240711220457.1751071-3-surenb@google.com Fixes: be25d1d4e822 ("mm: create new codetag references during page splitting") Signed-off-by: Suren Baghdasaryan Cc: Kees Cook Cc: Kent Overstreet Cc: Pasha Tatashin Cc: Sourav Panda Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h index acb1e9ce79815..18cd0c0c73d93 100644 --- a/include/linux/pgalloc_tag.h +++ b/include/linux/pgalloc_tag.h @@ -71,6 +71,7 @@ static inline void pgalloc_tag_sub(struct page *page, unsigned int nr) static inline void pgalloc_tag_split(struct page *page, unsigned int nr) { int i; + struct page_ext *first_page_ext; struct page_ext *page_ext; union codetag_ref *ref; struct alloc_tag *tag; @@ -78,7 +79,7 @@ static inline void pgalloc_tag_split(struct page *page, unsigned int nr) if (!mem_alloc_profiling_enabled()) return; - page_ext = page_ext_get(page); + first_page_ext = page_ext = page_ext_get(page); if (unlikely(!page_ext)) return; @@ -94,7 +95,7 @@ static inline void pgalloc_tag_split(struct page *page, unsigned int nr) page_ext = page_ext_next(page_ext); } out: - page_ext_put(page_ext); + page_ext_put(first_page_ext); } static inline struct alloc_tag *pgalloc_tag_get(struct page *page)