Commit 6ab42fe2 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Andrew Morton
Browse files

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: be25d1d4 ("mm: create new codetag references during page splitting")
Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent fd8acc00

include/linux/pgalloc_tag.h

+3 −2
Original line number Diff line number Diff line
@@ -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)