The patch titled Subject: alloc_tag: fix set_codetag_empty() when !CONFIG_MEM_ALLOC_PROFILING_DEBUG has been added to the -mm mm-hotfixes-unstable branch. Its filename is alloc_tag-fix-set_codetag_empty-when-config_mem_alloc_profiling_debug.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Suren Baghdasaryan surenb@google.com Subject: alloc_tag: fix set_codetag_empty() when !CONFIG_MEM_ALLOC_PROFILING_DEBUG Date: Fri, 29 Nov 2024 16:14:23 -0800

It was recently noticed that set_codetag_empty() might be used not only to mark NULL alloctag references as empty to avoid warnings but also to reset valid tags (in clear_page_tag_ref()). Since set_codetag_empty() is defined as NOOP for CONFIG_MEM_ALLOC_PROFILING_DEBUG=n, such use of set_codetag_empty() leads to subtle bugs. Fix set_codetag_empty() for CONFIG_MEM_ALLOC_PROFILING_DEBUG=n to reset the tag reference.

Link: https://lkml.kernel.org/r/20241130001423.1114965-2-surenb@google.com Fixes: a8fc28dad6d5 ("alloc_tag: introduce clear_page_tag_ref() helper function") Signed-off-by: Suren Baghdasaryan surenb@google.com Reported-by: David Wang 00107082@163.com Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@163.com/ Cc: David Wang 00107082@163.com Cc: Kent Overstreet kent.overstreet@linux.dev Cc: Mike Rapoport (Microsoft) rppt@kernel.org Cc: Pasha Tatashin pasha.tatashin@soleen.com Cc: Sourav Panda souravpanda@google.com Cc: Yu Zhao yuzhao@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

include/linux/alloc_tag.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/include/linux/alloc_tag.h~alloc_tag-fix-set_codetag_empty-when-config_mem_alloc_profiling_debug +++ a/include/linux/alloc_tag.h @@ -63,7 +63,12 @@ static inline void set_codetag_empty(uni #else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */

static inline bool is_codetag_empty(union codetag_ref *ref) { return false; } -static inline void set_codetag_empty(union codetag_ref *ref) {} + +static inline void set_codetag_empty(union codetag_ref *ref) +{ + if (ref) + ref->ct = NULL; +}

#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */

_

Patches currently in -mm which might be from surenb@google.com are

alloc_tag-fix-module-allocation-tags-populated-area-calculation.patch alloc_tag-fix-set_codetag_empty-when-config_mem_alloc_profiling_debug.patch mm-convert-mm_lock_seq-to-a-proper-seqcount.patch mm-introduce-mmap_lock_speculation_beginend.patch