6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Suren Baghdasaryan <surenb@xxxxxxxxxx> commit 60da7445a142bd15e67f3cda915497781c3f781f upstream. 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@xxxxxxxxxx Fixes: a8fc28dad6d5 ("alloc_tag: introduce clear_page_tag_ref() helper function") Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> Reported-by: David Wang <00107082@xxxxxxx> Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@xxxxxxx/ Cc: David Wang <00107082@xxxxxxx> Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx> Cc: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx> Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx> Cc: Sourav Panda <souravpanda@xxxxxxxxxx> Cc: Yu Zhao <yuzhao@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/alloc_tag.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -48,7 +48,12 @@ 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 */
