The patch titled Subject: mm/codetag: clear tags before swap has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-codetag-clear-tags-before-swap.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
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------------------------------------------------------ From: David Wang 00107082@163.com Subject: mm/codetag: clear tags before swap Date: Fri, 13 Dec 2024 09:33:32 +0800
When CONFIG_MEM_ALLOC_PROFILING_DEBUG is set, kernel WARN would be triggered when calling __alloc_tag_ref_set() during swap:
alloc_tag was not cleared (got tag for mm/filemap.c:1951) WARNING: CPU: 0 PID: 816 at ./include/linux/alloc_tag.h...
Clear code tags before swap can fix the warning. And this patch also fix a potential invalid address dereference in alloc_tag_add_check() when CONFIG_MEM_ALLOC_PROFILING_DEBUG is set and ref->ct is CODETAG_EMPTY, which is defined as ((void *)1).
Link: https://lkml.kernel.org/r/20241213013332.89910-1-00107082@163.com Fixes: 51f43d5d82ed ("mm/codetag: swap tags when migrate pages") Signed-off-by: David Wang 00107082@163.com Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202412112227.df61ebb-lkp@intel.com Acked-by: Suren Baghdasaryan surenb@google.com Cc: Kent Overstreet kent.overstreet@linux.dev 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 | 2 +- lib/alloc_tag.c | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-)
--- a/include/linux/alloc_tag.h~mm-codetag-clear-tags-before-swap +++ a/include/linux/alloc_tag.h @@ -140,7 +140,7 @@ static inline struct alloc_tag_counters #ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG static inline void alloc_tag_add_check(union codetag_ref *ref, struct alloc_tag *tag) { - WARN_ONCE(ref && ref->ct, + WARN_ONCE(ref && ref->ct && !is_codetag_empty(ref), "alloc_tag was not cleared (got tag for %s:%u)\n", ref->ct->filename, ref->ct->lineno);
--- a/lib/alloc_tag.c~mm-codetag-clear-tags-before-swap +++ a/lib/alloc_tag.c @@ -209,6 +209,13 @@ void pgalloc_tag_swap(struct folio *new, return; }
+ /* + * Clear tag references to avoid debug warning when using + * __alloc_tag_ref_set() with non-empty reference. + */ + set_codetag_empty(&ref_old); + set_codetag_empty(&ref_new); + /* swap tags */ __alloc_tag_ref_set(&ref_old, tag_new); update_page_tag_ref(handle_old, &ref_old); _
Patches currently in -mm which might be from 00107082@163.com are
mm-codetag-clear-tags-before-swap.patch