| Message ID | 20241213013332.89910-1-00107082@163.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] mm/codetag: clear tags before swap | expand |
On Fri, 13 Dec 2024 09:33:32 +0800 David Wang <00107082@163.com> wrote: > 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). > > 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 This points at 51f43d5d82ed ("mm/codetag: swap tags when migrate pages"), which had Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") had Fixes: dcfe378c81f7 ("lib: introduce support for page allocation tagging") Cc: <stable@vger.kernel.org> And I'm thinking that this fix should have Fixes: 51f43d5d82ed ("mm/codetag: swap tags when migrate pages") Cc: <stable@vger.kernel.org>
On Thu, Dec 12, 2024 at 8:12 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Fri, 13 Dec 2024 09:33:32 +0800 David Wang <00107082@163.com> wrote: > > > 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). > > > > 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 > > This points at > > 51f43d5d82ed ("mm/codetag: swap tags when migrate pages"), which had > Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") > > e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") had > Fixes: dcfe378c81f7 ("lib: introduce support for page allocation tagging") > Cc: <stable@vger.kernel.org> > > And I'm thinking that this fix should have > Fixes: 51f43d5d82ed ("mm/codetag: swap tags when migrate pages") > Cc: <stable@vger.kernel.org> Yes, that is correct. Sorry for missing that. >
diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h index 7c0786bdf9af..cba024bf2db3 100644 --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -135,7 +135,7 @@ static inline struct alloc_tag_counters alloc_tag_read(struct alloc_tag *tag) #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); diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index 35f7560a309a..3a0413462e9f 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -209,6 +209,13 @@ void pgalloc_tag_swap(struct folio *new, struct folio *old) 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);