| Message ID | 20250331-mm-maxrss-data-race-v2-1-cf958e6205bf@iencinas.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm: annotate data race in update_hiwater_rss | expand |
On Mon, Mar 31, 2025 at 09:57:05PM +0200, Ignacio Encinas wrote: > mm_struct.hiwater_rss can be accessed concurrently without proper > synchronization as reported by KCSAN. > > This data race is benign as it only affects accounting information. > Annotate it with data_race() to make KCSAN happy. > > Reported-by: syzbot+419c4b42acc36c420ad3@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/67e3390c.050a0220.1ec46.0001.GAE@google.com/ > Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> > Signed-off-by: Ignacio Encinas <ignacio@iencinas.com> Looks good, thank you for the contribution! Acked-by: Pedro Falcato <pfalcato@suse.de> -- Pedro
diff --git a/include/linux/mm.h b/include/linux/mm.h index 7b1068ddcbb70b732a4f2843e6b55fd73cc3e320..572b2001588b8afe68a468840cc75cd63cd4b543 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -32,6 +32,7 @@ #include <linux/memremap.h> #include <linux/slab.h> #include <linux/cacheinfo.h> +#include <linux/compiler.h> struct mempolicy; struct anon_vma; @@ -2665,7 +2666,7 @@ static inline void update_hiwater_rss(struct mm_struct *mm) { unsigned long _rss = get_mm_rss(mm); - if ((mm)->hiwater_rss < _rss) + if (data_race(mm->hiwater_rss) < _rss) (mm)->hiwater_rss = _rss; }
mm_struct.hiwater_rss can be accessed concurrently without proper synchronization as reported by KCSAN. This data race is benign as it only affects accounting information. Annotate it with data_race() to make KCSAN happy. Reported-by: syzbot+419c4b42acc36c420ad3@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67e3390c.050a0220.1ec46.0001.GAE@google.com/ Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Signed-off-by: Ignacio Encinas <ignacio@iencinas.com> --- Changes in v2: - Annotate the actual race with data_race() instead of marking the struct field as __data_racy as suggested by Lorenzo. The commit title and description has been updated accordingly I also changed (mm) to mm as the parenthesis are no longer necessary (this particular snippet of code comes from an old macro) - Add missing Closes tag for the syzbot report - Link to v1: https://lore.kernel.org/r/20250330-mm-maxrss-data-race-v1-1-2fe0ba6b8482@iencinas.com --- include/linux/mm.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- base-commit: 3571e8b091f4270d869dda7a6cc43616c6ad6897 change-id: 20250315-mm-maxrss-data-race-6ce86b0deb14 Best regards,