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| author | Liu Shixin <liushixin2@huawei.com> | 2021-11-05 21:43:59 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-06 21:30:41 +0100 |
| commit | af1c31acc85325aec2bcc5941fb7a02e19143503 (patch) | |
| tree | 565f062886ae3d2c64093492c0ecfc094d8f4006 /mm/vmstat.c | |
| parent | selftests: vm: add KSM huge pages merging time test (diff) | |
| download | linux-af1c31acc85325aec2bcc5941fb7a02e19143503.tar.xz linux-af1c31acc85325aec2bcc5941fb7a02e19143503.zip | |
mm/vmstat: annotate data race for zone->free_area[order].nr_free
KCSAN reports a data-race on v5.10 which also exists on mainline:
BUG: KCSAN: data-race in extfrag_for_order+0x33/0x2d0
race at unknown origin, with read to 0xffff9ee9bfffab48 of 8 bytes by task 34 on cpu 1:
extfrag_for_order+0x33/0x2d0
kcompactd+0x5f0/0xce0
kthread+0x1f9/0x220
ret_from_fork+0x22/0x30
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 34 Comm: kcompactd0 Not tainted 5.10.0+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Access to zone->free_area[order].nr_free in extfrag_for_order() and
frag_show_print() is lockless. That's intentional and the stats are a
rough estimate anyway. Annotate them with data_race().
[liushixin2@huawei.com: add comments]
Link: https://lkml.kernel.org/r/20210918084655.2696522-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20210908015606.3999871-1-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
| -rw-r--r-- | mm/vmstat.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 0f4643e5324d..0fde7470368d 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1070,8 +1070,13 @@ static void fill_contig_page_info(struct zone *zone, for (order = 0; order < MAX_ORDER; order++) { unsigned long blocks; - /* Count number of free blocks */ - blocks = zone->free_area[order].nr_free; + /* + * Count number of free blocks. + * + * Access to nr_free is lockless as nr_free is used only for + * diagnostic purposes. Use data_race to avoid KCSAN warning. + */ + blocks = data_race(zone->free_area[order].nr_free); info->free_blocks_total += blocks; /* Count free base pages */ @@ -1446,7 +1451,11 @@ static void frag_show_print(struct seq_file *m, pg_data_t *pgdat, seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name); for (order = 0; order < MAX_ORDER; ++order) - seq_printf(m, "%6lu ", zone->free_area[order].nr_free); + /* + * Access to nr_free is lockless as nr_free is used only for + * printing purposes. Use data_race to avoid KCSAN warning. + */ + seq_printf(m, "%6lu ", data_race(zone->free_area[order].nr_free)); seq_putc(m, '\n'); } |