The patch titled
Subject: mm/rmap: annotate a data race at tlb_flush_batched
has been added to the -mm tree. Its filename is
mm-rmap-annotate-a-data-race-at-tlb_flush_batched.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-rmap-annotate-a-data-race-at-tlb_flush_batched.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-rmap-annotate-a-data-race-at-tlb_flush_batched.patch
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------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: mm/rmap: annotate a data race at tlb_flush_batched
mm->tlb_flush_batched could be accessed concurrently as noticed by
KCSAN,
BUG: KCSAN: data-race in flush_tlb_batched_pending / try_to_unmap_one
write to 0xffff93f754880bd0 of 1 bytes by task 822 on cpu 6:
try_to_unmap_one+0x59a/0x1ab0
set_tlb_ubc_flush_pending at mm/rmap.c:635
(inlined by) try_to_unmap_one at mm/rmap.c:1538
rmap_walk_anon+0x296/0x650
rmap_walk+0xdf/0x100
try_to_unmap+0x18a/0x2f0
shrink_page_list+0xef6/0x2870
shrink_inactive_list+0x316/0x880
shrink_lruvec+0x8dc/0x1380
shrink_node+0x317/0xd80
balance_pgdat+0x652/0xd90
kswapd+0x396/0x8d0
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
read to 0xffff93f754880bd0 of 1 bytes by task 6364 on cpu 4:
flush_tlb_batched_pending+0x29/0x90
flush_tlb_batched_pending at mm/rmap.c:682
change_p4d_range+0x5dd/0x1030
change_pte_range at mm/mprotect.c:44
(inlined by) change_pmd_range at mm/mprotect.c:212
(inlined by) change_pud_range at mm/mprotect.c:240
(inlined by) change_p4d_range at mm/mprotect.c:260
change_protection+0x222/0x310
change_prot_numa+0x3e/0x60
task_numa_work+0x219/0x350
task_work_run+0xed/0x140
prepare_exit_to_usermode+0x2cc/0x2e0
ret_from_intr+0x32/0x42
Reported by Kernel Concurrency Sanitizer on:
CPU: 4 PID: 6364 Comm: mtest01 Tainted: G W L 5.5.0-next-20200210+ #5
Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
flush_tlb_batched_pending() is under PTL but the write is not, but
mm->tlb_flush_batched is only a bool type, so the value is unlikely to be
shattered. Thus, mark it as an intentional data race by using the data
race macro.
Link: http://lkml.kernel.org/r/1581450783-8262-1-git-send-email-cai@xxxxxx
Signed-off-by: Qian Cai <cai@xxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/rmap.c~mm-rmap-annotate-a-data-race-at-tlb_flush_batched
+++ a/mm/rmap.c
@@ -666,7 +666,7 @@ static bool should_defer_flush(struct mm
*/
void flush_tlb_batched_pending(struct mm_struct *mm)
{
- if (mm->tlb_flush_batched) {
+ if (data_race(mm->tlb_flush_batched)) {
flush_tlb_mm(mm);
/*
_
Patches currently in -mm which might be from cai@xxxxxx are
mm-swapfile-fix-and-annotate-various-data-races.patch
mm-memcontrol-fix-a-data-race-in-scan-count.patch
mm-list_lru-fix-a-data-race-in-list_lru_count_one.patch
mm-rmap-annotate-a-data-race-at-tlb_flush_batched.patch
mm-frontswap-mark-various-intentional-data-races.patch
mm-page_io-mark-various-intentional-data-races.patch
mm-swap_state-mark-various-intentional-data-races.patch
