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authorQian Cai <cai@lca.pw>2020-08-14 17:31:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-14 19:56:57 -0700
commit9c1177b62a8c7f78fee5ede540825b844a1bf0c8 (patch)
treee0362a2e2c25aa1d67a5225de9bdf7de673fdcb4
parentabe1de4209f670ca81ba0d96f64fa9285c05a5ad (diff)
downloadlinux-stericsson-9c1177b62a8c7f78fee5ede540825b844a1bf0c8.tar.gz
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. Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Link: http://lkml.kernel.org/r/1581450783-8262-1-git-send-email-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/rmap.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 4ace1e32f705..83cc459edc40 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -672,7 +672,7 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
*/
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);
/*