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| author |   Qian Cai <cai@lca.pw> | 2020-08-14 17:31:24 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-14 19:56:57 -0700 |
| commit | b96a3db2f37485e902794f28130f70dc834796a4 (patch) | |
| tree | 21cd98ffe2b50d344b81efab339d8309d82a0970 /mm/swap_state.c | |
| parent | mm/page_io: mark various intentional data races (diff) | |
| download | linux-dev-b96a3db2f37485e902794f28130f70dc834796a4.tar.xz linux-dev-b96a3db2f37485e902794f28130f70dc834796a4.zip | |
mm/swap_state: mark various intentional data races
swap_cache_info.* could be accessed concurrently as noticed by
KCSAN,
BUG: KCSAN: data-race in lookup_swap_cache / lookup_swap_cache
write to 0xffffffff85517318 of 8 bytes by task 94138 on cpu 101:
lookup_swap_cache+0x12e/0x460
lookup_swap_cache at mm/swap_state.c:322
do_swap_page+0x112/0xeb0
__handle_mm_fault+0xc7a/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
read to 0xffffffff85517318 of 8 bytes by task 91655 on cpu 100:
lookup_swap_cache+0x117/0x460
lookup_swap_cache at mm/swap_state.c:322
shmem_swapin_page+0xc7/0x9e0
shmem_getpage_gfp+0x2ca/0x16c0
shmem_fault+0xef/0x3c0
__do_fault+0x9e/0x220
do_fault+0x4a0/0x920
__handle_mm_fault+0xc69/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
Reported by Kernel Concurrency Sanitizer on:
CPU: 100 PID: 91655 Comm: systemd-journal Tainted: G W O L 5.5.0-next-20200204+ #6
Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
write to 0xffffffff8d717308 of 8 bytes by task 11365 on cpu 87:
__delete_from_swap_cache+0x681/0x8b0
__delete_from_swap_cache at mm/swap_state.c:178
read to 0xffffffff8d717308 of 8 bytes by task 11275 on cpu 53:
__delete_from_swap_cache+0x66e/0x8b0
__delete_from_swap_cache at mm/swap_state.c:178
Both the read and write are done as lockless. Since swap_cache_info.*
are only used to print out counter information, even if any of them
missed a few incremental due to data races, it will be harmless, so just
mark it as an intentional data race using the data_race() macro.
While at it, fix a checkpatch.pl warning,
WARNING: Single statement macros should not use a do {} while (0) loop
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/20200207003715.1578-1-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swap_state.c')
| -rw-r--r-- | mm/swap_state.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/swap_state.c b/mm/swap_state.c index d9d4a49f3241..c16eebb81d8b 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -57,8 +57,8 @@ static bool enable_vma_readahead __read_mostly = true; #define GET_SWAP_RA_VAL(vma) \ (atomic_long_read(&(vma)->swap_readahead_info) ? : 4) -#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0) -#define ADD_CACHE_INFO(x, nr) do { swap_cache_info.x += (nr); } while (0) +#define INC_CACHE_INFO(x) data_race(swap_cache_info.x++) +#define ADD_CACHE_INFO(x, nr) data_race(swap_cache_info.x += (nr)) static struct { unsigned long add_total; |