path: root/mm/swap_state.c
diff options
authorQian Cai <cai@lca.pw>2020-08-14 17:31:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-14 19:56:57 -0700
commitb96a3db2f37485e902794f28130f70dc834796a4 (patch)
tree21cd98ffe2b50d344b81efab339d8309d82a0970 /mm/swap_state.c
parent7b37e22675dfe8673083aaea84c9e7d6e436abbc (diff)
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')
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;