Commit b96a3db2 authored by Qian Cai's avatar Qian Cai Committed by Linus Torvalds
Browse files

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 ProLi...
parent 7b37e226
......@@ -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;
......
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