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BUG: KCSAN: data-race in handle_mm_fault / watchdog

read to 0xffff8881227140d0 of 8 bytes by task 949 on cpu 1:
 check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
 watchdog+0x2b1/0x960 kernel/hung_task.c:289
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff8881227140d0 of 8 bytes by task 7867 on cpu 0:
 handle_mm_fault+0x4a/0x530 mm/memory.c:4089
 do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
 __do_page_fault+0x456/0x8d0 arch/x86/mm/fault.c:1506
 do_page_fault+0x38/0x194 arch/x86/mm/fault.c:1530
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203
 copy_user_generic_unrolled+0x89/0xc0 arch/x86/lib/copy_user_64.S:90
 copy_page_to_iter_iovec lib/iov_iter.c:211 [inline]
 copy_page_to_iter+0x252/0x8d0 lib/iov_iter.c:920
 shmem_file_read_iter+0x333/0x720 mm/shmem.c:2615
 call_read_iter include/linux/fs.h:1896 [inline]
 new_sync_read+0x389/0x4f0 fs/read_write.c:414
 __vfs_read+0xb1/0xc0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7867 Comm: udevd Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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