syzbot

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BUG: KCSAN: data-race in __do_page_fault / do_task_stat

read to 0xffff88811c5366d0 of 8 bytes by task 9366 on cpu 0:
 do_task_stat+0x4c7/0x1370 fs/proc/array.c:503
 proc_tgid_stat+0x3d/0x60 fs/proc/array.c:632
 proc_single_show+0x89/0xe0 fs/proc/base.c:756
 seq_read+0x350/0x960 fs/seq_file.c:229
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_loop_readv_writev fs/read_write.c:701 [inline]
 do_iter_read+0x357/0x3d0 fs/read_write.c:935
 vfs_readv+0x9c/0xf0 fs/read_write.c:997
 do_preadv+0x131/0x1d0 fs/read_write.c:1089
 __do_sys_preadv fs/read_write.c:1139 [inline]
 __se_sys_preadv fs/read_write.c:1134 [inline]
 __x64_sys_preadv+0x61/0x80 fs/read_write.c:1134
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88811c5366d0 of 8 bytes by task 9365 on cpu 1:
 do_user_addr_fault arch/x86/mm/fault.c:1481 [inline]
 __do_page_fault+0x6b1/0x9e0 arch/x86/mm/fault.c:1506
 do_page_fault+0x54/0x233 arch/x86/mm/fault.c:1530
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1202
 copy_user_enhanced_fast_string+0xe/0x30 arch/x86/lib/copy_user_64.S:204
 copy_page_to_iter_iovec lib/iov_iter.c:211 [inline]
 copy_page_to_iter+0x254/0x8b0 lib/iov_iter.c:900
 pipe_to_user+0x71/0xc0 fs/splice.c:1248
 splice_from_pipe_feed fs/splice.c:500 [inline]
 __splice_from_pipe+0x248/0x480 fs/splice.c:624
 vmsplice_to_user fs/splice.c:1272 [inline]
 do_vmsplice.part.0+0x1c5/0x210 fs/splice.c:1350
 do_vmsplice fs/splice.c:1344 [inline]
 __do_sys_vmsplice+0x15f/0x1c0 fs/splice.c:1371
 __se_sys_vmsplice fs/splice.c:1353 [inline]
 __x64_sys_vmsplice+0x5e/0x80 fs/splice.c:1353
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9365 Comm: syz-executor.1 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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