syzbot

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BUG: KCSAN: data-race in fifo_open / pipe_lock

write to 0xffff888134bc836c of 4 bytes by task 17760 on cpu 1:
 fifo_open+0xab/0x6a0 fs/pipe.c:1086
 do_dentry_open+0x53e/0x830 fs/open.c:826
 vfs_open+0x43/0x50 fs/open.c:940
 do_open fs/namei.c:3361 [inline]
 path_openat+0x184e/0x20b0 fs/namei.c:3494
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_open fs/open.c:1211 [inline]
 __se_sys_open fs/open.c:1207 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1207
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888134bc836c of 4 bytes by task 17738 on cpu 0:
 pipe_lock_nested fs/pipe.c:65 [inline]
 pipe_lock+0x13/0x40 fs/pipe.c:74
 iter_file_splice_write+0xda/0x750 fs/splice.c:635
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0x9aa/0xd30 fs/splice.c:1079
 __do_splice fs/splice.c:1144 [inline]
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice+0x2a6/0x390 fs/splice.c:1332
 __x64_sys_splice+0x74/0x80 fs/splice.c:1332
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17738 Comm: syz-executor.5 Not tainted 5.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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