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BUG: KCSAN: data-race in fifo_open / wait_for_partner

read-write to 0xffff88811bbf836c of 4 bytes by task 3910 on cpu 0:
 fifo_open+0x86/0x5d0 fs/pipe.c:1132
 do_dentry_open+0x4ca/0xa90 fs/open.c:949
 vfs_open+0x37/0x1e0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x1b70/0x2050 fs/namei.c:4830
 do_file_open_root+0x233/0x430 fs/namei.c:4883
 file_open_root+0xfd/0x130 fs/open.c:1353
 file_open_handle fs/fhandle.c:412 [inline]
 do_handle_open+0x6b6/0x790 fs/fhandle.c:425
 __do_sys_open_by_handle_at fs/fhandle.c:448 [inline]
 __se_sys_open_by_handle_at fs/fhandle.c:439 [inline]
 __x64_sys_open_by_handle_at+0x44/0x50 fs/fhandle.c:439
 x64_sys_call+0x153d/0x3020 arch/x86/include/generated/asm/syscalls_64.h:305
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811bbf836c of 4 bytes by task 3911 on cpu 1:
 pipe_unlock fs/pipe.c:97 [inline]
 wait_for_partner+0xd5/0x1e0 fs/pipe.c:1106
 fifo_open+0x462/0x5d0 fs/pipe.c:1176
 do_dentry_open+0x4ca/0xa90 fs/open.c:949
 vfs_open+0x37/0x1e0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x1b70/0x2050 fs/namei.c:4830
 do_file_open+0x16c/0x290 fs/namei.c:4859
 do_sys_openat2+0x94/0x130 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1383
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3911 Comm: syz.4.161 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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