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BUG: KCSAN: data-race in __follow_mount_rcu / __unlock_mount

read to 0xffff888105a4ce40 of 4 bytes by task 12655 on cpu 0:
 __follow_mount_rcu+0x156/0x2a0 fs/namei.c:1714
 handle_mounts fs/namei.c:1740 [inline]
 step_into_slowpath+0x30c/0x4c0 fs/namei.c:2104
 step_into fs/namei.c:2152 [inline]
 walk_component fs/namei.c:2288 [inline]
 link_path_walk+0x953/0xde0 fs/namei.c:-1
 path_openat+0x142/0x11c0 fs/namei.c:5006
 do_file_open+0x16c/0x290 fs/namei.c:5039
 do_sys_openat2+0xa1/0x140 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1459
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read-write to 0xffff888105a4ce40 of 4 bytes by task 12654 on cpu 1:
 maybe_free_mountpoint fs/namespace.c:979 [inline]
 unpin_mountpoint fs/namespace.c:994 [inline]
 __unlock_mount+0x142/0x1f0 fs/namespace.c:2905
 unlock_mount fs/namespace.c:2913 [inline]
 do_new_mount_fc fs/namespace.c:3933 [inline]
 do_new_mount+0x583/0x730 fs/namespace.c:3986
 path_mount+0x4ad/0xb90 fs/namespace.c:4337
 do_mount fs/namespace.c:4350 [inline]
 __do_sys_mount fs/namespace.c:4565 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4542
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4542
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12654 Comm: syz.1.2844 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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