syzbot

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BUG: KCSAN: data-race in fast_dput / shrink_dentry_list

write to 0xffff888106e27cc0 of 4 bytes by task 14098 on cpu 1:
 shrink_dentry_list+0x127/0x340 fs/dcache.c:423
 shrink_dcache_sb+0x188/0x2d0 fs/dcache.c:1296
 reconfigure_super+0x2aa/0x4f0 fs/super.c:889
 do_remount fs/namespace.c:2639 [inline]
 path_mount+0x1442/0x1ce0 fs/namespace.c:3227
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888106e27cc0 of 4 bytes by task 14099 on cpu 0:
 fast_dput+0x14/0x1c0 fs/dcache.c:749
 dput+0x26/0x360 fs/dcache.c:875
 path_put+0x1b/0x30 fs/namei.c:546
 do_mount fs/namespace.c:3249 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x247/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00290440 -> 0x00210040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14099 Comm: syz-executor.1 Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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