syzbot

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BUG: KCSAN: data-race in dont_mount / lookup_fast

read-write to 0xffff888105704d80 of 4 bytes by task 5810 on cpu 0:
 dont_mount+0x27/0x40 include/linux/dcache.h:363
 vfs_unlink+0x288/0x3f0 fs/namei.c:4337
 do_unlinkat+0x236/0x4c0 fs/namei.c:4399
 __do_sys_unlink fs/namei.c:4447 [inline]
 __se_sys_unlink fs/namei.c:4445 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4445
 x64_sys_call+0x286b/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105704d80 of 4 bytes by task 2784 on cpu 1:
 d_revalidate fs/namei.c:860 [inline]
 lookup_fast+0xd9/0x2a0 fs/namei.c:1641
 walk_component+0x3f/0x230 fs/namei.c:2000
 lookup_last fs/namei.c:2461 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2485
 filename_lookup+0x127/0x300 fs/namei.c:2514
 user_path_at_empty+0x42/0x120 fs/namei.c:2921
 do_readlinkat+0x92/0x210 fs/stat.c:499
 __do_sys_readlink fs/stat.c:532 [inline]
 __se_sys_readlink fs/stat.c:529 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:529
 x64_sys_call+0x2613/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00600008 -> 0x00008008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2784 Comm: udevd Not tainted 6.9.0-rc5-syzkaller-00296-g5eb4573ea63d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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udevd[2784]: worker [5810] terminated by signal 33 (Unknown signal 33)
udevd[2784]: worker [5810] failed while handling '/devices/netdevsim4/net/eth2'
udevd[2784]: worker [5813] terminated by signal 33 (Unknown signal 33)
udevd[2784]: worker [5813] failed while handling '/devices/netdevsim4/net/eth1'