syzbot

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BUG: KCSAN: data-race in __fsnotify_parent / d_make_discardable

write to 0xffff888107a5e840 of 4 bytes by task 3504 on cpu 0:
 d_make_discardable+0x4f/0xa0 fs/dcache.c:936
 simple_unlink+0x68/0x80 fs/libfs.c:807
 shmem_unlink+0x12d/0x140 mm/shmem.c:3991
 shmem_rename2+0x18e/0x310 mm/shmem.c:4072
 vfs_rename+0x97f/0xad0 fs/namei.c:5938
 do_renameat2+0x383/0x810 fs/namei.c:6056
 __do_sys_rename fs/namei.c:6099 [inline]
 __se_sys_rename fs/namei.c:6097 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:6097
 x64_sys_call+0x24e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107a5e840 of 4 bytes by task 3004 on cpu 1:
 __fsnotify_parent+0xbc/0x3a0 fs/notify/fsnotify.c:245
 fsnotify_parent include/linux/fsnotify.h:96 [inline]
 fsnotify_path include/linux/fsnotify.h:113 [inline]
 fsnotify_file include/linux/fsnotify.h:127 [inline]
 fsnotify_open include/linux/fsnotify.h:446 [inline]
 vfs_open+0x19c/0x1e0 fs/open.c:1101
 do_open fs/namei.c:4637 [inline]
 path_openat+0x1ddd/0x23b0 fs/namei.c:4796
 do_filp_open+0x109/0x230 fs/namei.c:4823
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1447
 x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x08200080 -> 0x00200180

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3004 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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