syzbot

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BUG: KCSAN: data-race in d_invalidate / fast_dput

write to 0xffff888105f89490 of 8 bytes by task 4879 on cpu 1:
 __d_drop fs/dcache.c:576 [inline]
 d_invalidate+0x5b/0x200 fs/dcache.c:1691
 proc_invalidate_siblings_dcache+0x1c0/0x2a0 fs/proc/inode.c:142
 proc_sys_invalidate_dcache fs/proc/proc_sysctl.c:289 [inline]
 start_unregistering fs/proc/proc_sysctl.c:316 [inline]
 drop_sysctl_table+0xbd/0x270 fs/proc/proc_sysctl.c:1517
 drop_sysctl_table+0x1cb/0x270 fs/proc/proc_sysctl.c:1524
 unregister_sysctl_table+0x30/0x50 fs/proc/proc_sysctl.c:1542
 unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:177
 __devinet_sysctl_unregister net/ipv4/devinet.c:2700 [inline]
 devinet_sysctl_unregister net/ipv4/devinet.c:2728 [inline]
 inetdev_destroy net/ipv4/devinet.c:334 [inline]
 inetdev_event+0x6e4/0xba0 net/ipv4/devinet.c:1655
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info net/core/dev.c:2230 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 unregister_netdevice_many_notify+0xea0/0x16d0 net/core/dev.c:12381
 unregister_netdevice_many net/core/dev.c:12444 [inline]
 unregister_netdevice_queue net/core/dev.c:12258 [inline]
 unregister_netdevice include/linux/netdevice.h:3405 [inline]
 unregister_netdev+0x14c/0x1b0 net/core/dev.c:12462
 slip_close+0xe4/0x100 drivers/net/slip/slip.c:906
 tty_ldisc_close drivers/tty/tty_ldisc.c:455 [inline]
 tty_ldisc_kill+0x8d/0x140 drivers/tty/tty_ldisc.c:613
 tty_ldisc_release+0x171/0x1d0 drivers/tty/tty_ldisc.c:781
 tty_release_struct+0x1d/0xb0 drivers/tty/tty_io.c:1681
 tty_release+0x856/0xb10 drivers/tty/tty_io.c:1852
 __fput+0x29b/0x650 fs/file_table.c:468
 ____fput+0x1c/0x30 fs/file_table.c:496
 task_work_run+0x131/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x202/0x2a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105f89490 of 8 bytes by task 3045 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:366 [inline]
 retain_dentry fs/dcache.c:753 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:849
 dput+0x24/0x60 fs/dcache.c:924
 path_put fs/namei.c:665 [inline]
 terminate_walk+0x77/0x210 fs/namei.c:792
 path_openat+0x1e40/0x23b0 fs/namei.c:4788
 do_filp_open+0x109/0x230 fs/namei.c:4814
 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+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888237a4f478 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3045 Comm: dhcpcd 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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