syzbot ci has tested the following series [v4] kernfs: Add inotify IN_DELETE_SELF, IN_IGNORED support https://lore.kernel.org/all/[email protected] * [PATCH v4 1/3] kernfs: Don't set_nlink for directories being removed * [PATCH v4 2/3] kernfs: Send IN_DELETE_SELF and IN_IGNORED * [PATCH v4 3/3] selftests: memcg: Add tests for IN_DELETE_SELF and IN_IGNORED
and found the following issue: possible deadlock in __kernfs_remove Full report is available here: https://ci.syzbot.org/series/4b44d5c2-c2eb-4425-a19a-f9963b64f74f *** possible deadlock in __kernfs_remove tree: bpf-next URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git base: ba268514ea14b44570030e8ed2aef92a38679e85 arch: amd64 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 config: https://ci.syzbot.org/builds/45ab774f-e8d7-4def-8279-888a5cb2d01e/config syz repro: https://ci.syzbot.org/findings/b74cbc6a-1cef-4ae9-be46-dd9e8b29b648/syz_repro ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u8:1/13 is trying to acquire lock: ffff88816ef2b878 (kn->active#5){++++}-{0:0}, at: __kernfs_remove+0x47e/0x8c0 fs/kernfs/dir.c:1533 but task is already holding lock: ffff8881012e8ab8 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140 fs/kernfs/dir.c:1745 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&root->kernfs_supers_rwsem){++++}-{4:4}: down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537 kernfs_remove_by_name_ns+0x3f/0x140 fs/kernfs/dir.c:1745 acpi_unbind_one+0x2d8/0x3b0 drivers/acpi/glue.c:337 device_platform_notify_remove drivers/base/core.c:2386 [inline] device_del+0x547/0x8f0 drivers/base/core.c:3881 serdev_controller_add+0x46f/0x640 drivers/tty/serdev/core.c:785 serdev_tty_port_register+0x159/0x260 drivers/tty/serdev/serdev-ttyport.c:291 tty_port_register_device_attr_serdev+0xe7/0x170 drivers/tty/tty_port.c:187 serial_core_add_one_port drivers/tty/serial/serial_core.c:3107 [inline] serial_core_register_port+0x103a/0x28b0 drivers/tty/serial/serial_core.c:3305 serial8250_register_8250_port+0x1658/0x1fd0 drivers/tty/serial/8250/8250_core.c:822 serial_pnp_probe+0x568/0x7f0 drivers/tty/serial/8250/8250_pnp.c:480 pnp_device_probe+0x30b/0x4c0 drivers/pnp/driver.c:111 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x267/0xaf0 drivers/base/dd.c:661 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833 __driver_attach+0x3e7/0x710 drivers/base/dd.c:1227 bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383 bus_add_driver+0x345/0x670 drivers/base/bus.c:715 driver_register+0x23a/0x320 drivers/base/driver.c:249 serial8250_init+0x8f/0x160 drivers/tty/serial/8250/8250_platform.c:317 do_one_initcall+0x250/0x840 init/main.c:1378 do_initcall_level+0x104/0x190 init/main.c:1440 do_initcalls+0x59/0xa0 init/main.c:1456 kernel_init_freeable+0x2a6/0x3d0 init/main.c:1688 kernel_init+0x1d/0x1d0 init/main.c:1578 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #1 (&device->physical_node_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 acpi_get_first_physical_node drivers/acpi/bus.c:691 [inline] acpi_primary_dev_companion drivers/acpi/bus.c:710 [inline] acpi_companion_match+0x8a/0x120 drivers/acpi/bus.c:764 acpi_device_uevent_modalias+0x1a/0x30 drivers/acpi/device_sysfs.c:280 platform_uevent+0x3c/0xb0 drivers/base/platform.c:1411 dev_uevent+0x446/0x8a0 drivers/base/core.c:2692 kobject_uevent_env+0x477/0x9e0 lib/kobject_uevent.c:573 kobject_synth_uevent+0x585/0xbd0 lib/kobject_uevent.c:207 uevent_store+0x26/0x70 drivers/base/core.c:2773 kernfs_fop_write_iter+0x3af/0x540 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:686 ksys_write+0x150/0x270 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (kn->active#5){++++}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 kernfs_drain+0x27c/0x5f0 fs/kernfs/dir.c:511 __kernfs_remove+0x47e/0x8c0 fs/kernfs/dir.c:1533 kernfs_remove_by_name_ns+0xc0/0x140 fs/kernfs/dir.c:1751 sysfs_remove_file include/linux/sysfs.h:780 [inline] device_remove_file drivers/base/core.c:3071 [inline] device_del+0x506/0x8f0 drivers/base/core.c:3876 device_unregister+0x21/0xf0 drivers/base/core.c:3919 mac80211_hwsim_del_radio+0x2dc/0x490 drivers/net/wireless/virtual/mac80211_hwsim.c:5918 hwsim_exit_net+0xede/0xfa0 drivers/net/wireless/virtual/mac80211_hwsim.c:6807 ops_exit_list net/core/net_namespace.c:199 [inline] ops_undo_list+0x49f/0x940 net/core/net_namespace.c:252 cleanup_net+0x4df/0x7b0 net/core/net_namespace.c:696 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421 kthread+0x726/0x8b0 kernel/kthread.c:463 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 other info that might help us debug this: Chain exists of: kn->active#5 --> &device->physical_node_lock --> &root->kernfs_supers_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&root->kernfs_supers_rwsem); lock(&device->physical_node_lock); lock(&root->kernfs_supers_rwsem); lock(kn->active#5); *** DEADLOCK *** 4 locks held by kworker/u8:1/13: #0: ffff888100ef7948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff888100ef7948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340 #1: ffffc90000127bc0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc90000127bc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340 #2: ffffffff8f99d2d0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xfe/0x7b0 net/core/net_namespace.c:670 #3: ffff8881012e8ab8 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140 fs/kernfs/dir.c:1745 stack backtrace: CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Workqueue: netns cleanup_net Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 kernfs_drain+0x27c/0x5f0 fs/kernfs/dir.c:511 __kernfs_remove+0x47e/0x8c0 fs/kernfs/dir.c:1533 kernfs_remove_by_name_ns+0xc0/0x140 fs/kernfs/dir.c:1751 sysfs_remove_file include/linux/sysfs.h:780 [inline] device_remove_file drivers/base/core.c:3071 [inline] device_del+0x506/0x8f0 drivers/base/core.c:3876 device_unregister+0x21/0xf0 drivers/base/core.c:3919 mac80211_hwsim_del_radio+0x2dc/0x490 drivers/net/wireless/virtual/mac80211_hwsim.c:5918 hwsim_exit_net+0xede/0xfa0 drivers/net/wireless/virtual/mac80211_hwsim.c:6807 ops_exit_list net/core/net_namespace.c:199 [inline] ops_undo_list+0x49f/0x940 net/core/net_namespace.c:252 cleanup_net+0x4df/0x7b0 net/core/net_namespace.c:696 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421 kthread+0x726/0x8b0 kernel/kthread.c:463 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 </TASK> hsr_slave_0: left promiscuous mode hsr_slave_1: left promiscuous mode batman_adv: batadv0: Interface deactivated: batadv_slave_0 batman_adv: batadv0: Removing interface: batadv_slave_0 batman_adv: batadv0: Interface deactivated: batadv_slave_1 batman_adv: batadv0: Removing interface: batadv_slave_1 veth1_macvtap: left promiscuous mode veth0_macvtap: left promiscuous mode veth1_vlan: left promiscuous mode veth0_vlan: left promiscuous mode team0 (unregistering): Port device team_slave_1 removed team0 (unregistering): Port device team_slave_0 removed netdevsim netdevsim2 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0 *** If these findings have caused you to resend the series or submit a separate fix, please add the following tag to your commit message: Tested-by: [email protected] --- This report is generated by a bot. It may contain errors. syzbot ci engineers can be reached at [email protected].
