Hello, I found a potential bug titled " possible deadlock in kernfs_unlink_sibling " with modified syzkaller in the Linux6.12.24(longterm maintenance, last updated on April 20, 2025). (The latest version of 6.12 is 6.12-25 at present. However, after comparison, I found that there seems to be no fix for this bug in the latest version.) Unfortunately, I am unable to reproduce this bug. If you fix this issue, please add the following tag to the commit: Reported-by: Jianzhou Zhao luckd0g@163.com, xingwei lee xrivendell7@gmail.com,Penglei Jiang superman.xpt@gmail.com The commit of the kernel is : b6efa8ce222e58cfe2bbaa4e3329818c2b4bd74e kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=55f8591b98dd132 compiler: gcc version 11.4.0

------------[ cut here ]----------------------------------------- TITLE: possible deadlock in kernfs_unlink_sibling ------------[ cut here ]------------ ====================================================== ====================================================== WARNING: possible circular locking dependency detected 6.12.24 #3 Not tainted ------------------------------------------------------ syz-executor/42274 is trying to acquire lock: ffff88801bae51e0 (&root->kernfs_iattr_rwsem){++++}-{3:3}, at: kernfs_unlink_sibling+0xad/0x2c0 fs/kernfs/dir.c:413

but task is already holding lock: ffff88801bae5148 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove_by_name_ns+0x89/0x130 fs/kernfs/dir.c:1689

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #13 (&root->kernfs_rwsem){++++}-{3:3}: down_write+0x92/0x200 kernel/locking/rwsem.c:1577 kernfs_add_one+0xac/0x530 fs/kernfs/dir.c:778 kernfs_create_dir_ns+0xfa/0x160 fs/kernfs/dir.c:1071 internal_create_group+0x338/0xeb0 fs/sysfs/group.c:167 cpuhp_invoke_callback+0x3d2/0x9d0 kernel/cpu.c:194 cpuhp_issue_call+0x1c1/0x8d0 kernel/cpu.c:2370 __cpuhp_setup_state_cpuslocked+0x400/0x700 kernel/cpu.c:2516 __cpuhp_setup_state+0x106/0x320 kernel/cpu.c:2545 do_one_initcall+0x10e/0x6d0 init/main.c:1269 do_initcall_level init/main.c:1331 [inline] do_initcalls init/main.c:1347 [inline] do_basic_setup init/main.c:1366 [inline] kernel_init_freeable+0x5ae/0x8a0 init/main.c:1580 kernel_init+0x1e/0x2d0 init/main.c:1469 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #12 (cpuhp_state_mutex){+.+.}-{3:3}:

-> #11 (cpu_hotplug_lock){++++}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x42/0x160 kernel/cpu.c:490 __static_call_update+0x8b/0x630 kernel/static_call_inline.c:139 tracepoint_update_call kernel/tracepoint.c:317 [inline] tracepoint_add_func+0xa18/0xe50 kernel/tracepoint.c:358 tracepoint_probe_register_prio kernel/tracepoint.c:511 [inline] tracepoint_probe_register+0xa5/0xf0 kernel/tracepoint.c:531 register_trace_sched_wakeup include/trace/events/sched.h:178 [inline] tracing_sched_register kernel/trace/trace_sched_switch.c:56 [inline] tracing_start_sched_switch+0x97/0x1e0 kernel/trace/trace_sched_switch.c:110 __ftrace_event_enable_disable+0x68b/0x8a0 kernel/trace/trace_events.c:831 ftrace_event_enable_disable kernel/trace/trace_events.c:871 [inline] __ftrace_set_clr_event_nolock+0x29b/0x390 kernel/trace/trace_events.c:1200 __ftrace_set_clr_event kernel/trace/trace_events.c:1222 [inline] trace_set_clr_event+0xec/0x150 kernel/trace/trace_events.c:1287 __set_printk_clr_event kernel/trace/bpf_trace.c:416 [inline] bpf_get_trace_printk_proto+0x22/0x90 kernel/trace/bpf_trace.c:422 bpf_base_func_proto+0x9d6/0xbb0 kernel/bpf/helpers.c:2024 bpf_sk_base_func_proto+0x167/0x190 net/core/filter.c:11925 tc_cls_act_func_proto+0x506/0x510 net/core/filter.c:8289 get_helper_proto kernel/bpf/verifier.c:10430 [inline] mark_fastcall_pattern_for_call+0x242/0xd50 kernel/bpf/verifier.c:16305 mark_fastcall_patterns kernel/bpf/verifier.c:16416 [inline] bpf_check+0x85e6/0xb370 kernel/bpf/verifier.c:22458 bpf_prog_load+0x14d9/0x25d0 kernel/bpf/syscall.c:2847 __sys_bpf+0x1711/0x4f20 kernel/bpf/syscall.c:5667 __do_sys_bpf kernel/bpf/syscall.c:5774 [inline] __se_sys_bpf kernel/bpf/syscall.c:5772 [inline] __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5772 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #10 (tracepoints_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 tracepoint_probe_register_prio kernel/tracepoint.c:507 [inline] tracepoint_probe_register+0x7c/0xf0 kernel/tracepoint.c:531 register_trace_block_rq_insert include/trace/events/block.h:238 [inline] blk_register_tracepoints+0x1b/0x3c0 kernel/trace/blktrace.c:1094 get_probe_ref kernel/trace/blktrace.c:337 [inline] do_blk_trace_setup+0x98a/0xbc0 kernel/trace/blktrace.c:611 __blk_trace_setup+0xca/0x180 kernel/trace/blktrace.c:630 blk_trace_setup+0x47/0x70 kernel/trace/blktrace.c:648 sg_ioctl_common drivers/scsi/sg.c:1114 [inline] sg_ioctl+0x65e/0x2720 drivers/scsi/sg.c:1156 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #9 (blk_probe_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 get_probe_ref kernel/trace/blktrace.c:335 [inline] do_blk_trace_setup+0x797/0xbc0 kernel/trace/blktrace.c:611 __blk_trace_setup+0xca/0x180 kernel/trace/blktrace.c:630 blk_trace_setup+0x47/0x70 kernel/trace/blktrace.c:648 sg_ioctl_common drivers/scsi/sg.c:1114 [inline] sg_ioctl+0x65e/0x2720 drivers/scsi/sg.c:1156 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #8 (&q->debugfs_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 blk_mq_init_sched+0x436/0x650 block/blk-mq-sched.c:473 elevator_init_mq+0x2cc/0x420 block/elevator.c:610 device_add_disk+0x10e/0x12f0 block/genhd.c:411 sd_probe+0xa0e/0xf80 drivers/scsi/sd.c:4024 call_driver_probe drivers/base/dd.c:579 [inline] really_probe+0x24f/0xa90 drivers/base/dd.c:658 __driver_probe_device+0x1df/0x450 drivers/base/dd.c:800 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:830 __device_attach_driver+0x1db/0x2f0 drivers/base/dd.c:958 bus_for_each_drv+0x149/0x1d0 drivers/base/bus.c:459 __device_attach_async_helper+0x1d1/0x290 drivers/base/dd.c:987 async_run_entry_fn+0x9c/0x530 kernel/async.c:129 process_one_work+0xa02/0x1bf0 kernel/workqueue.c:3232 process_scheduled_works kernel/workqueue.c:3314 [inline] worker_thread+0x677/0xe90 kernel/workqueue.c:3395 kthread+0x2c7/0x3b0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #7 (&q->q_usage_counter(queue)#51){++++}-{0:0}: blk_queue_enter+0x4d0/0x600 block/blk-core.c:328 blk_mq_alloc_request+0x422/0x9c0 block/blk-mq.c:680 scsi_alloc_request drivers/scsi/scsi_lib.c:1227 [inline] scsi_execute_cmd+0x1fe/0xf20 drivers/scsi/scsi_lib.c:304 read_capacity_16+0x1f2/0xe60 drivers/scsi/sd.c:2655 sd_read_capacity drivers/scsi/sd.c:2824 [inline] sd_revalidate_disk.isra.0+0x1989/0xa440 drivers/scsi/sd.c:3734 sd_probe+0x887/0xf80 drivers/scsi/sd.c:4010 call_driver_probe drivers/base/dd.c:579 [inline] really_probe+0x24f/0xa90 drivers/base/dd.c:658 __driver_probe_device+0x1df/0x450 drivers/base/dd.c:800 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:830 __device_attach_driver+0x1db/0x2f0 drivers/base/dd.c:958 bus_for_each_drv+0x149/0x1d0 drivers/base/bus.c:459 __device_attach_async_helper+0x1d1/0x290 drivers/base/dd.c:987 async_run_entry_fn+0x9c/0x530 kernel/async.c:129 process_one_work+0xa02/0x1bf0 kernel/workqueue.c:3232 process_scheduled_works kernel/workqueue.c:3314 [inline] worker_thread+0x677/0xe90 kernel/workqueue.c:3395 kthread+0x2c7/0x3b0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #6 (&q->limits_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 queue_limits_start_update include/linux/blkdev.h:935 [inline] loop_reconfigure_limits+0x1f2/0x960 drivers/block/loop.c:1004 loop_set_block_size drivers/block/loop.c:1474 [inline] lo_simple_ioctl drivers/block/loop.c:1497 [inline] lo_ioctl+0xb92/0x1870 drivers/block/loop.c:1560 blkdev_ioctl+0x27b/0x6c0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&q->q_usage_counter(io)#19){++++}-{0:0}: bio_queue_enter block/blk.h:76 [inline] blk_mq_submit_bio+0x2167/0x2b70 block/blk-mq.c:3090 __submit_bio+0x399/0x630 block/blk-core.c:629 __submit_bio_noacct_mq block/blk-core.c:716 [inline] submit_bio_noacct_nocheck+0x6c3/0xd00 block/blk-core.c:745 submit_bio_noacct+0x57a/0x1fa0 block/blk-core.c:868 nilfs_btnode_submit_block+0x58a/0x6e0 fs/nilfs2/btnode.c:139 __nilfs_btree_get_block+0x10b/0x6b0 fs/nilfs2/btree.c:481 nilfs_btree_do_lookup+0x3ea/0x8e0 fs/nilfs2/btree.c:579 nilfs_btree_lookup+0x4b/0x110 fs/nilfs2/btree.c:696 nilfs_bmap_lookup_at_level+0xd4/0x460 fs/nilfs2/bmap.c:69 nilfs_bmap_lookup fs/nilfs2/bmap.h:182 [inline] nilfs_mdt_submit_block+0x1a1/0x870 fs/nilfs2/mdt.c:141 nilfs_mdt_read_block+0x92/0x3c0 fs/nilfs2/mdt.c:175 nilfs_mdt_get_block+0xd2/0xa40 fs/nilfs2/mdt.c:250 nilfs_palloc_get_block+0xc0/0x310 fs/nilfs2/alloc.c:217 nilfs_palloc_get_entry_block+0x16b/0x1d0 fs/nilfs2/alloc.c:319 nilfs_dat_translate+0x82/0x3b0 fs/nilfs2/dat.c:413 nilfs_bmap_lookup_at_level+0x250/0x460 fs/nilfs2/bmap.c:74 nilfs_bmap_lookup fs/nilfs2/bmap.h:182 [inline] nilfs_mdt_submit_block+0x1a1/0x870 fs/nilfs2/mdt.c:141 nilfs_mdt_read_block+0x92/0x3c0 fs/nilfs2/mdt.c:175 nilfs_mdt_get_block+0xd2/0xa40 fs/nilfs2/mdt.c:250 nilfs_sufile_read+0x20f/0x5f0 fs/nilfs2/sufile.c:1254 nilfs_load_super_root fs/nilfs2/the_nilfs.c:128 [inline] load_nilfs+0x69d/0x1300 fs/nilfs2/the_nilfs.c:299 nilfs_fill_super fs/nilfs2/super.c:1067 [inline] nilfs_get_tree+0xa62/0x10d0 fs/nilfs2/super.c:1220 vfs_get_tree+0x94/0x380 fs/super.c:1814 do_new_mount fs/namespace.c:3512 [inline] path_mount+0x6b2/0x1ea0 fs/namespace.c:3839 do_mount fs/namespace.c:3852 [inline] __do_sys_mount fs/namespace.c:4062 [inline] __se_sys_mount fs/namespace.c:4039 [inline] __x64_sys_mount+0x284/0x310 fs/namespace.c:4039 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&nilfs_bmap_dat_lock_key){++++}-{3:3}: down_read+0x9a/0x330 kernel/locking/rwsem.c:1524 nilfs_bmap_lookup_at_level+0x7f/0x460 fs/nilfs2/bmap.c:68 nilfs_bmap_lookup fs/nilfs2/bmap.h:182 [inline] nilfs_mdt_submit_block+0x1a1/0x870 fs/nilfs2/mdt.c:141 nilfs_mdt_read_block+0x92/0x3c0 fs/nilfs2/mdt.c:175 nilfs_mdt_get_block+0xd2/0xa40 fs/nilfs2/mdt.c:250 nilfs_palloc_get_block+0xc0/0x310 fs/nilfs2/alloc.c:217 nilfs_palloc_get_entry_block+0x16b/0x1d0 fs/nilfs2/alloc.c:319 nilfs_dat_translate+0x82/0x3b0 fs/nilfs2/dat.c:413 nilfs_direct_lookup_contig+0x294/0x330 fs/nilfs2/direct.c:67 nilfs_bmap_lookup_contig+0x89/0x190 fs/nilfs2/bmap.c:100 nilfs_get_block+0x1fc/0xa70 fs/nilfs2/inode.c:82 do_mpage_readpage+0x6e2/0x16a0 fs/mpage.c:225 mpage_readahead+0x344/0x580 fs/mpage.c:374 read_pages+0x19b/0xd50 mm/readahead.c:160 page_cache_ra_unbounded+0x3ac/0x680 mm/readahead.c:290 do_page_cache_ra mm/readahead.c:320 [inline] page_cache_ra_order+0x8ee/0xb70 mm/readahead.c:519 page_cache_sync_ra+0x4e3/0x9e0 mm/readahead.c:607 page_cache_sync_readahead include/linux/pagemap.h:1394 [inline] filemap_get_pages+0x327/0x19f0 mm/filemap.c:2558 filemap_read+0x3a2/0xc70 mm/filemap.c:2656 generic_file_read_iter+0x349/0x450 mm/filemap.c:2844 __kernel_read+0x3c6/0xb20 fs/read_write.c:527 integrity_kernel_read+0x7f/0xb0 security/integrity/iint.c:28 ima_calc_file_hash_tfm+0x2bd/0x3c0 security/integrity/ima/ima_crypto.c:480 ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline] ima_calc_file_hash+0x1b5/0x490 security/integrity/ima/ima_crypto.c:568 ima_collect_measurement+0x86c/0xa20 security/integrity/ima/ima_api.c:293 process_measurement+0xff9/0x1fb0 security/integrity/ima/ima_main.c:383 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:583 security_file_post_open+0x95/0x230 security/security.c:3129 do_open fs/namei.c:3776 [inline] path_openat+0x14d8/0x2960 fs/namei.c:3933 do_filp_open+0x1c7/0x410 fs/namei.c:3960 do_sys_openat2+0x164/0x1d0 fs/open.c:1415 do_sys_open fs/open.c:1430 [inline] __do_sys_openat fs/open.c:1446 [inline] __se_sys_openat fs/open.c:1441 [inline] __x64_sys_openat+0x140/0x1f0 fs/open.c:1441 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&bmap->b_sem){++++}-{3:3}: down_write+0x92/0x200 kernel/locking/rwsem.c:1577 nilfs_bmap_clear+0x1c/0xa0 fs/nilfs2/bmap.c:319 nilfs_clear_inode+0x21c/0x330 fs/nilfs2/inode.c:869 nilfs_evict_inode+0x3c1/0x530 fs/nilfs2/inode.c:889 evict+0x3ef/0x940 fs/inode.c:725 dispose_list+0x117/0x1e0 fs/inode.c:774 prune_icache_sb+0xeb/0x150 fs/inode.c:963 super_cache_scan+0x37f/0x570 fs/super.c:223 do_shrink_slab+0x44b/0x1190 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0xb61/0x12a0 mm/shrinker.c:628 shrink_one+0x4ad/0x7c0 mm/vmscan.c:4835 shrink_many mm/vmscan.c:4896 [inline] lru_gen_shrink_node mm/vmscan.c:4974 [inline] shrink_node+0x2420/0x3890 mm/vmscan.c:5954 kswapd_shrink_node mm/vmscan.c:6782 [inline] balance_pgdat+0xbe5/0x18c0 mm/vmscan.c:6974 kswapd+0x702/0xd50 mm/vmscan.c:7243 kthread+0x2c7/0x3b0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #2 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:3853 [inline] fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:3867 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4058 [inline] slab_alloc_node mm/slub.c:4136 [inline] kmem_cache_alloc_noprof+0x4e/0x2f0 mm/slub.c:4163 __kernfs_iattrs+0xbc/0x3f0 fs/kernfs/inode.c:37 kernfs_iattrs fs/kernfs/inode.c:60 [inline] kernfs_xattr_set fs/kernfs/inode.c:309 [inline] kernfs_vfs_xattr_set+0x5d/0xe0 fs/kernfs/inode.c:340 __vfs_setxattr+0x173/0x1e0 fs/xattr.c:200 __vfs_setxattr_noperm+0x129/0x670 fs/xattr.c:234 __vfs_setxattr_locked+0x1d7/0x260 fs/xattr.c:295 vfs_setxattr+0x143/0x360 fs/xattr.c:321 do_setxattr+0x171/0x1e0 fs/xattr.c:629 path_setxattr+0x202/0x260 fs/xattr.c:658 __do_sys_setxattr fs/xattr.c:676 [inline] __se_sys_setxattr fs/xattr.c:672 [inline] __x64_sys_setxattr+0xc4/0x160 fs/xattr.c:672 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (iattr_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 __kernfs_iattrs+0x2b/0x3f0 fs/kernfs/inode.c:32 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr+0x4d/0x3d0 fs/kernfs/inode.c:73 kernfs_iop_setattr+0x12b/0x190 fs/kernfs/inode.c:127 notify_change+0x6d3/0x1280 fs/attr.c:503 do_truncate+0x143/0x200 fs/open.c:65 handle_truncate fs/namei.c:3395 [inline] do_open fs/namei.c:3778 [inline] path_openat+0x22b6/0x2960 fs/namei.c:3933 do_filp_open+0x1c7/0x410 fs/namei.c:3960 do_sys_openat2+0x164/0x1d0 fs/open.c:1415 do_sys_open fs/open.c:1430 [inline] __do_sys_openat fs/open.c:1446 [inline] __se_sys_openat fs/open.c:1441 [inline] __x64_sys_openat+0x140/0x1f0 fs/open.c:1441 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&root->kernfs_iattr_rwsem){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x2425/0x3b90 kernel/locking/lockdep.c:5202 lock_acquire.part.0+0x11b/0x370 kernel/locking/lockdep.c:5825 down_write+0x92/0x200 kernel/locking/rwsem.c:1577 kernfs_unlink_sibling+0xad/0x2c0 fs/kernfs/dir.c:413 __kernfs_remove+0x2b3/0x670 fs/kernfs/dir.c:1492 kernfs_remove_by_name_ns+0xb4/0x130 fs/kernfs/dir.c:1694 kernfs_remove_by_name include/linux/kernfs.h:625 [inline] remove_files+0x96/0x1c0 fs/sysfs/group.c:28 sysfs_remove_group+0x8b/0x180 fs/sysfs/group.c:319 sysfs_remove_groups fs/sysfs/group.c:343 [inline] sysfs_remove_groups+0x60/0xa0 fs/sysfs/group.c:335 __kobject_del+0x89/0x1f0 lib/kobject.c:595 kobject_cleanup lib/kobject.c:680 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2e5/0x4c0 lib/kobject.c:737 net_rx_queue_update_kobjects+0x4d4/0x640 net/core/net-sysfs.c:1178 remove_queue_kobjects net/core/net-sysfs.c:1953 [inline] netdev_unregister_kobject+0x150/0x270 net/core/net-sysfs.c:2107 unregister_netdevice_many_notify+0x1202/0x1ce0 net/core/dev.c:11503 unregister_netdevice_many net/core/dev.c:11531 [inline] unregister_netdevice_queue+0x307/0x3f0 net/core/dev.c:11405 unregister_netdevice include/linux/netdevice.h:3126 [inline] nsim_destroy+0x102/0x6c0 drivers/net/netdevsim/netdev.c:778 __nsim_dev_port_del+0x189/0x240 drivers/net/netdevsim/dev.c:1428 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline] nsim_dev_reload_destroy+0x105/0x490 drivers/net/netdevsim/dev.c:1661 nsim_drv_remove+0x52/0x1d0 drivers/net/netdevsim/dev.c:1676 device_remove+0xc8/0x170 drivers/base/dd.c:567 __device_release_driver drivers/base/dd.c:1273 [inline] device_release_driver_internal+0x443/0x620 drivers/base/dd.c:1296 bus_remove_device+0x22f/0x420 drivers/base/bus.c:576 device_del+0x395/0x9d0 drivers/base/core.c:3855 device_unregister+0x1e/0xc0 drivers/base/core.c:3896 nsim_bus_dev_del drivers/net/netdevsim/bus.c:462 [inline] del_device_store+0x34e/0x4b0 drivers/net/netdevsim/bus.c:226 bus_attr_store+0x71/0xb0 drivers/base/bus.c:172 sysfs_kf_write+0x114/0x170 fs/sysfs/file.c:136 kernfs_fop_write_iter+0x335/0x500 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:590 [inline] vfs_write+0xbfc/0x10d0 fs/read_write.c:683 ksys_write+0x122/0x250 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of: &root->kernfs_iattr_rwsem --> cpuhp_state_mutex --> &root->kernfs_rwsem

Possible unsafe locking scenario:

CPU0 CPU1 ---- ---- lock(&root->kernfs_rwsem); lock(cpuhp_state_mutex); lock(&root->kernfs_rwsem); lock(&root->kernfs_iattr_rwsem);

*** DEADLOCK ***

8 locks held by syz-executor/42274: #0: ffff8880454fe420 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x122/0x250 fs/read_write.c:736 #1: ffff88806a42d488 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x27a/0x500 fs/kernfs/file.c:325 #2: ffff888043faf0f8 (kn->active#64){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x29e/0x500 fs/kernfs/file.c:326 #3: ffffffff8f280da8 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: del_device_store+0xc9/0x4b0 drivers/net/netdevsim/bus.c:216 #4: ffff88801fc9c0e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline] #4: ffff88801fc9c0e8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline] #4: ffff88801fc9c0e8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x620 drivers/base/dd.c:1293 #5: ffff88801fc9d250 (&devlink->lock_key#42){+.+.}-{3:3}, at: nsim_drv_remove+0x4a/0x1d0 drivers/net/netdevsim/dev.c:1675 #6: ffffffff8fce93a8 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x6b/0x6c0 drivers/net/netdevsim/netdev.c:773 #7: ffff88801bae5148 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove_by_name_ns+0x89/0x130 fs/kernfs/dir.c:1689

stack backtrace: CPU: 1 UID: 0 PID: 42274 Comm: syz-executor Not tainted 6.12.24 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120 print_circular_bug+0x406/0x5c0 kernel/locking/lockdep.c:2074 check_noncircular+0x2f7/0x3e0 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x2425/0x3b90 kernel/locking/lockdep.c:5202 lock_acquire.part.0+0x11b/0x370 kernel/locking/lockdep.c:5825 down_write+0x92/0x200 kernel/locking/rwsem.c:1577 kernfs_unlink_sibling+0xad/0x2c0 fs/kernfs/dir.c:413 __kernfs_remove+0x2b3/0x670 fs/kernfs/dir.c:1492 kernfs_remove_by_name_ns+0xb4/0x130 fs/kernfs/dir.c:1694 kernfs_remove_by_name include/linux/kernfs.h:625 [inline] remove_files+0x96/0x1c0 fs/sysfs/group.c:28 sysfs_remove_group+0x8b/0x180 fs/sysfs/group.c:319 sysfs_remove_groups fs/sysfs/group.c:343 [inline] sysfs_remove_groups+0x60/0xa0 fs/sysfs/group.c:335 __kobject_del+0x89/0x1f0 lib/kobject.c:595 kobject_cleanup lib/kobject.c:680 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2e5/0x4c0 lib/kobject.c:737 net_rx_queue_update_kobjects+0x4d4/0x640 net/core/net-sysfs.c:1178 remove_queue_kobjects net/core/net-sysfs.c:1953 [inline] netdev_unregister_kobject+0x150/0x270 net/core/net-sysfs.c:2107 unregister_netdevice_many_notify+0x1202/0x1ce0 net/core/dev.c:11503 unregister_netdevice_many net/core/dev.c:11531 [inline] unregister_netdevice_queue+0x307/0x3f0 net/core/dev.c:11405 unregister_netdevice include/linux/netdevice.h:3126 [inline] nsim_destroy+0x102/0x6c0 drivers/net/netdevsim/netdev.c:778 __nsim_dev_port_del+0x189/0x240 drivers/net/netdevsim/dev.c:1428 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline] nsim_dev_reload_destroy+0x105/0x490 drivers/net/netdevsim/dev.c:1661 nsim_drv_remove+0x52/0x1d0 drivers/net/netdevsim/dev.c:1676 device_remove+0xc8/0x170 drivers/base/dd.c:567 __device_release_driver drivers/base/dd.c:1273 [inline] device_release_driver_internal+0x443/0x620 drivers/base/dd.c:1296 bus_remove_device+0x22f/0x420 drivers/base/bus.c:576 device_del+0x395/0x9d0 drivers/base/core.c:3855 device_unregister+0x1e/0xc0 drivers/base/core.c:3896 nsim_bus_dev_del drivers/net/netdevsim/bus.c:462 [inline] del_device_store+0x34e/0x4b0 drivers/net/netdevsim/bus.c:226 bus_attr_store+0x71/0xb0 drivers/base/bus.c:172 sysfs_kf_write+0x114/0x170 fs/sysfs/file.c:136 kernfs_fop_write_iter+0x335/0x500 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:590 [inline] vfs_write+0xbfc/0x10d0 fs/read_write.c:683 ksys_write+0x122/0x250 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7feb2b1ac01f Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 79 0d 03 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 bc 0d 03 00 48 RSP: 002b:00007ffdd4ed8e70 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007feb2b1ac01f RDX: 0000000000000001 RSI: 00007ffdd4ed8ec0 RDI: 0000000000000005 RBP: 0000000000000005 R08: 0000000000000000 R09: 00007ffdd4ed8e10 R10: 0000000000000000 R11: 0000000000000293 R12: 00007feb2b247e34 R13: 00007ffdd4ed8ec0 R14: 0000000000000000 R15: 00007ffdd4ed9aa0 </TASK> netdevsim netdevsim4 netdevsim0: renamed from eth0 netdevsim netdevsim4 netdevsim1: renamed from eth1 netdevsim netdevsim4 netdevsim2: renamed from eth2 netdevsim netdevsim4 netdevsim3: renamed from eth3 8021q: adding VLAN 0 to HW filter on device bond0 8021q: adding VLAN 0 to HW filter on device team0 8021q: adding VLAN 0 to HW filter on device batadv0 veth0_vlan: entered promiscuous mode veth1_vlan: entered promiscuous mode veth0_macvtap: entered promiscuous mode veth1_macvtap: entered promiscuous mode batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: batadv0: Interface activated: batadv_slave_0 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: batadv0: Interface activated: batadv_slave_1 netdevsim netdevsim4 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim4 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim4 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim4 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0 ieee80211 phy54: Selected rate control algorithm 'minstrel_ht' ieee80211 phy55: Selected rate control algorithm 'minstrel_ht'

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I hope it helps. Best regards Jianzhou Zhao