====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.0.3470/15728 is trying to acquire lock: ffffffff8ea843c0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline] ffffffff8ea843c0 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4520 [inline] ffffffff8ea843c0 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4875 [inline] ffffffff8ea843c0 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_noprof+0x40/0x650 mm/slub.c:4905 but task is already holding lock: ffffffff8ea66bc8 (slab_mutex){+.+.}-{4:4}, at: __kmem_cache_create_args+0x58/0x440 mm/slab_common.c:350 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #7 (slab_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794 kmem_cache_destroy+0x64/0x170 mm/slab_common.c:557 p9_client_destroy+0x4ab/0x500 net/9p/client.c:965 v9fs_session_close+0x4f/0x200 fs/9p/v9fs.c:539 v9fs_kill_super+0x5c/0x90 fs/9p/vfs_super.c:175 deactivate_locked_super+0xbc/0x130 fs/super.c:476 v9fs_get_tree+0x846/0xac0 fs/9p/vfs_super.c:156 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3764 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3840 do_mount fs/namespace.c:4173 [inline] __do_sys_mount fs/namespace.c:4372 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4349 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #6 (cpu_hotplug_lock){++++}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read include/linux/percpu-rwsem.h:77 [inline] cpus_read_lock+0x42/0x160 kernel/cpu.c:490 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 nbd_reconnect_socket drivers/block/nbd.c:1342 [inline] nbd_genl_reconfigure+0x132f/0x1ea0 drivers/block/nbd.c:2431 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x112/0x150 net/socket.c:796 __sock_sendmsg net/socket.c:811 [inline] ____sys_sendmsg+0x589/0x8c0 net/socket.c:2668 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2722 __sys_sendmsg net/socket.c:2754 [inline] __do_sys_sendmsg net/socket.c:2759 [inline] __se_sys_sendmsg net/socket.c:2757 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2757 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xdcc/0x1600 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386 blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x28d/0x580 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2f4/0xa40 block/blk-core.c:753 submit_bh fs/buffer.c:2842 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2444 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2502 do_read_cache_folio+0x358/0x590 mm/filemap.c:4107 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:723 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694 blkdev_get_whole+0x380/0x510 block/bdev.c:764 bdev_open+0x31e/0xd30 block/bdev.c:973 blkdev_open+0x470/0x610 block/fops.c:697 do_dentry_open+0x785/0x14e0 fs/open.c:949 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4693 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4852 do_file_open+0x23e/0x4a0 fs/namei.c:4881 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&cmd->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794 nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xdcc/0x1600 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386 blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x28d/0x580 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2f4/0xa40 block/blk-core.c:753 submit_bh fs/buffer.c:2842 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2444 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2502 do_read_cache_folio+0x358/0x590 mm/filemap.c:4107 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:723 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694 blkdev_get_whole+0x380/0x510 block/bdev.c:764 bdev_open+0x31e/0xd30 block/bdev.c:973 blkdev_open+0x470/0x610 block/fops.c:697 do_dentry_open+0x785/0x14e0 fs/open.c:949 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4693 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4852 do_file_open+0x23e/0x4a0 fs/namei.c:4881 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (set->srcu){.+.+}-{0:0}: srcu_lock_sync include/linux/srcu.h:199 [inline] __synchronize_srcu+0xca/0x3e0 kernel/rcu/srcutree.c:1505 elevator_switch+0x1e8/0x7a0 block/elevator.c:576 elevator_change+0x2cc/0x450 block/elevator.c:681 elevator_set_default+0x36c/0x430 block/elevator.c:754 blk_register_queue+0x3e9/0x4e0 block/blk-sysfs.c:987 __add_disk+0x677/0xd50 block/genhd.c:528 add_disk_fwnode+0xfb/0x480 block/genhd.c:597 add_disk include/linux/blkdev.h:793 [inline] nbd_dev_add+0x72c/0xb50 drivers/block/nbd.c:1984 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692 do_one_initcall+0x250/0x870 init/main.c:1386 do_initcall_level+0x104/0x190 init/main.c:1448 do_initcalls+0x59/0xa0 init/main.c:1464 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1696 kernel_init+0x1d/0x1d0 init/main.c:1586 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794 elevator_change+0x1b3/0x450 block/elevator.c:679 elevator_set_none+0xb5/0x140 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5131 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5176 [inline] blk_mq_update_nr_hw_queues+0x5e7/0x1a60 block/blk-mq.c:5241 nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1489 nbd_genl_connect+0x165b/0x1cf0 drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x112/0x150 net/socket.c:796 __sock_sendmsg net/socket.c:811 [inline] ____sys_sendmsg+0x589/0x8c0 net/socket.c:2668 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2722 __sys_sendmsg net/socket.c:2754 [inline] __do_sys_sendmsg net/socket.c:2759 [inline] __se_sys_sendmsg net/socket.c:2757 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2757 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#49){++++}-{0:0}: blk_alloc_queue+0x546/0x680 block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4450 [inline] __blk_mq_alloc_disk+0x197/0x390 block/blk-mq.c:4497 nbd_dev_add+0x499/0xb50 drivers/block/nbd.c:1954 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692 do_one_initcall+0x250/0x870 init/main.c:1386 do_initcall_level+0x104/0x190 init/main.c:1448 do_initcalls+0x59/0xa0 init/main.c:1464 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1696 kernel_init+0x1d/0x1d0 init/main.c:1586 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (fs_reclaim){+.+.}-{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+0x106/0x350 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4312 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4326 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] kmem_cache_alloc_noprof+0x40/0x650 mm/slub.c:4905 create_cache mm/slab_common.c:249 [inline] __kmem_cache_create_args+0x2eb/0x440 mm/slab_common.c:380 __kmem_cache_create include/linux/slab.h:390 [inline] ieee80211s_init net/mac80211/mesh.c:28 [inline] ieee80211_mesh_init_sdata+0x371/0x620 net/mac80211/mesh.c:1792 ieee80211_setup_sdata+0x80e/0xb50 net/mac80211/iface.c:1926 ieee80211_if_change_type+0x146/0x940 net/mac80211/iface.c:2065 ieee80211_change_iface+0xd5/0x510 net/mac80211/cfg.c:271 rdev_change_virtual_intf net/wireless/rdev-ops.h:74 [inline] cfg80211_change_iface+0x6bf/0xe70 net/wireless/util.c:1218 nl80211_set_interface+0x773/0xa90 net/wireless/nl80211.c:4722 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x112/0x150 net/socket.c:796 __sock_sendmsg net/socket.c:811 [inline] ____sys_sendmsg+0x589/0x8c0 net/socket.c:2668 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2722 __sys_sendmsg net/socket.c:2754 [inline] __do_sys_sendmsg net/socket.c:2759 [inline] __se_sys_sendmsg net/socket.c:2757 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2757 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: fs_reclaim --> cpu_hotplug_lock --> slab_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slab_mutex); lock(cpu_hotplug_lock); lock(slab_mutex); lock(fs_reclaim); *** DEADLOCK *** 4 locks held by syz.0.3470/15728: #0: ffffffff8fe64a48 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8fdf6540 (rtnl_mutex){+.+.}-{4:4}, at: nl80211_pre_doit+0x5f/0x8e0 net/wireless/nl80211.c:18128 #2: ffff888071b80780 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: wiphy_lock include/net/cfg80211.h:6428 [inline] #2: ffff888071b80780 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: nl80211_pre_doit+0x281/0x8e0 net/wireless/nl80211.c:18201 #3: ffffffff8ea66bc8 (slab_mutex){+.+.}-{4:4}, at: __kmem_cache_create_args+0x58/0x440 mm/slab_common.c:350 stack backtrace: CPU: 0 UID: 0 PID: 15728 Comm: syz.0.3470 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: 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+0x106/0x350 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4312 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4326 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] kmem_cache_alloc_noprof+0x40/0x650 mm/slub.c:4905 create_cache mm/slab_common.c:249 [inline] __kmem_cache_create_args+0x2eb/0x440 mm/slab_common.c:380 __kmem_cache_create include/linux/slab.h:390 [inline] ieee80211s_init net/mac80211/mesh.c:28 [inline] ieee80211_mesh_init_sdata+0x371/0x620 net/mac80211/mesh.c:1792 ieee80211_setup_sdata+0x80e/0xb50 net/mac80211/iface.c:1926 ieee80211_if_change_type+0x146/0x940 net/mac80211/iface.c:2065 ieee80211_change_iface+0xd5/0x510 net/mac80211/cfg.c:271 rdev_change_virtual_intf net/wireless/rdev-ops.h:74 [inline] cfg80211_change_iface+0x6bf/0xe70 net/wireless/util.c:1218 nl80211_set_interface+0x773/0xa90 net/wireless/nl80211.c:4722 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x112/0x150 net/socket.c:796 __sock_sendmsg net/socket.c:811 [inline] ____sys_sendmsg+0x589/0x8c0 net/socket.c:2668 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2722 __sys_sendmsg net/socket.c:2754 [inline] __do_sys_sendmsg net/socket.c:2759 [inline] __se_sys_sendmsg net/socket.c:2757 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2757 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fea8059c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fea81370028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fea80816090 RCX: 00007fea8059c799 RDX: 0000000000000010 RSI: 0000200000000180 RDI: 000000000000000a RBP: 00007fea80632c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fea80816128 R14: 00007fea80816090 R15: 00007ffedbcfdc48