R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffeb86029bf R14: 00007f5f7e5a5300 R15: 0000000000022000 ====================================================== WARNING: possible circular locking dependency detected 5.18.0-rc4-syzkaller-00083-g259b897e5a79 #0 Not tainted ------------------------------------------------------ syz-executor.3/1996 is trying to acquire lock: ffff8880891080a8 ((&sq->pending_timer)){+.-.}-{0:0}, at: del_timer_sync+0x33/0x1b0 kernel/time/timer.c:1363 but task is already holding lock: ffffffff90731e90 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] ffffffff90731e90 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1441 [inline] ffffffff90731e90 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1e7/0x4e0 block/blk-cgroup.c:1423 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&blkcg->lock){....}-{2:2}: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:349 [inline] blkg_create+0x47b/0x1030 block/blk-cgroup.c:301 blkcg_init_queue+0xfe/0x810 block/blk-cgroup.c:1206 __alloc_disk_node+0x260/0x610 block/genhd.c:1381 __blk_alloc_disk+0x35/0x70 block/genhd.c:1421 brd_alloc.part.0+0x27f/0x7a0 drivers/block/brd.c:391 brd_alloc drivers/block/brd.c:374 [inline] brd_init+0x1b8/0x24b drivers/block/brd.c:477 do_one_initcall+0x103/0x650 init/main.c:1298 do_initcall_level init/main.c:1371 [inline] do_initcalls init/main.c:1387 [inline] do_basic_setup init/main.c:1406 [inline] kernel_init_freeable+0x6b1/0x73a init/main.c:1613 kernel_init+0x1a/0x1d0 init/main.c:1502 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 -> #1 (&q->queue_lock){..-.}-{2:2}: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0x32/0x50 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:374 [inline] throtl_pending_timer_fn+0xf7/0x1690 block/blk-throttle.c:1152 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x679/0xa80 kernel/time/timer.c:1737 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1750 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645 lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5609 __fs_reclaim_acquire mm/page_alloc.c:4572 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4586 might_alloc include/linux/sched/mm.h:262 [inline] slab_pre_alloc_hook mm/slab.h:722 [inline] slab_alloc_node mm/slub.c:3131 [inline] slab_alloc mm/slub.c:3225 [inline] __kmem_cache_alloc_lru mm/slub.c:3232 [inline] kmem_cache_alloc+0x3e/0x3b0 mm/slub.c:3242 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138 getname_flags include/linux/audit.h:323 [inline] getname+0x8e/0xd0 fs/namei.c:217 do_sys_openat2+0xf5/0x4c0 fs/open.c:1207 do_sys_open fs/open.c:1229 [inline] __do_sys_openat fs/open.c:1245 [inline] __se_sys_openat fs/open.c:1240 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1240 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 ((&sq->pending_timer)){+.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3065 [inline] check_prevs_add kernel/locking/lockdep.c:3188 [inline] validate_chain kernel/locking/lockdep.c:3803 [inline] __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5029 lock_acquire kernel/locking/lockdep.c:5641 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1364 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy block/blk-cgroup.c:1445 [inline] blkcg_deactivate_policy+0x2d2/0x4e0 block/blk-cgroup.c:1423 blk_throtl_exit+0x8a/0x1a0 block/blk-throttle.c:2335 blkcg_init_queue+0x225/0x810 block/blk-cgroup.c:1226 __alloc_disk_node+0x260/0x610 block/genhd.c:1381 __blk_mq_alloc_disk+0x133/0x1c0 block/blk-mq.c:3931 nbd_dev_add+0x3b2/0xcd0 drivers/block/nbd.c:1765 nbd_genl_connect+0x11f3/0x1930 drivers/block/nbd.c:1948 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:731 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline] genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:792 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2503 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:725 ____sys_sendmsg+0x6e2/0x800 net/socket.c:2413 ___sys_sendmsg+0xf3/0x170 net/socket.c:2467 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2496 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (&sq->pending_timer) --> &q->queue_lock --> &blkcg->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&blkcg->lock); lock(&q->queue_lock); lock(&blkcg->lock); lock((&sq->pending_timer)); *** DEADLOCK *** 4 locks held by syz-executor.3/1996: #0: ffffffff8d5fea50 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:802 #1: ffffffff8d5feb08 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline] #1: ffffffff8d5feb08 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x3e0/0x580 net/netlink/genetlink.c:790 #2: ffff888042fa3f10 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:374 [inline] #2: ffff888042fa3f10 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1434 [inline] #2: ffff888042fa3f10 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy+0xfe/0x4e0 block/blk-cgroup.c:1423 #3: ffffffff90731e90 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #3: ffffffff90731e90 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1441 [inline] #3: ffffffff90731e90 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1e7/0x4e0 block/blk-cgroup.c:1423 stack backtrace: CPU: 0 PID: 1996 Comm: syz-executor.3 Not tainted 5.18.0-rc4-syzkaller-00083-g259b897e5a79 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2145 check_prev_add kernel/locking/lockdep.c:3065 [inline] check_prevs_add kernel/locking/lockdep.c:3188 [inline] validate_chain kernel/locking/lockdep.c:3803 [inline] __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5029 lock_acquire kernel/locking/lockdep.c:5641 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1364 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy block/blk-cgroup.c:1445 [inline] blkcg_deactivate_policy+0x2d2/0x4e0 block/blk-cgroup.c:1423 blk_throtl_exit+0x8a/0x1a0 block/blk-throttle.c:2335 blkcg_init_queue+0x225/0x810 block/blk-cgroup.c:1226 __alloc_disk_node+0x260/0x610 block/genhd.c:1381 __blk_mq_alloc_disk+0x133/0x1c0 block/blk-mq.c:3931 nbd_dev_add+0x3b2/0xcd0 drivers/block/nbd.c:1765 nbd_genl_connect+0x11f3/0x1930 drivers/block/nbd.c:1948 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:731 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline] genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:792 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2503 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:725 ____sys_sendmsg+0x6e2/0x800 net/socket.c:2413 ___sys_sendmsg+0xf3/0x170 net/socket.c:2467 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2496 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f5f7d4890e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5f7e5a5168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f5f7d59bf60 RCX: 00007f5f7d4890e9 RDX: 0000000000000000 RSI: 00000000200002c0 RDI: 0000000000000005 RBP: 00007f5f7e5a51d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffeb86029bf R14: 00007f5f7e5a5300 R15: 0000000000022000 nbd: failed to add new device