====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.2.881/8781 is trying to acquire lock: ffffffff8e53c768 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0xb5a/0x1470 mm/percpu.c:1782 but task is already holding lock: ffff888027db8060 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] ffff888027db8060 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5132 [inline] ffff888027db8060 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x8ad/0x1280 block/blk-mq.c:5186 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#51){++++}-{0:0}: blk_alloc_queue+0x610/0x750 block/blk-core.c:461 blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4415 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4462 nbd_dev_add+0x492/0xbb0 drivers/block/nbd.c:1954 nbd_init+0x181/0x320 drivers/block/nbd.c:2692 do_one_initcall+0x123/0x680 init/main.c:1378 do_initcall_level init/main.c:1440 [inline] do_initcalls init/main.c:1456 [inline] do_basic_setup init/main.c:1475 [inline] kernel_init_freeable+0x5c8/0x920 init/main.c:1688 kernel_init+0x1c/0x2b0 init/main.c:1578 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4301 [inline] fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4315 might_alloc include/linux/sched/mm.h:317 [inline] prepare_alloc_pages+0x162/0x670 mm/page_alloc.c:4978 __alloc_frozen_pages_noprof+0x18b/0x2430 mm/page_alloc.c:5199 __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:5244 __alloc_pages_node_noprof include/linux/gfp.h:285 [inline] alloc_pages_node_noprof include/linux/gfp.h:312 [inline] pcpu_alloc_pages mm/percpu-vm.c:95 [inline] pcpu_populate_chunk+0x110/0xb10 mm/percpu-vm.c:285 pcpu_alloc_noprof+0x86b/0x1470 mm/percpu.c:1870 iommu_dma_init_fq_percpu drivers/iommu/dma-iommu.c:320 [inline] iommu_dma_init_fq+0x202/0x8a0 drivers/iommu/dma-iommu.c:346 iommu_dma_init_domain drivers/iommu/dma-iommu.c:709 [inline] iommu_setup_dma_ops+0x1336/0x1700 drivers/iommu/dma-iommu.c:2108 bus_iommu_probe drivers/iommu/iommu.c:1952 [inline] iommu_device_register+0x3e3/0x7d0 drivers/iommu/iommu.c:278 intel_iommu_init+0x25e3/0x3780 drivers/iommu/intel/iommu.c:2662 pci_iommu_init+0x31/0x90 arch/x86/kernel/pci-dma.c:174 do_one_initcall+0x123/0x680 init/main.c:1378 do_initcall_level init/main.c:1440 [inline] do_initcalls init/main.c:1456 [inline] do_basic_setup init/main.c:1475 [inline] kernel_init_freeable+0x5c8/0x920 init/main.c:1688 kernel_init+0x1c/0x2b0 init/main.c:1578 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #0 (pcpu_alloc_mutex){+.+.}-{4:4}: 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+0x1669/0x2890 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776 pcpu_alloc_noprof+0xb5a/0x1470 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2ff/0x770 lib/sbitmap.c:126 sbitmap_queue_init_node+0x40/0x4a0 lib/sbitmap.c:454 bt_alloc block/blk-mq-tag.c:546 [inline] blk_mq_init_tags+0x17f/0x320 block/blk-mq-tag.c:571 blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] blk_mq_alloc_map_and_rqs+0x222/0xeb0 block/blk-mq.c:4114 __blk_mq_alloc_map_and_rqs block/blk-mq.c:4136 [inline] __blk_mq_alloc_map_and_rqs+0x128/0x1f0 block/blk-mq.c:4127 blk_mq_realloc_tag_set_tags block/blk-mq.c:4803 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5134 [inline] blk_mq_update_nr_hw_queues+0xad5/0x1280 block/blk-mq.c:5186 nbd_start_device+0x1b0/0xd70 drivers/block/nbd.c:1489 nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline] __nbd_ioctl drivers/block/nbd.c:1623 [inline] nbd_ioctl+0x219/0xda0 drivers/block/nbd.c:1663 blkdev_ioctl+0x5b0/0x6e0 block/ioctl.c:791 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/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: pcpu_alloc_mutex --> fs_reclaim --> &q->q_usage_counter(io)#51 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#51); lock(fs_reclaim); lock(&q->q_usage_counter(io)#51); lock(pcpu_alloc_mutex); *** DEADLOCK *** 4 locks held by syz.2.881/8781: #0: ffff888027db01d0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x91/0x1280 block/blk-mq.c:5184 #1: ffff888027db00d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xa4/0x1280 block/blk-mq.c:5185 #2: ffff888027db8060 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #2: ffff888027db8060 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5132 [inline] #2: ffff888027db8060 (&q->q_usage_counter(io)#51){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x8ad/0x1280 block/blk-mq.c:5186 #3: ffff888027db8098 (&q->q_usage_counter(queue)#35){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #3: ffff888027db8098 (&q->q_usage_counter(queue)#35){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5132 [inline] #3: ffff888027db8098 (&q->q_usage_counter(queue)#35){+.+.}-{0:0}, at: blk_mq_update_nr_hw_queues+0x8ad/0x1280 block/blk-mq.c:5186 stack backtrace: CPU: 3 UID: 0 PID: 8781 Comm: syz.2.881 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x340 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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+0x1669/0x2890 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776 pcpu_alloc_noprof+0xb5a/0x1470 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2ff/0x770 lib/sbitmap.c:126 sbitmap_queue_init_node+0x40/0x4a0 lib/sbitmap.c:454 bt_alloc block/blk-mq-tag.c:546 [inline] blk_mq_init_tags+0x17f/0x320 block/blk-mq-tag.c:571 blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] blk_mq_alloc_map_and_rqs+0x222/0xeb0 block/blk-mq.c:4114 __blk_mq_alloc_map_and_rqs block/blk-mq.c:4136 [inline] __blk_mq_alloc_map_and_rqs+0x128/0x1f0 block/blk-mq.c:4127 blk_mq_realloc_tag_set_tags block/blk-mq.c:4803 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5134 [inline] blk_mq_update_nr_hw_queues+0xad5/0x1280 block/blk-mq.c:5186 nbd_start_device+0x1b0/0xd70 drivers/block/nbd.c:1489 nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline] __nbd_ioctl drivers/block/nbd.c:1623 [inline] nbd_ioctl+0x219/0xda0 drivers/block/nbd.c:1663 blkdev_ioctl+0x5b0/0x6e0 block/ioctl.c:791 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f964438f7c9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f96425f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f96445e6090 RCX: 00007f964438f7c9 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 00007f9644413f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f96445e6128 R14: 00007f96445e6090 R15: 00007fff09d494d8