====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.3.1032/10033 is trying to acquire lock: ffffffff8e767628 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0xed8/0x1b70 mm/percpu.c:1782 but task is already holding lock: ffff888040ff5628 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] ffff888040ff5628 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] ffff888040ff5628 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x88e/0x1190 block/blk-mq.c:5185 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#52){++++}-{0:0}: blk_alloc_queue+0x610/0x750 block/blk-core.c:461 blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4415 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4462 nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x11d/0x690 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+0x6e5/0x790 init/main.c:1688 kernel_init+0x1f/0x1e0 init/main.c:1578 ret_from_fork+0x754/0xaf0 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:4331 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4345 might_alloc include/linux/sched/mm.h:317 [inline] prepare_alloc_pages+0x166/0x5f0 mm/page_alloc.c:5008 __alloc_frozen_pages_noprof+0x193/0x2410 mm/page_alloc.c:5229 __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:5274 __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+0x118/0x990 mm/percpu-vm.c:285 pcpu_alloc_noprof+0x731/0x1b70 mm/percpu.c:1870 iommu_dma_init_fq_percpu drivers/iommu/dma-iommu.c:320 [inline] iommu_dma_init_fq+0x1da/0x7e0 drivers/iommu/dma-iommu.c:346 iommu_dma_init_domain drivers/iommu/dma-iommu.c:709 [inline] iommu_setup_dma_ops+0x1258/0x1630 drivers/iommu/dma-iommu.c:2108 bus_iommu_probe+0x23e/0x530 drivers/iommu/iommu.c:1952 iommu_device_register+0x1af/0x280 drivers/iommu/iommu.c:278 intel_iommu_init+0x2020/0x2970 drivers/iommu/intel/iommu.c:2662 pci_iommu_init+0x3c/0x80 arch/x86/kernel/pci-dma.c:174 do_one_initcall+0x11d/0x690 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+0x6e5/0x790 init/main.c:1688 kernel_init+0x1f/0x1e0 init/main.c:1578 ret_from_fork+0x754/0xaf0 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x17c/0x330 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 pcpu_alloc_noprof+0xed8/0x1b70 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2ff/0x720 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+0x184/0x300 block/blk-mq-tag.c:571 blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] blk_mq_alloc_map_and_rqs+0x218/0xeb0 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:4802 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5133 [inline] blk_mq_update_nr_hw_queues+0xaba/0x1190 block/blk-mq.c:5185 nbd_start_device+0x1a6/0xbd0 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+0x4a6/0xd30 drivers/block/nbd.c:1663 compat_blkdev_ioctl+0x682/0x7b0 block/ioctl.c:848 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x2cf/0x360 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xde/0x660 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Chain exists of: pcpu_alloc_mutex --> fs_reclaim --> &q->q_usage_counter(io)#52 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#52); lock(fs_reclaim); lock(&q->q_usage_counter(io)#52); lock(pcpu_alloc_mutex); *** DEADLOCK *** 4 locks held by syz.3.1032/10033: #0: ffff8880263359d0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x91/0x1190 block/blk-mq.c:5183 #1: ffff8880263358d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xa4/0x1190 block/blk-mq.c:5184 #2: ffff888040ff5628 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #2: ffff888040ff5628 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] #2: ffff888040ff5628 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x88e/0x1190 block/blk-mq.c:5185 #3: ffff888040ff5660 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #3: ffff888040ff5660 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] #3: ffff888040ff5660 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: blk_mq_update_nr_hw_queues+0x88e/0x1190 block/blk-mq.c:5185 stack backtrace: CPU: 0 UID: 0 PID: 10033 Comm: syz.3.1032 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 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x17c/0x330 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 pcpu_alloc_noprof+0xed8/0x1b70 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2ff/0x720 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+0x184/0x300 block/blk-mq-tag.c:571 blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] blk_mq_alloc_map_and_rqs+0x218/0xeb0 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:4802 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5133 [inline] blk_mq_update_nr_hw_queues+0xaba/0x1190 block/blk-mq.c:5185 nbd_start_device+0x1a6/0xbd0 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+0x4a6/0xd30 drivers/block/nbd.c:1663 compat_blkdev_ioctl+0x682/0x7b0 block/ioctl.c:848 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x2cf/0x360 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xde/0x660 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7fc1579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 2e 8d b4 26 00 00 00 00 8d b4 26 00 00 00 RSP: 002b:00000000f546550c EFLAGS: 00000292 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000000ab03 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 block nbd3: shutting down sockets ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 2e 8d b4 26 00 00 00 cs lea 0x0(%rsi,%riz,1),%esi 37: 00 38: 8d .byte 0x8d 39: b4 26 mov $0x26,%ah 3b: 00 00 add %al,(%rax)