FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 1, space 0, times 984
CPU: 0 UID: 0 PID: 5331 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x40c/0x560 lib/fault-inject.c:174
 should_failslab+0xa8/0x100 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4539 [inline]
 slab_alloc_node mm/slub.c:4897 [inline]
 kmem_cache_alloc_noprof+0xa6/0x5f0 mm/slub.c:4931
 lsm_inode_alloc security/security.c:254 [inline]
 security_inode_alloc+0x39/0x310 security/security.c:1215
 inode_init_always_gfp+0x97e/0xd30 fs/inode.c:298
 inode_init_always include/linux/fs.h:2945 [inline]
 alloc_inode+0x82/0x1b0 fs/inode.c:345
 new_inode+0x1f/0x170 fs/inode.c:1174
 debugfs_get_inode fs/debugfs/inode.c:72 [inline]
 __debugfs_create_file+0xb8/0x400 fs/debugfs/inode.c:433
 debugfs_create_file_full+0x3f/0x60 fs/debugfs/inode.c:460
 kvm_create_vm_debugfs+0x6ec/0x8f0 virt/kvm/kvm_main.c:1057
 kvm_create_vm virt/kvm/kvm_main.c:1196 [inline]
 kvm_dev_ioctl_create_vm virt/kvm/kvm_main.c:5493 [inline]
 kvm_dev_ioctl+0x1362/0x1770 virt/kvm/kvm_main.c:5535
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb979d9df99
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:00007fb97abd0fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb97a025fa0 RCX: 00007fb979d9df99
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000005
RBP: 00007fb979e34ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb97a026038 R14: 00007fb97a025fa0 R15: 00007fffdb8636a8
 </TASK>
debugfs: out of free dentries, can not create file 'io_exits'
faux_driver vgem: [drm] Unknown color mode 4099; guessing buffer size.

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.0/5331 is trying to acquire lock:
ffffffff8ec61160 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0x231/0x1900 mm/percpu.c:1788

but task is already holding lock:
ffff888034b1c6b8 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x1af/0x480 block/elevator.c:679

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       elevator_change+0x1af/0x480 block/elevator.c:679
       elv_iosched_store+0x504/0x630 block/elevator.c:826
       queue_attr_store+0x207/0x2b0 block/blk-sysfs.c:906
       kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#17){++++}-{0:0}:
       blk_alloc_queue+0x544/0x690 block/blk-core.c:504
       blk_mq_alloc_queue block/blk-mq.c:4420 [inline]
       __blk_mq_alloc_disk+0x194/0x390 block/blk-mq.c:4467
       loop_add+0x480/0xb40 drivers/block/loop.c:2041
       loop_init+0xd7/0x160 drivers/block/loop.c:2280
       do_one_initcall+0x250/0x870 init/main.c:1347
       do_initcall_level+0x10a/0x1a0 init/main.c:1409
       do_initcalls+0x59/0xa0 init/main.c:1425
       kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
       kernel_init+0x1d/0x1d0 init/main.c:1548
       ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4329 [inline]
       fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4343
       might_alloc include/linux/sched/mm.h:317 [inline]
       prepare_alloc_pages+0x15b/0x650 mm/page_alloc.c:5048
       __alloc_frozen_pages_noprof+0x12f/0x380 mm/page_alloc.c:5293
       __alloc_pages_noprof+0x10/0x100 mm/page_alloc.c:5338
       __alloc_pages_node_noprof include/linux/gfp.h:291 [inline]
       alloc_pages_node_noprof include/linux/gfp.h:318 [inline]
       pcpu_alloc_pages mm/percpu-vm.c:95 [inline]
       pcpu_populate_chunk+0x181/0xb30 mm/percpu-vm.c:285
       pcpu_alloc_noprof+0xbca/0x1900 mm/percpu.c:1876
       iommu_dma_init_fq_percpu drivers/iommu/dma-iommu.c:321 [inline]
       iommu_dma_init_fq+0x2d3/0x700 drivers/iommu/dma-iommu.c:347
       iommu_dma_init_domain drivers/iommu/dma-iommu.c:720 [inline]
       iommu_setup_dma_ops+0x6e5/0x1820 drivers/iommu/dma-iommu.c:2159
       bus_iommu_probe+0x296/0x470 drivers/iommu/iommu.c:1983
       iommu_device_register+0x1af/0x210 drivers/iommu/iommu.c:307
       intel_iommu_init+0x6f0/0x8e0 drivers/iommu/intel/iommu.c:2662
       pci_iommu_init+0x38/0x70 arch/x86/kernel/pci-dma.c:174
       do_one_initcall+0x250/0x870 init/main.c:1347
       do_initcall_level+0x10a/0x1a0 init/main.c:1409
       do_initcalls+0x59/0xa0 init/main.c:1425
       kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
       kernel_init+0x1d/0x1d0 init/main.c:1548
       ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       pcpu_alloc_noprof+0x231/0x1900 mm/percpu.c:1788
       __percpu_counter_init_many+0x42/0x380 lib/percpu_counter.c:198
       blkg_rwstat_init+0x2c/0x170 block/blk-cgroup-rwstat.c:12
       bfqg_stats_init block/bfq-cgroup.c:459 [inline]
       bfq_pd_alloc+0xb6/0x390 block/bfq-cgroup.c:521
       blkcg_activate_policy+0x650/0xb10 block/blk-cgroup.c:1599
       bfq_create_group_hierarchy+0x62/0x120 block/bfq-cgroup.c:1258
       bfq_init_queue+0xbca/0x1300 block/bfq-iosched.c:7341
       blk_mq_init_sched+0x2e9/0x620 block/blk-mq-sched.c:643
       elevator_switch+0x26f/0x7b0 block/elevator.c:584
       elevator_change+0x2fa/0x480 block/elevator.c:681
       elv_iosched_store+0x504/0x630 block/elevator.c:826
       queue_attr_store+0x207/0x2b0 block/blk-sysfs.c:906
       kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 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 --> &q->q_usage_counter(io)#17 --> &q->elevator_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&q->elevator_lock);
                               lock(&q->q_usage_counter(io)#17);
                               lock(&q->elevator_lock);
  lock(pcpu_alloc_mutex);

 *** DEADLOCK ***

8 locks held by syz.0.0/5331:
 #0: ffff88803804a2b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff88803f32a450 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff88803f32a450 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffff88800e73a480 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
 #3: ffff8880357f70f8 (kn->active#66){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #3: ffff8880357f70f8 (kn->active#66){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337
 #4: ffff8880359753a0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: elv_iosched_store+0x498/0x630 block/elevator.c:821
 #5: ffff888034b1c190 (&q->q_usage_counter(io)#17){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline]
 #5: ffff888034b1c190 (&q->q_usage_counter(io)#17){++++}-{0:0}, at: elevator_change+0x194/0x480 block/elevator.c:668
 #6: ffff888034b1c1c8 (&q->q_usage_counter(queue)){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline]
 #6: ffff888034b1c1c8 (&q->q_usage_counter(queue)){+.+.}-{0:0}, at: elevator_change+0x194/0x480 block/elevator.c:668
 #7: ffff888034b1c6b8 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x1af/0x480 block/elevator.c:679

stack backtrace:
CPU: 0 UID: 0 PID: 5331 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
 pcpu_alloc_noprof+0x231/0x1900 mm/percpu.c:1788
 __percpu_counter_init_many+0x42/0x380 lib/percpu_counter.c:198
 blkg_rwstat_init+0x2c/0x170 block/blk-cgroup-rwstat.c:12
 bfqg_stats_init block/bfq-cgroup.c:459 [inline]
 bfq_pd_alloc+0xb6/0x390 block/bfq-cgroup.c:521
 blkcg_activate_policy+0x650/0xb10 block/blk-cgroup.c:1599
 bfq_create_group_hierarchy+0x62/0x120 block/bfq-cgroup.c:1258
 bfq_init_queue+0xbca/0x1300 block/bfq-iosched.c:7341
 blk_mq_init_sched+0x2e9/0x620 block/blk-mq-sched.c:643
 elevator_switch+0x26f/0x7b0 block/elevator.c:584
 elevator_change+0x2fa/0x480 block/elevator.c:681
 elv_iosched_store+0x504/0x630 block/elevator.c:826
 queue_attr_store+0x207/0x2b0 block/blk-sysfs.c:906
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb979d9df99
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:00007fb97abd0fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb97a025fa0 RCX: 00007fb979d9df99
RDX: 0000000000000003 RSI: 0000200000000300 RDI: 0000000000000008
RBP: 00007fb979e34ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb97a026038 R14: 00007fb97a025fa0 R15: 00007fffdb8636a8
 </TASK>