====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.3.345/7209 is trying to acquire lock: ffffffff8e768728 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0xed8/0x1b70 mm/percpu.c:1782 but task is already holding lock: ffff888027e39cf8 (&q->q_usage_counter(io) #49){++++}-{0:0} , at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] , at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] , 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)#49){++++}-{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_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa54/0xc30 net/socket.c:2592 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646 __sys_sendmsg+0x170/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 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)#49 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#49); lock(fs_reclaim); lock(&q->q_usage_counter(io)#49); lock(pcpu_alloc_mutex); *** DEADLOCK *** 6 locks held by syz.3.345/7209: #0: ffffffff9049ffd0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff904a0088 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff904a0088 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff904a0088 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffffffff904a0088 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x57b/0x800 net/netlink/genetlink.c:1209 #2: ffff88802842a9d0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x91/0x1190 block/blk-mq.c:5183 #3: ffff88802842a8d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xa4/0x1190 block/blk-mq.c:5184 #4: ffff888027e39cf8 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #4: ffff888027e39cf8 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] #4: ffff888027e39cf8 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x88e/0x1190 block/blk-mq.c:5185 #5: ffff888027e39d30 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #5: ffff888027e39d30 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] #5: ffff888027e39d30 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: blk_mq_update_nr_hw_queues+0x88e/0x1190 block/blk-mq.c:5185 stack backtrace: CPU: 1 UID: 0 PID: 7209 Comm: syz.3.345 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_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa54/0xc30 net/socket.c:2592 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646 __sys_sendmsg+0x170/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f10ad99aeb9 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:00007f10ae8b0028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f10adc15fa0 RCX: 00007f10ad99aeb9 RDX: 0000000000000004 RSI: 0000200000002300 RDI: 0000000000000004 RBP: 00007f10ada08c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f10adc16038 R14: 00007f10adc15fa0 R15: 00007ffdef404918