====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.1587/12779 is trying to acquire lock: ffffffff8e728908 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0xb4c/0x1470 mm/percpu.c:1782 but task is already holding lock: ffff888105379448 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] ffff888105379448 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x899/0x1200 block/blk-mq.c:5070 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+0x619/0x760 block/blk-core.c:461 blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4400 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4447 nbd_dev_add+0x492/0xbb0 drivers/block/nbd.c:1943 nbd_init+0x181/0x320 drivers/block/nbd.c:2680 do_one_initcall+0x120/0x6e0 init/main.c:1269 do_initcall_level init/main.c:1331 [inline] do_initcalls init/main.c:1347 [inline] do_basic_setup init/main.c:1366 [inline] kernel_init_freeable+0x5c2/0x910 init/main.c:1579 kernel_init+0x1c/0x2b0 init/main.c:1469 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 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:4234 [inline] fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4248 might_alloc include/linux/sched/mm.h:318 [inline] prepare_alloc_pages+0x162/0x610 mm/page_alloc.c:4916 __alloc_frozen_pages_noprof+0x18b/0x23f0 mm/page_alloc.c:5137 __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:5182 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline] alloc_pages_node_noprof include/linux/gfp.h:311 [inline] pcpu_alloc_pages mm/percpu-vm.c:95 [inline] pcpu_populate_chunk+0x110/0xb00 mm/percpu-vm.c:285 pcpu_alloc_noprof+0x86a/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:2106 bus_iommu_probe+0x23e/0x530 drivers/iommu/iommu.c:1911 iommu_device_register+0x1af/0x280 drivers/iommu/iommu.c:277 intel_iommu_init+0x25e7/0x3780 drivers/iommu/intel/iommu.c:3131 pci_iommu_init+0x2e/0x90 arch/x86/kernel/pci-dma.c:174 do_one_initcall+0x120/0x6e0 init/main.c:1269 do_initcall_level init/main.c:1331 [inline] do_initcalls init/main.c:1347 [inline] do_basic_setup init/main.c:1366 [inline] kernel_init_freeable+0x5c2/0x910 init/main.c:1579 kernel_init+0x1c/0x2b0 init/main.c:1469 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 pcpu_alloc_noprof+0xb4c/0x1470 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2fd/0x770 lib/sbitmap.c:126 sbitmap_queue_init_node+0x40/0x4a0 lib/sbitmap.c:454 bt_alloc block/blk-mq-tag.c:542 [inline] blk_mq_init_tags+0x12d/0x2b0 block/blk-mq-tag.c:565 blk_mq_alloc_rq_map block/blk-mq.c:3542 [inline] blk_mq_alloc_map_and_rqs+0x237/0xf60 block/blk-mq.c:4098 __blk_mq_alloc_map_and_rqs block/blk-mq.c:4120 [inline] __blk_mq_alloc_map_and_rqs+0x128/0x1f0 block/blk-mq.c:4111 blk_mq_realloc_tag_set_tags block/blk-mq.c:4759 [inline] __blk_mq_update_nr_hw_queues+0xcc1/0x1200 block/blk-mq.c:5072 blk_mq_update_nr_hw_queues+0x3b/0x60 block/blk-mq.c:5124 nbd_start_device+0x1b0/0xd70 drivers/block/nbd.c:1478 nbd_genl_connect+0x134b/0x1c60 drivers/block/nbd.c:2228 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0xa98/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 __sys_sendmsg+0x16d/0x220 net/socket.c:2700 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 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.0.1587/12779: #0: ffffffff90427f50 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff90428008 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff90428008 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff90428008 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffffffff90428008 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x577/0x800 net/netlink/genetlink.c:1209 #2: ffff8880274d1188 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x27/0x60 block/blk-mq.c:5122 #3: ffff8880274d10d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x31/0x60 block/blk-mq.c:5123 #4: ffff888105379448 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] #4: ffff888105379448 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x899/0x1200 block/blk-mq.c:5070 #5: ffff888105379480 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] #5: ffff888105379480 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x899/0x1200 block/blk-mq.c:5070 stack backtrace: CPU: 2 UID: 0 PID: 12779 Comm: syz.0.1587 Not tainted syzkaller #0 PREEMPT(full) 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+0x275/0x350 kernel/locking/lockdep.c:2043 check_noncircular+0x14c/0x170 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 pcpu_alloc_noprof+0xb4c/0x1470 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2fd/0x770 lib/sbitmap.c:126 sbitmap_queue_init_node+0x40/0x4a0 lib/sbitmap.c:454 bt_alloc block/blk-mq-tag.c:542 [inline] blk_mq_init_tags+0x12d/0x2b0 block/blk-mq-tag.c:565 blk_mq_alloc_rq_map block/blk-mq.c:3542 [inline] blk_mq_alloc_map_and_rqs+0x237/0xf60 block/blk-mq.c:4098 __blk_mq_alloc_map_and_rqs block/blk-mq.c:4120 [inline] __blk_mq_alloc_map_and_rqs+0x128/0x1f0 block/blk-mq.c:4111 blk_mq_realloc_tag_set_tags block/blk-mq.c:4759 [inline] __blk_mq_update_nr_hw_queues+0xcc1/0x1200 block/blk-mq.c:5072 blk_mq_update_nr_hw_queues+0x3b/0x60 block/blk-mq.c:5124 nbd_start_device+0x1b0/0xd70 drivers/block/nbd.c:1478 nbd_genl_connect+0x134b/0x1c60 drivers/block/nbd.c:2228 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0xa98/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 __sys_sendmsg+0x16d/0x220 net/socket.c:2700 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faad538ebe9 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:00007faad612d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007faad55c6090 RCX: 00007faad538ebe9 RDX: 0000000020000000 RSI: 0000200000001ac0 RDI: 0000000000000006 RBP: 00007faad5411e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007faad55c6128 R14: 00007faad55c6090 R15: 00007fff63eb9858 nbd0: detected capacity change from 0 to 127