loop8: detected capacity change from 16384 to 0 ====================================================== WARNING: possible circular locking dependency detected 6.15.0-syzkaller-13743-g8630c59e9936 #0 Not tainted ------------------------------------------------------ syz.1.44/3580 is trying to acquire lock: ffff800088b48868 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] ffff800088b48868 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline] ffff800088b48868 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_env+0x654/0x1260 lib/kobject_uevent.c:608 but task is already holding lock: ffff000014945868 (&q->q_usage_counter(io)#25){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:205 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#25){++++}-{0:0}: blk_alloc_queue+0x534/0x640 block/blk-core.c:461 blk_mq_alloc_queue+0x14c/0x22c block/blk-mq.c:4396 __blk_mq_alloc_disk+0x20/0x1a4 block/blk-mq.c:4443 loop_add+0x3bc/0x944 drivers/block/loop.c:2014 loop_init+0xd0/0x138 drivers/block/loop.c:2249 do_one_initcall+0x130/0x7f0 init/main.c:1273 do_initcall_level init/main.c:1335 [inline] do_initcalls init/main.c:1351 [inline] do_basic_setup init/main.c:1370 [inline] kernel_init_freeable+0x48c/0x6f4 init/main.c:1583 kernel_init+0x24/0x1dc init/main.c:1473 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4045 [inline] fs_reclaim_acquire+0x138/0x160 mm/page_alloc.c:4059 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4099 [inline] slab_alloc_node mm/slub.c:4177 [inline] kmem_cache_alloc_node_noprof+0x64/0x3b8 mm/slub.c:4249 __alloc_skb+0x208/0x2f0 net/core/skbuff.c:660 alloc_skb include/linux/skbuff.h:1336 [inline] alloc_uevent_skb+0x84/0x1f0 lib/kobject_uevent.c:289 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline] kobject_uevent_env+0x998/0x1260 lib/kobject_uevent.c:608 kobject_synth_uevent+0x4cc/0x61c lib/kobject_uevent.c:207 bus_uevent_store+0x38/0x6c drivers/base/bus.c:832 bus_attr_store+0x60/0x9c drivers/base/bus.c:172 sysfs_kf_write+0xc4/0x10c fs/sysfs/file.c:145 kernfs_fop_write_iter+0x254/0x3e4 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x4b0/0xad4 fs/read_write.c:686 ksys_write+0xec/0x1d8 fs/read_write.c:738 __do_sys_write fs/read_write.c:749 [inline] __se_sys_write fs/read_write.c:746 [inline] __arm64_sys_write+0x6c/0x9c fs/read_write.c:746 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x50/0x198 arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x10c/0x138 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #0 (uevent_sock_mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1638/0x2380 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x310/0x38c kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x144/0x9d8 kernel/locking/mutex.c:747 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:799 uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline] kobject_uevent_env+0x654/0x1260 lib/kobject_uevent.c:608 kobject_uevent+0x14/0x20 lib/kobject_uevent.c:656 loop_set_size drivers/block/loop.c:211 [inline] loop_set_size drivers/block/loop.c:208 [inline] loop_set_status+0x6f0/0x924 drivers/block/loop.c:1254 loop_set_status_compat+0xac/0xf4 drivers/block/loop.c:1630 lo_compat_ioctl+0xd0/0x1b4 drivers/block/loop.c:1656 compat_blkdev_ioctl+0x1f8/0x860 block/ioctl.c:760 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __arm64_compat_sys_ioctl+0x1d0/0x238 fs/ioctl.c:948 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc_compat+0x40/0x68 arch/arm64/kernel/syscall.c:157 el0_svc_compat+0x4c/0x17c arch/arm64/kernel/entry-common.c:911 el0t_32_sync_handler+0x98/0x13c arch/arm64/kernel/entry-common.c:921 el0t_32_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:605 other info that might help us debug this: Chain exists of: uevent_sock_mutex --> fs_reclaim --> &q->q_usage_counter(io)#25 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#25); lock(fs_reclaim); lock(&q->q_usage_counter(io)#25); lock(uevent_sock_mutex); *** DEADLOCK *** 3 locks held by syz.1.44/3580: #0: ffff000014a5f400 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_set_status+0x34/0x924 drivers/block/loop.c:1223 #1: ffff000014945868 (&q->q_usage_counter(io)#25){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:205 #2: ffff0000149458a0 (&q->q_usage_counter(queue)#20){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:205 stack backtrace: CPU: 1 UID: 0 PID: 3580 Comm: syz.1.44 Not tainted 6.15.0-syzkaller-13743-g8630c59e9936 #0 PREEMPT Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xa4/0xf4 lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x28c/0x370 kernel/locking/lockdep.c:2046 check_noncircular+0x168/0x17c kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1638/0x2380 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x310/0x38c kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x144/0x9d8 kernel/locking/mutex.c:747 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:799 uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline] kobject_uevent_env+0x654/0x1260 lib/kobject_uevent.c:608 kobject_uevent+0x14/0x20 lib/kobject_uevent.c:656 loop_set_size drivers/block/loop.c:211 [inline] loop_set_size drivers/block/loop.c:208 [inline] loop_set_status+0x6f0/0x924 drivers/block/loop.c:1254 loop_set_status_compat+0xac/0xf4 drivers/block/loop.c:1630 lo_compat_ioctl+0xd0/0x1b4 drivers/block/loop.c:1656 compat_blkdev_ioctl+0x1f8/0x860 block/ioctl.c:760 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __arm64_compat_sys_ioctl+0x1d0/0x238 fs/ioctl.c:948 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc_compat+0x40/0x68 arch/arm64/kernel/syscall.c:157 el0_svc_compat+0x4c/0x17c arch/arm64/kernel/entry-common.c:911 el0t_32_sync_handler+0x98/0x13c arch/arm64/kernel/entry-common.c:921 el0t_32_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:605