syzbot

======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc7-syzkaller-00043-g619f0b6fad52 #0 Not tainted
------------------------------------------------------
kworker/0:7/5892 is trying to acquire lock:
ffff88806b47a3e0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
ffff88806b47a3e0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
ffff88806b47a3e0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4148 [inline]
ffff88806b47a3e0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: __flush_work+0xe9/0xc60 kernel/workqueue.c:4206

but task is already holding lock:
ffff88802865a800 (&q->q_usage_counter(queue)#56){++++}-{0:0}, at: sd_remove+0x8d/0x110 drivers/scsi/sd.c:4072

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&q->q_usage_counter(queue)#56){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       blk_queue_enter+0xe1/0x600 block/blk-core.c:328
       blk_mq_alloc_request+0x4fa/0xaa0 block/blk-mq.c:652
       scsi_alloc_request drivers/scsi/scsi_lib.c:1225 [inline]
       scsi_execute_cmd+0x16c/0x10e0 drivers/scsi/scsi_lib.c:307
       read_capacity_10+0x256/0x9c0 drivers/scsi/sd.c:2766
       sd_read_capacity drivers/scsi/sd.c:2834 [inline]
       sd_revalidate_disk+0x1066/0xbce0 drivers/scsi/sd.c:3734
       sd_probe+0x9fa/0x1100 drivers/scsi/sd.c:4010
       really_probe+0x2ba/0xad0 drivers/base/dd.c:658
       __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
       driver_probe_device+0x50/0x430 drivers/base/dd.c:830
       __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:958
       bus_for_each_drv+0x250/0x2e0 drivers/base/bus.c:459
       __device_attach_async_helper+0x22d/0x300 drivers/base/dd.c:987
       async_run_entry_fn+0xaa/0x420 kernel/async.c:129
       process_one_work kernel/workqueue.c:3236 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3317
       worker_thread+0x870/0xd30 kernel/workqueue.c:3398
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #2 (&q->limits_lock){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       queue_limits_start_update include/linux/blkdev.h:947 [inline]
       loop_reconfigure_limits+0x43f/0x900 drivers/block/loop.c:998
       loop_set_block_size drivers/block/loop.c:1473 [inline]
       lo_simple_ioctl drivers/block/loop.c:1496 [inline]
       lo_ioctl+0x1351/0x1f50 drivers/block/loop.c:1559
       blkdev_ioctl+0x57f/0x6a0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&q->q_usage_counter(io)#19){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       bio_queue_enter block/blk.h:75 [inline]
       blk_mq_submit_bio+0x1536/0x2390 block/blk-mq.c:3090
       __submit_bio+0x2c6/0x560 block/blk-core.c:629
       __submit_bio_noacct_mq block/blk-core.c:710 [inline]
       submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:739
       __block_write_full_folio+0x8b1/0xed0 fs/buffer.c:1904
       write_cache_pages+0xd2/0x230 mm/page-writeback.c:2665
       blkdev_writepages+0xa9/0x100 block/fops.c:433
       do_writepages+0x361/0x880 mm/page-writeback.c:2708
       __writeback_single_inode+0x14f/0x10d0 fs/fs-writeback.c:1680
       writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976
       __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2047
       wb_writeback+0x427/0xb80 fs/fs-writeback.c:2158
       wb_check_background_flush fs/fs-writeback.c:2228 [inline]
       wb_do_writeback fs/fs-writeback.c:2316 [inline]
       wb_workfn+0xc4b/0x1080 fs/fs-writeback.c:2343
       process_one_work kernel/workqueue.c:3236 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3317
       worker_thread+0x870/0xd30 kernel/workqueue.c:3398
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       touch_work_lockdep_map kernel/workqueue.c:3920 [inline]
       start_flush_work kernel/workqueue.c:4174 [inline]
       __flush_work+0x739/0xc60 kernel/workqueue.c:4206
       flush_work kernel/workqueue.c:4263 [inline]
       flush_delayed_work+0x169/0x1c0 kernel/workqueue.c:4285
       wb_shutdown+0x186/0x1e0 mm/backing-dev.c:575
       bdi_unregister+0x19a/0x5d0 mm/backing-dev.c:1158
       del_gendisk+0x400/0x920 block/genhd.c:707
       sd_remove+0x8d/0x110 drivers/scsi/sd.c:4072
       device_remove drivers/base/dd.c:569 [inline]
       __device_release_driver drivers/base/dd.c:1273 [inline]
       device_release_driver_internal+0x505/0x7c0 drivers/base/dd.c:1296
       bus_remove_device+0x34f/0x420 drivers/base/bus.c:576
       device_del+0x57a/0x9b0 drivers/base/core.c:3854
       __scsi_remove_device+0x1ad/0x3c0 drivers/scsi/scsi_sysfs.c:1499
       scsi_forget_host+0xcf/0x110 drivers/scsi/scsi_scan.c:2068
       scsi_remove_host+0x1dd/0x770 drivers/scsi/hosts.c:181
       quiesce_and_remove_host drivers/usb/storage/usb.c:949 [inline]
       usb_stor_disconnect+0x14e/0x1f0 drivers/usb/storage/usb.c:1178
       usb_unbind_interface+0x25d/0x940 drivers/usb/core/driver.c:458
       device_remove drivers/base/dd.c:569 [inline]
       __device_release_driver drivers/base/dd.c:1273 [inline]
       device_release_driver_internal+0x505/0x7c0 drivers/base/dd.c:1296
       bus_remove_device+0x34f/0x420 drivers/base/bus.c:576
       device_del+0x57a/0x9b0 drivers/base/core.c:3854
       usb_disable_device+0x3bf/0x850 drivers/usb/core/message.c:1418
       usb_disconnect+0x340/0x950 drivers/usb/core/hub.c:2304
       hub_port_connect drivers/usb/core/hub.c:5363 [inline]
       hub_port_connect_change drivers/usb/core/hub.c:5663 [inline]
       port_event drivers/usb/core/hub.c:5823 [inline]
       hub_event+0x1ebc/0x5150 drivers/usb/core/hub.c:5905
       process_one_work kernel/workqueue.c:3236 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3317
       worker_thread+0x870/0xd30 kernel/workqueue.c:3398
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

Chain exists of:
  (work_completion)(&(&wb->dwork)->work) --> &q->limits_lock --> &q->q_usage_counter(queue)#56

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&q->q_usage_counter(queue)#56);
                               lock(&q->limits_lock);
                               lock(&q->q_usage_counter(queue)#56);
  lock((work_completion)(&(&wb->dwork)->work));

 *** DEADLOCK ***

9 locks held by kworker/0:7/5892:
 #0: ffff8880212d9548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff8880212d9548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc90003357d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc90003357d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: ffff888028878190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1014 [inline]
 #2: ffff888028878190 (&dev->mutex){....}-{4:4}, at: hub_event+0x1fe/0x5150 drivers/usb/core/hub.c:5851
 #3: ffff8880619b9190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1014 [inline]
 #3: ffff8880619b9190 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x103/0x950 drivers/usb/core/hub.c:2295
 #4: ffff888020ede160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1014 [inline]
 #4: ffff888020ede160 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
 #4: ffff888020ede160 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xce/0x7c0 drivers/base/dd.c:1293
 #5: ffff888057dfc0e0 (&shost->scan_mutex){+.+.}-{4:4}, at: scsi_remove_host+0x34/0x770 drivers/scsi/hosts.c:169
 #6: ffff88801187c378 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1014 [inline]
 #6: ffff88801187c378 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
 #6: ffff88801187c378 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xce/0x7c0 drivers/base/dd.c:1293
 #7: ffff88802865a800 (&q->q_usage_counter(queue)#56){++++}-{0:0}, at: sd_remove+0x8d/0x110 drivers/scsi/sd.c:4072
 #8: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #8: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #8: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4148 [inline]
 #8: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xe9/0xc60 kernel/workqueue.c:4206

stack backtrace:
CPU: 0 UID: 0 PID: 5892 Comm: kworker/0:7 Not tainted 6.13.0-rc7-syzkaller-00043-g619f0b6fad52 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 touch_work_lockdep_map kernel/workqueue.c:3920 [inline]
 start_flush_work kernel/workqueue.c:4174 [inline]
 __flush_work+0x739/0xc60 kernel/workqueue.c:4206
 flush_work kernel/workqueue.c:4263 [inline]
 flush_delayed_work+0x169/0x1c0 kernel/workqueue.c:4285
 wb_shutdown+0x186/0x1e0 mm/backing-dev.c:575
 bdi_unregister+0x19a/0x5d0 mm/backing-dev.c:1158
 del_gendisk+0x400/0x920 block/genhd.c:707
 sd_remove+0x8d/0x110 drivers/scsi/sd.c:4072
 device_remove drivers/base/dd.c:569 [inline]
 __device_release_driver drivers/base/dd.c:1273 [inline]
 device_release_driver_internal+0x505/0x7c0 drivers/base/dd.c:1296
 bus_remove_device+0x34f/0x420 drivers/base/bus.c:576
 device_del+0x57a/0x9b0 drivers/base/core.c:3854
 __scsi_remove_device+0x1ad/0x3c0 drivers/scsi/scsi_sysfs.c:1499
 scsi_forget_host+0xcf/0x110 drivers/scsi/scsi_scan.c:2068
 scsi_remove_host+0x1dd/0x770 drivers/scsi/hosts.c:181
 quiesce_and_remove_host drivers/usb/storage/usb.c:949 [inline]
 usb_stor_disconnect+0x14e/0x1f0 drivers/usb/storage/usb.c:1178
 usb_unbind_interface+0x25d/0x940 drivers/usb/core/driver.c:458
 device_remove drivers/base/dd.c:569 [inline]
 __device_release_driver drivers/base/dd.c:1273 [inline]
 device_release_driver_internal+0x505/0x7c0 drivers/base/dd.c:1296
 bus_remove_device+0x34f/0x420 drivers/base/bus.c:576
 device_del+0x57a/0x9b0 drivers/base/core.c:3854
 usb_disable_device+0x3bf/0x850 drivers/usb/core/message.c:1418
 usb_disconnect+0x340/0x950 drivers/usb/core/hub.c:2304
 hub_port_connect drivers/usb/core/hub.c:5363 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5663 [inline]
 port_event drivers/usb/core/hub.c:5823 [inline]
 hub_event+0x1ebc/0x5150 drivers/usb/core/hub.c:5905
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>