Message-ID: <67450fd4.050a0220.1286eb.0007.GAE@google.com>
Date: Mon, 25 Nov 2024 16:01:24 -0800
From: syzbot <syzbot+91585b36b538053343e4@...kaller.appspotmail.com>
To: axboe@...nel.dk, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [block?] possible deadlock in blk_unregister_queue

Hello,

syzbot found the following issue on:

HEAD commit:    9f16d5e6f220 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15542778580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7393f07275e8e571
dashboard link: https://syzkaller.appspot.com/bug?extid=91585b36b538053343e4
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-9f16d5e6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8a4ab7536099/vmlinux-9f16d5e6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a94d1bc43eff/bzImage-9f16d5e6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+91585b36b538053343e4@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.12.0-syzkaller-09073-g9f16d5e6f220 #0 Not tainted
------------------------------------------------------
kworker/0:0/8 is trying to acquire lock:
ffff88802671fb38 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_unregister_queue+0x125/0x2e0 block/blk-sysfs.c:869

but task is already holding lock:
ffff88802671fbc8 (&q->sysfs_dir_lock){+.+.}-{4:4}, at: blk_unregister_queue+0xdb/0x2e0 block/blk-sysfs.c:860

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&q->sysfs_dir_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       blk_mq_sysfs_unregister_hctxs+0x92/0x2d0 block/blk-mq-sysfs.c:278
       __blk_mq_update_nr_hw_queues+0x93f/0x14e0 block/blk-mq.c:4930
       blk_mq_update_nr_hw_queues+0x2a/0x40 block/blk-mq.c:4985
       nbd_start_device+0x15b/0xd70 drivers/block/nbd.c:1413
       nbd_start_device_ioctl drivers/block/nbd.c:1464 [inline]
       __nbd_ioctl drivers/block/nbd.c:1539 [inline]
       nbd_ioctl+0x21a/0xfd0 drivers/block/nbd.c:1579
       blkdev_ioctl+0x276/0x6d0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&q->q_usage_counter(io)#49){++++}-{0:0}:
       bio_queue_enter block/blk.h:75 [inline]
       blk_mq_submit_bio+0x1fb6/0x24c0 block/blk-mq.c:3092
       __submit_bio+0x384/0x540 block/blk-core.c:629
       __submit_bio_noacct_mq block/blk-core.c:710 [inline]
       submit_bio_noacct_nocheck+0x698/0xd70 block/blk-core.c:739
       submit_bio_noacct+0x93a/0x1e20 block/blk-core.c:868
       submit_bh fs/buffer.c:2819 [inline]
       block_read_full_folio+0x812/0xa50 fs/buffer.c:2446
       filemap_read_folio+0xc6/0x2a0 mm/filemap.c:2366
       filemap_update_page mm/filemap.c:2450 [inline]
       filemap_get_pages+0x155f/0x1be0 mm/filemap.c:2571
       filemap_read+0x3ca/0xd70 mm/filemap.c:2646
       blkdev_read_iter+0x187/0x480 block/fops.c:767
       new_sync_read fs/read_write.c:484 [inline]
       vfs_read+0x87f/0xbe0 fs/read_write.c:565
       ksys_read+0x12b/0x250 fs/read_write.c:708
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (mapping.invalidate_lock#2){++++}-{4:4}
:
       down_read+0x9a/0x330 kernel/locking/rwsem.c:1524
       filemap_invalidate_lock_shared include/linux/fs.h:873 [inline]
       filemap_fault+0x2e0/0x2820 mm/filemap.c:3332
       __do_fault+0x10a/0x490 mm/memory.c:4907
       do_shared_fault mm/memory.c:5386 [inline]
       do_fault mm/memory.c:5460 [inline]
       do_pte_missing+0x1a8/0x3e70 mm/memory.c:3979
       handle_pte_fault mm/memory.c:5801 [inline]
       __handle_mm_fault+0x103c/0x2a40 mm/memory.c:5944
       handle_mm_fault+0x3fa/0xaa0 mm/memory.c:6112
       faultin_page mm/gup.c:1187 [inline]
       __get_user_pages+0x8d9/0x3b50 mm/gup.c:1485
       __get_user_pages_locked mm/gup.c:1751 [inline]
       faultin_page_range+0x24a/0x980 mm/gup.c:1975
       madvise_populate mm/madvise.c:951 [inline]
       do_madvise+0x504/0x770 mm/madvise.c:1681
       __do_sys_madvise mm/madvise.c:1700 [inline]
       __se_sys_madvise mm/madvise.c:1698 [inline]
       __x64_sys_madvise+0xa9/0x110 mm/madvise.c:1698
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&mm->mmap_lock){++++}-{4:4}:
       __might_fault mm/memory.c:6751 [inline]
       __might_fault+0x11b/0x190 mm/memory.c:6744
       _inline_copy_from_user include/linux/uaccess.h:162 [inline]
       _copy_from_user+0x29/0xd0 lib/usercopy.c:18
       copy_from_user include/linux/uaccess.h:212 [inline]
       __blk_trace_setup+0xa8/0x180 kernel/trace/blktrace.c:626
       blk_trace_setup+0x47/0x70 kernel/trace/blktrace.c:648
       sg_ioctl_common drivers/scsi/sg.c:1121 [inline]
       sg_ioctl+0x65e/0x2750 drivers/scsi/sg.c:1163
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&q->debugfs_mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       blk_register_queue+0x13c/0x550 block/blk-sysfs.c:774
       add_disk_fwnode+0x785/0x1300 block/genhd.c:493
       add_disk include/linux/blkdev.h:751 [inline]
       brd_alloc.isra.0+0x5a2/0x840 drivers/block/brd.c:399
       brd_init+0x12b/0x1d0 drivers/block/brd.c:479
       do_one_initcall+0x128/0x700 init/main.c:1266
       do_initcall_level init/main.c:1328 [inline]
       do_initcalls init/main.c:1344 [inline]
       do_basic_setup init/main.c:1363 [inline]
       kernel_init_freeable+0x5c7/0x900 init/main.c:1577
       kernel_init+0x1c/0x2b0 init/main.c:1466
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (&q->sysfs_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       blk_unregister_queue+0x125/0x2e0 block/blk-sysfs.c:869
       del_gendisk+0x2de/0xb20 block/genhd.c:710
       md_kobj_release+0xb2/0x100 drivers/md/md.c:5742
       kobject_cleanup lib/kobject.c:689 [inline]
       kobject_release lib/kobject.c:720 [inline]
       kref_put include/linux/kref.h:65 [inline]
       kobject_put+0x1e4/0x5a0 lib/kobject.c:737
       process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
       process_scheduled_works kernel/workqueue.c:3310 [inline]
       worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 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:
  &q->sysfs_lock --> &q->q_usage_counter(io)#49 --> &q->sysfs_dir_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&q->sysfs_dir_lock);
                               lock(&q->q_usage_counter(io)#49);
                               lock(&q->sysfs_dir_lock);
  lock(&q->sysfs_lock);

 *** DEADLOCK ***

3 locks held by kworker/0:0/8:
 #0: ffff88801c79fd48 ((wq_completion)md_misc){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3204
 #1: ffffc900000b7d80 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3205
 #2: ffff88802671fbc8 (&q->sysfs_dir_lock){+.+.}-{4:4}, at: blk_unregister_queue+0xdb/0x2e0 block/blk-sysfs.c:860

stack backtrace:
CPU: 0 UID: 0 PID: 8 Comm: kworker/0:0 Not tainted 6.12.0-syzkaller-09073-g9f16d5e6f220 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: md_misc mddev_delayed_delete
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 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 kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
 blk_unregister_queue+0x125/0x2e0 block/blk-sysfs.c:869
 del_gendisk+0x2de/0xb20 block/genhd.c:710
 md_kobj_release+0xb2/0x100 drivers/md/md.c:5742
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e4/0x5a0 lib/kobject.c:737
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


---
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