possible deadlock in blk_request_module

Status: auto-closed as invalid on 2022/03/06 21:21
Subsystems: block
[Documentation on labels]
Reported-by: syzbot+384fb45e189bf86b6bb9@syzkaller.appspotmail.com
First crash: 1792d, last: 1743d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] possible deadlock in blk_request_module 2 (3) 2021/10/17 11:24
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in blk_request_module (2) 4 6 241d 403d 0/3 auto-obsoleted due to no activity on 2026/03/27 18:48
linux-5.15 possible deadlock in blk_request_module (3) 4 2 111d 134d 0/3 auto-obsoleted due to no activity on 2026/08/04 13:53
upstream possible deadlock in blk_request_module (2) prio:low block 4 9 70d 82d 0/29 upstream: reported on 2026/05/25 20:24
linux-5.15 possible deadlock in blk_request_module 4 6 638d 768d 0/3 auto-obsoleted due to no activity on 2025/02/24 02:18

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.0-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/19066 is trying to acquire lock:
ffffffff8c208948 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:680

but task is already holding lock:
ffffffff8b851a28 (system_transition_mutex/1){+.+.}-{3:3}, at: software_resume.part.0+0x19/0x1f0 kernel/power/hibernate.c:934

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #9 (system_transition_mutex/1){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       software_resume.part.0+0x19/0x1f0 kernel/power/hibernate.c:934
       software_resume kernel/power/hibernate.c:86 [inline]
       resume_store+0x161/0x190 kernel/power/hibernate.c:1181
       kobj_attr_store+0x50/0x80 lib/kobject.c:856
       sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:136
       kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2161 [inline]
       new_sync_write+0x429/0x660 fs/read_write.c:503
       vfs_write+0x7cd/0xae0 fs/read_write.c:590
       ksys_write+0x12d/0x250 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #8 (&of->mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       kernfs_seq_start+0x4b/0x260 fs/kernfs/file.c:112
       seq_read_iter+0x2c7/0x1240 fs/seq_file.c:225
       kernfs_fop_read_iter+0x44f/0x5f0 fs/kernfs/file.c:241
       call_read_iter include/linux/fs.h:2155 [inline]
       new_sync_read+0x421/0x6e0 fs/read_write.c:400
       vfs_read+0x35c/0x600 fs/read_write.c:481
       ksys_read+0x12d/0x250 fs/read_write.c:619
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #7 (&p->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       seq_read_iter+0xdf/0x1240 fs/seq_file.c:182
       call_read_iter include/linux/fs.h:2155 [inline]
       generic_file_splice_read+0x453/0x6d0 fs/splice.c:311
       do_splice_to+0x1bf/0x250 fs/splice.c:796
       splice_direct_to_actor+0x2c2/0x8c0 fs/splice.c:870
       do_splice_direct+0x1b3/0x280 fs/splice.c:979
       do_sendfile+0xaf2/0x1250 fs/read_write.c:1245
       __do_sys_sendfile64 fs/read_write.c:1310 [inline]
       __se_sys_sendfile64 fs/read_write.c:1296 [inline]
       __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1296
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #6 (sb_writers#3){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1809 [inline]
       sb_start_write include/linux/fs.h:1879 [inline]
       file_start_write include/linux/fs.h:3008 [inline]
       lo_write_bvec drivers/block/loop.c:242 [inline]
       lo_write_simple drivers/block/loop.c:265 [inline]
       do_req_filebacked drivers/block/loop.c:494 [inline]
       loop_handle_cmd drivers/block/loop.c:1857 [inline]
       loop_process_work+0x1499/0x1db0 drivers/block/loop.c:1897
       process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298
       worker_thread+0x658/0x11f0 kernel/workqueue.c:2445
       kthread+0x405/0x4f0 kernel/kthread.c:327
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #5 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
       process_one_work+0x921/0x1690 kernel/workqueue.c:2274
       worker_thread+0x658/0x11f0 kernel/workqueue.c:2445
       kthread+0x405/0x4f0 kernel/kthread.c:327
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #4 ((wq_completion)loop1){+.+.}-{0:0}:
       flush_workqueue+0x110/0x15b0 kernel/workqueue.c:2818
       drain_workqueue+0x1a5/0x3c0 kernel/workqueue.c:2983
       destroy_workqueue+0x71/0x800 kernel/workqueue.c:4420
       __loop_clr_fd+0x1de/0x1070 drivers/block/loop.c:1124
       lo_release+0x1ac/0x1f0 drivers/block/loop.c:1761
       blkdev_put_whole block/bdev.c:694 [inline]
       blkdev_put+0x2fb/0x9e0 block/bdev.c:956
       blkdev_close+0x6a/0x80 block/fops.c:515
       __fput+0x286/0x9f0 fs/file_table.c:280
       task_work_run+0xdd/0x1a0 kernel/task_work.c:164
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
       exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207
       __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
       syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
       do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #3 (&lo->lo_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       lo_open+0x75/0x120 drivers/block/loop.c:1733
       blkdev_get_whole+0x99/0x2d0 block/bdev.c:671
       blkdev_get_by_dev.part.0+0x354/0xb50 block/bdev.c:826
       blkdev_get_by_dev+0x6b/0x80 block/bdev.c:859
       blkdev_open+0x154/0x2e0 block/fops.c:501
       do_dentry_open+0x4c8/0x11d0 fs/open.c:822
       do_open fs/namei.c:3426 [inline]
       path_openat+0x1c9a/0x2740 fs/namei.c:3559
       do_filp_open+0x1aa/0x400 fs/namei.c:3586
       do_sys_openat2+0x16d/0x4d0 fs/open.c:1200
       do_sys_open fs/open.c:1216 [inline]
       __do_sys_open fs/open.c:1224 [inline]
       __se_sys_open fs/open.c:1220 [inline]
       __x64_sys_open+0x119/0x1c0 fs/open.c:1220
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #2 (&disk->open_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       bd_register_pending_holders+0x2c/0x470 block/holder.c:161
       device_add_disk+0x752/0xfa0 block/genhd.c:478
       add_disk include/linux/genhd.h:212 [inline]
       md_alloc+0x90c/0x1060 drivers/md/md.c:5717
       md_probe+0x69/0x70 drivers/md/md.c:5745
       blk_request_module+0x111/0x1d0 block/genhd.c:683
       blkdev_get_no_open+0x178/0x1e0 block/bdev.c:742
       blkdev_get_by_dev.part.0+0x22/0xb50 block/bdev.c:806
       blkdev_get_by_dev+0x6b/0x80 block/bdev.c:859
       journal_init_dev fs/reiserfs/journal.c:2614 [inline]
       journal_init+0xb5c/0x6570 fs/reiserfs/journal.c:2775
       reiserfs_fill_super+0xc57/0x2f90 fs/reiserfs/super.c:2028
       mount_bdev+0x34d/0x410 fs/super.c:1368
       legacy_get_tree+0x105/0x220 fs/fs_context.c:610
       vfs_get_tree+0x89/0x2f0 fs/super.c:1498
       do_new_mount fs/namespace.c:2988 [inline]
       path_mount+0x1320/0x1fa0 fs/namespace.c:3318
       do_mount fs/namespace.c:3331 [inline]
       __do_sys_mount fs/namespace.c:3539 [inline]
       __se_sys_mount fs/namespace.c:3516 [inline]
       __x64_sys_mount+0x27f/0x300 fs/namespace.c:3516
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #1 (disks_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       md_alloc+0x37/0x1060 drivers/md/md.c:5658
       md_probe+0x69/0x70 drivers/md/md.c:5745
       blk_request_module+0x111/0x1d0 block/genhd.c:683
       blkdev_get_no_open+0x178/0x1e0 block/bdev.c:742
       blkdev_get_by_dev.part.0+0x22/0xb50 block/bdev.c:806
       blkdev_get_by_dev+0x6b/0x80 block/bdev.c:859
       journal_init_dev fs/reiserfs/journal.c:2614 [inline]
       journal_init+0xb5c/0x6570 fs/reiserfs/journal.c:2775
       reiserfs_fill_super+0xc57/0x2f90 fs/reiserfs/super.c:2028
       mount_bdev+0x34d/0x410 fs/super.c:1368
       legacy_get_tree+0x105/0x220 fs/fs_context.c:610
       vfs_get_tree+0x89/0x2f0 fs/super.c:1498
       do_new_mount fs/namespace.c:2988 [inline]
       path_mount+0x1320/0x1fa0 fs/namespace.c:3318
       do_mount fs/namespace.c:3331 [inline]
       __do_sys_mount fs/namespace.c:3539 [inline]
       __se_sys_mount fs/namespace.c:3516 [inline]
       __x64_sys_mount+0x27f/0x300 fs/namespace.c:3516
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (major_names_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3051 [inline]
       check_prevs_add kernel/locking/lockdep.c:3174 [inline]
       validate_chain kernel/locking/lockdep.c:3789 [inline]
       __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
       lock_acquire kernel/locking/lockdep.c:5625 [inline]
       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
       __mutex_lock_common kernel/locking/mutex.c:607 [inline]
       __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
       blk_request_module+0x25/0x1d0 block/genhd.c:680
       blkdev_get_no_open+0x178/0x1e0 block/bdev.c:742
       blkdev_get_by_dev.part.0+0x22/0xb50 block/bdev.c:806
       blkdev_get_by_dev+0x6b/0x80 block/bdev.c:859
       swsusp_check+0x97/0x2f0 kernel/power/swap.c:1520
       software_resume.part.0+0x102/0x1f0 kernel/power/hibernate.c:979
       software_resume kernel/power/hibernate.c:86 [inline]
       resume_store+0x161/0x190 kernel/power/hibernate.c:1181
       kobj_attr_store+0x50/0x80 lib/kobject.c:856
       sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:136
       kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2161 [inline]
       new_sync_write+0x429/0x660 fs/read_write.c:503
       vfs_write+0x7cd/0xae0 fs/read_write.c:590
       ksys_write+0x12d/0x250 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
  major_names_lock --> &of->mutex --> system_transition_mutex/1

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(system_transition_mutex/1);
                               lock(&of->mutex);
                               lock(system_transition_mutex/1);
  lock(major_names_lock);

 *** DEADLOCK ***

5 locks held by syz-executor.2/19066:
 #0: ffff88801a3b6370 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:990
 #1: ffff88807f3f0460 (sb_writers#6){.+.+}-{0:0}, at: ksys_write+0x12d/0x250 fs/read_write.c:643
 #2: ffff8880795ed088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x287/0x500 fs/kernfs/file.c:287
 #3: ffff8880157d3830 (kn->active#761){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2ab/0x500 fs/kernfs/file.c:288
 #4: ffffffff8b851a28 (system_transition_mutex/1){+.+.}-{3:3}, at: software_resume.part.0+0x19/0x1f0 kernel/power/hibernate.c:934

stack backtrace:
CPU: 1 PID: 19066 Comm: syz-executor.2 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131
 check_prev_add kernel/locking/lockdep.c:3051 [inline]
 check_prevs_add kernel/locking/lockdep.c:3174 [inline]
 validate_chain kernel/locking/lockdep.c:3789 [inline]
 __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
 lock_acquire kernel/locking/lockdep.c:5625 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
 __mutex_lock_common kernel/locking/mutex.c:607 [inline]
 __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740
 blk_request_module+0x25/0x1d0 block/genhd.c:680
 blkdev_get_no_open+0x178/0x1e0 block/bdev.c:742
 blkdev_get_by_dev.part.0+0x22/0xb50 block/bdev.c:806
 blkdev_get_by_dev+0x6b/0x80 block/bdev.c:859
 swsusp_check+0x97/0x2f0 kernel/power/swap.c:1520
 software_resume.part.0+0x102/0x1f0 kernel/power/hibernate.c:979
 software_resume kernel/power/hibernate.c:86 [inline]
 resume_store+0x161/0x190 kernel/power/hibernate.c:1181
 kobj_attr_store+0x50/0x80 lib/kobject.c:856
 sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:136
 kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2161 [inline]
 new_sync_write+0x429/0x660 fs/read_write.c:503
 vfs_write+0x7cd/0xae0 fs/read_write.c:590
 ksys_write+0x12d/0x250 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f9a6ee60ae9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9a6c3d6188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9a6ef73f60 RCX: 00007f9a6ee60ae9
RDX: 000000002000fdef RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007f9a6eebaf25 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffefa10a2bf R14: 00007f9a6c3d6300 R15: 0000000000022000
 </TASK>
PM: Image not found (code -5)

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/11/06 21:20 upstream d4439a1189f9 4c1be0be .config console log report info ci-upstream-kasan-gce-root possible deadlock in blk_request_module
2021/09/19 00:34 upstream 93ff9f13be91 70b76c1d .config console log report info ci-upstream-kasan-gce-root possible deadlock in blk_request_module
* Struck through repros no longer work on HEAD.