From: syzbot <syzbot+fb0ff9bfe34ad282ebd4@syzkaller.appspotmail.com>
To: axboe@kernel.dk, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [syzbot] [block?] possible deadlock in blk_request_module (2)
Date: Mon, 25 May 2026 13:24:24 -0700 [thread overview]
Message-ID: <6a14aff8.050a0220.2385e8.0019.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: c1ecb239fa34 Add linux-next specific files for 20260522
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=136a20ee580000
kernel config: https://syzkaller.appspot.com/x/.config?x=77a9211ff284de54
dashboard link: https://syzkaller.appspot.com/bug?extid=fb0ff9bfe34ad282ebd4
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4cb88c910144/disk-c1ecb239.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4a9bc938cf88/vmlinux-c1ecb239.xz
kernel image: https://storage.googleapis.com/syzbot-assets/684f1e33f264/bzImage-c1ecb239.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fb0ff9bfe34ad282ebd4@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
syz.2.2988/16485 is trying to acquire lock:
ffffffff8e94e518 (major_names_lock){+.+.}-{4:4}, at: blk_probe_dev block/genhd.c:881 [inline]
ffffffff8e94e518 (major_names_lock){+.+.}-{4:4}, at: blk_request_module+0x35/0x2a0 block/genhd.c:897
but task is already holding lock:
ffffffff8e0756d8 (system_transition_mutex){+.+.}-{4:4}, at: software_resume+0x47/0x4c0 kernel/power/hibernate.c:1022
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (system_transition_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
lock_system_sleep+0x49/0x70 kernel/power/main.c:71
disk_store+0xa7/0x500 kernel/power/hibernate.c:1217
kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
iter_file_splice_write+0x9a6/0x10f0 fs/splice.c:736
do_splice_from fs/splice.c:936 [inline]
direct_splice_actor+0x104/0x160 fs/splice.c:1159
splice_direct_to_actor+0x545/0xc80 fs/splice.c:1103
do_splice_direct_actor fs/splice.c:1202 [inline]
do_splice_direct+0x19b/0x2a0 fs/splice.c:1228
do_sendfile+0x547/0x7e0 fs/read_write.c:1372
__do_sys_sendfile64 fs/read_write.c:1433 [inline]
__se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #6 (&of->mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
kernfs_seq_start+0x5c/0x420 fs/kernfs/file.c:172
seq_read_iter+0x3f8/0xe20 fs/seq_file.c:226
new_sync_read fs/read_write.c:493 [inline]
vfs_read+0x58b/0xa80 fs/read_write.c:574
ksys_read+0x156/0x270 fs/read_write.c:717
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #5 (&p->lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
seq_read_iter+0xb8/0xe20 fs/seq_file.c:183
lo_rw_aio+0xc80/0xf00 include/linux/percpu-rwsem.h:-1
do_req_filebacked drivers/block/loop.c:435 [inline]
loop_handle_cmd drivers/block/loop.c:1941 [inline]
loop_process_work+0x92a/0x11b0 drivers/block/loop.c:1976
process_one_work+0x98b/0x1630 kernel/workqueue.c:3318
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #4 ((work_completion)(&worker->work)){+.+.}-{0:0}:
process_one_work+0x8d7/0x1630 kernel/workqueue.c:3294
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #3 ((wq_completion)loop8){+.+.}-{0:0}:
touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:4033
__flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:4075
drain_workqueue+0xd3/0x390 kernel/workqueue.c:4239
__loop_clr_fd drivers/block/loop.c:1130 [inline]
lo_release+0x287/0x8f0 drivers/block/loop.c:1767
bdev_release+0x541/0x660 block/bdev.c:-1
blkdev_release+0x15/0x20 block/fops.c:705
__fput+0x461/0xa70 fs/file_table.c:510
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x70f/0x22c0 kernel/exit.c:1004
do_group_exit+0x21b/0x2d0 kernel/exit.c:1147
get_signal+0x1284/0x1330 kernel/signal.c:3038
arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x33e/0x560 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&disk->open_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
__del_gendisk+0x127/0x980 block/genhd.c:710
del_gendisk+0xe7/0x160 block/genhd.c:823
loop_remove+0x42/0xc0 drivers/block/loop.c:2136
loop_control_remove drivers/block/loop.c:2195 [inline]
loop_control_ioctl+0x4ba/0x5b0 drivers/block/loop.c:2237
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&set->update_nr_hwq_lock){++++}-{4:4}:
down_read+0x97/0x200 kernel/locking/rwsem.c:1568
add_disk_fwnode+0xe7/0x480 block/genhd.c:596
add_disk include/linux/blkdev.h:794 [inline]
loop_add+0x86e/0xb50 drivers/block/loop.c:2108
blk_probe_dev block/genhd.c:884 [inline]
blk_request_module+0x27d/0x2a0 block/genhd.c:-1
blkdev_get_no_open+0x3f/0xe0 block/bdev.c:833
blkdev_open+0x1f5/0x620 block/fops.c:688
do_dentry_open+0x83d/0x13e0 fs/open.c:947
vfs_open+0x3b/0x350 fs/open.c:1052
do_open fs/namei.c:4688 [inline]
path_openat+0x2eea/0x3960 fs/namei.c:4847
do_file_open+0x23e/0x4a0 fs/namei.c:4876
do_sys_openat2+0x115/0x200 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (major_names_lock){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3167 [inline]
check_prevs_add kernel/locking/lockdep.c:3286 [inline]
validate_chain kernel/locking/lockdep.c:3910 [inline]
__lock_acquire+0x15a5/0x2d10 kernel/locking/lockdep.c:5239
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
blk_probe_dev block/genhd.c:881 [inline]
blk_request_module+0x35/0x2a0 block/genhd.c:897
blkdev_get_no_open+0x3f/0xe0 block/bdev.c:833
bdev_file_open_by_dev+0xa0/0x240 block/bdev.c:1054
swsusp_check+0x56/0x490 kernel/power/swap.c:1571
software_resume+0x51/0x4c0 kernel/power/hibernate.c:1023
resume_store+0x333/0x4f0 kernel/power/hibernate.c:1307
kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x629/0xba0 fs/read_write.c:688
ksys_write+0x156/0x270 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 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:
major_names_lock --> &of->mutex --> system_transition_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(system_transition_mutex);
lock(&of->mutex);
lock(system_transition_mutex);
lock(major_names_lock);
*** DEADLOCK ***
5 locks held by syz.2.2988/16485:
#0: ffff88803c6b3528 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1260
#1: ffff8880354b8480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
#1: ffff8880354b8480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:684
#2: ffff88803cf6d878 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
#3: ffff88801e299698 (kn->active#62){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
#3: ffff88801e299698 (kn->active#62){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
#4: ffffffff8e0756d8 (system_transition_mutex){+.+.}-{4:4}, at: software_resume+0x47/0x4c0 kernel/power/hibernate.c:1022
stack backtrace:
CPU: 0 UID: 0 PID: 16485 Comm: syz.2.2988 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2045
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3167 [inline]
check_prevs_add kernel/locking/lockdep.c:3286 [inline]
validate_chain kernel/locking/lockdep.c:3910 [inline]
__lock_acquire+0x15a5/0x2d10 kernel/locking/lockdep.c:5239
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
blk_probe_dev block/genhd.c:881 [inline]
blk_request_module+0x35/0x2a0 block/genhd.c:897
blkdev_get_no_open+0x3f/0xe0 block/bdev.c:833
bdev_file_open_by_dev+0xa0/0x240 block/bdev.c:1054
swsusp_check+0x56/0x490 kernel/power/swap.c:1571
software_resume+0x51/0x4c0 kernel/power/hibernate.c:1023
resume_store+0x333/0x4f0 kernel/power/hibernate.c:1307
kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x629/0xba0 fs/read_write.c:688
ksys_write+0x156/0x270 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f29a11dce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f299f436028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f29a1455fa0 RCX: 00007f29a11dce59
RDX: 0000000000000012 RSI: 0000200000000040 RDI: 0000000000000004
RBP: 00007f29a1272d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f29a1456038 R14: 00007f29a1455fa0 R15: 00007fff13825808
</TASK>
block device autoloading is deprecated and will be removed.
PM: Image not found (code -22)
---
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reply other threads:[~2026-05-25 20:24 UTC|newest]
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