[v5.15] possible deadlock in bd_register_pending_holders

1 view
Skip to first unread message

syzbot

unread,
May 26, 2023, 10:19:59 AM5/26/23
to syzkaller...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 1fe619a7d252 Linux 5.15.113
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1587d61e280000
kernel config: https://syzkaller.appspot.com/x/.config?x=ab36330fd14820aa
dashboard link: https://syzkaller.appspot.com/bug?extid=ad62b217aacd3fc375b2
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2d1716ac5a07/disk-1fe619a7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9e9e3ef13603/vmlinux-1fe619a7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/810a025eede3/bzImage-1fe619a7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ad62b2...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.113-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/17662 is trying to acquire lock:
ffff8880763a8118 (&disk->open_mutex){+.+.}-{3:3}, at: bd_register_pending_holders+0x33/0x320 block/holder.c:161

but task is already holding lock:
ffffffff8cee7ea8 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1a0 block/genhd.c:681

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
blk_request_module+0x2f/0x1a0 block/genhd.c:681
blkdev_get_no_open+0x39/0x190 block/bdev.c:740
blkdev_get_by_dev+0x89/0xa50 block/bdev.c:804
swsusp_check+0xb1/0x2c0 kernel/power/swap.c:1526
software_resume+0xc6/0x3c0 kernel/power/hibernate.c:977
resume_store+0xe3/0x130 kernel/power/hibernate.c:1179
kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2103 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0xacf/0xe50 fs/read_write.c:594
ksys_write+0x1a2/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #6 (system_transition_mutex/1){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
software_resume+0x7c/0x3c0 kernel/power/hibernate.c:932
resume_store+0xe3/0x130 kernel/power/hibernate.c:1179
kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2103 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0xacf/0xe50 fs/read_write.c:594
ksys_write+0x1a2/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #5 (&of->mutex){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
kernfs_seq_start+0x50/0x3b0 fs/kernfs/file.c:112
seq_read_iter+0x3d0/0xd10 fs/seq_file.c:225
call_read_iter include/linux/fs.h:2097 [inline]
new_sync_read fs/read_write.c:404 [inline]
vfs_read+0xa9f/0xe10 fs/read_write.c:485
ksys_read+0x1a2/0x2c0 fs/read_write.c:623
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #4 (&p->lock){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
seq_read_iter+0xae/0xd10 fs/seq_file.c:182
do_iter_readv_writev+0x594/0x7a0
do_iter_read+0x1ec/0x760 fs/read_write.c:790
lo_read_simple drivers/block/loop.c:392 [inline]
do_req_filebacked drivers/block/loop.c:663 [inline]
loop_handle_cmd drivers/block/loop.c:2234 [inline]
loop_process_work+0x1d18/0x2af0 drivers/block/loop.c:2274
process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2307
worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #3 ((work_completion)(&worker->work)){+.+.}-{0:0}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
process_one_work+0x7f1/0x10c0 kernel/workqueue.c:2283
worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #2 ((wq_completion)loop4){+.+.}-{0:0}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
flush_workqueue+0x170/0x1610 kernel/workqueue.c:2827
drain_workqueue+0xc5/0x390 kernel/workqueue.c:2992
destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4427
__loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1383
blkdev_put_whole block/bdev.c:692 [inline]
blkdev_put+0x455/0x790 block/bdev.c:954
blkdev_close+0x7c/0xa0 block/fops.c:475
__fput+0x3bf/0x890 fs/file_table.c:280
task_work_run+0x129/0x1a0 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:175
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x5d/0x250 kernel/entry/common.c:301
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #1 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_killable_nested+0x17/0x20 kernel/locking/mutex.c:758
lo_open+0x68/0x100 drivers/block/loop.c:2055
blkdev_get_whole+0x94/0x390 block/bdev.c:669
blkdev_get_by_dev+0x2b2/0xa50 block/bdev.c:824
blkdev_open+0x138/0x2d0 block/fops.c:463
do_dentry_open+0x807/0xfb0 fs/open.c:826
do_open fs/namei.c:3538 [inline]
path_openat+0x2702/0x2f20 fs/namei.c:3672
do_filp_open+0x21c/0x460 fs/namei.c:3699
do_sys_openat2+0x13b/0x500 fs/open.c:1211
do_sys_open fs/open.c:1227 [inline]
__do_sys_openat fs/open.c:1243 [inline]
__se_sys_openat fs/open.c:1238 [inline]
__x64_sys_openat+0x243/0x290 fs/open.c:1238
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #0 (&disk->open_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
bd_register_pending_holders+0x33/0x320 block/holder.c:161
device_add_disk+0x526/0xc50 block/genhd.c:484
add_disk include/linux/genhd.h:212 [inline]
brd_alloc+0x4e6/0x720 drivers/block/brd.c:425
blk_request_module+0x181/0x1a0 block/genhd.c:684
blkdev_get_no_open+0x39/0x190 block/bdev.c:740
blkdev_get_by_dev+0x89/0xa50 block/bdev.c:804
swsusp_check+0xb1/0x2c0 kernel/power/swap.c:1526
software_resume+0xc6/0x3c0 kernel/power/hibernate.c:977
resume_store+0xe3/0x130 kernel/power/hibernate.c:1179
kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2103 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0xacf/0xe50 fs/read_write.c:594
ksys_write+0x1a2/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

other info that might help us debug this:

Chain exists of:
&disk->open_mutex --> system_transition_mutex/1 --> major_names_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(major_names_lock);
lock(system_transition_mutex/1);
lock(major_names_lock);
lock(&disk->open_mutex);

*** DEADLOCK ***

6 locks held by syz-executor.0/17662:
#0: ffff88807f2dcd70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x261/0x300 fs/file.c:1073
#1: ffff888025244460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x29a/0xe50 fs/read_write.c:590
#2: ffff88807ef56488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x4f0 fs/kernfs/file.c:287
#3: ffff8880169c4cb8 (kn->active#881){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20b/0x4f0 fs/kernfs/file.c:288
#4: ffffffff8c7d5088 (system_transition_mutex/1){+.+.}-{3:3}, at: software_resume+0x7c/0x3c0 kernel/power/hibernate.c:932
#5: ffffffff8cee7ea8 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1a0 block/genhd.c:681

stack backtrace:
CPU: 0 PID: 17662 Comm: syz-executor.0 Not tainted 5.15.113-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
bd_register_pending_holders+0x33/0x320 block/holder.c:161
device_add_disk+0x526/0xc50 block/genhd.c:484
add_disk include/linux/genhd.h:212 [inline]
brd_alloc+0x4e6/0x720 drivers/block/brd.c:425
blk_request_module+0x181/0x1a0 block/genhd.c:684
blkdev_get_no_open+0x39/0x190 block/bdev.c:740
blkdev_get_by_dev+0x89/0xa50 block/bdev.c:804
swsusp_check+0xb1/0x2c0 kernel/power/swap.c:1526
software_resume+0xc6/0x3c0 kernel/power/hibernate.c:977
resume_store+0xe3/0x130 kernel/power/hibernate.c:1179
kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2103 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0xacf/0xe50 fs/read_write.c:594
ksys_write+0x1a2/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fddcc25e169
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fddca7d0168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fddcc37df80 RCX: 00007fddcc25e169
RDX: 0000000000000012 RSI: 0000000020000040 RDI: 0000000000000009
RBP: 00007fddcc2b9ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc53df44ff R14: 00007fddca7d0300 R15: 0000000000022000
</TASK>
PM: Image not found (code -22)


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

syzbot

unread,
Jan 12, 2024, 3:03:12 PMJan 12
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
Reply all
Reply to author
Forward
0 new messages