[syzbot] possible deadlock in bd_register_pending_holders (2)

From: syzbot
Date: Wed Nov 24 2021 - 11:00:47 EST

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Hello,

syzbot found the following issue on:

HEAD commit: a90af8f15bdc Merge tag 'libata-5.16-rc2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10575be6b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c3ab72998e7f1a4
dashboard link: https://syzkaller.appspot.com/bug?extid=4b74d06c264d2c1e5af3
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4b74d06c264d2c1e5af3@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
5.16.0-rc1-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/4793 is trying to acquire lock:
ffff88801fc2f118 (&disk->open_mutex){+.+.}-{3:3}, at: bd_register_pending_holders+0x32/0x370 block/holder.c:161

but task is already holding lock:
ffffffff8d8dbf88 (disks_mutex){+.+.}-{3:3}, at: md_alloc+0x32/0xbc0 drivers/md/md.c:5658

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #9 (disks_mutex){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
md_alloc+0x32/0xbc0 drivers/md/md.c:5658
blk_request_module+0x19d/0x1c0 block/genhd.c:690
blkdev_get_no_open+0x37/0x180 block/bdev.c:742
blkdev_get_by_dev+0x84/0xb80 block/bdev.c:806
swsusp_check+0xb0/0x2b0 kernel/power/swap.c:1520
software_resume+0xc8/0x3d0 kernel/power/hibernate.c:979
resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2162 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0xb11/0xe90 fs/read_write.c:590
ksys_write+0x18f/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #8 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
blk_request_module+0x2f/0x1c0 block/genhd.c:687
blkdev_get_no_open+0x37/0x180 block/bdev.c:742
blkdev_get_by_dev+0x84/0xb80 block/bdev.c:806
swsusp_check+0xb0/0x2b0 kernel/power/swap.c:1520
software_resume+0xc8/0x3d0 kernel/power/hibernate.c:979
resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2162 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0xb11/0xe90 fs/read_write.c:590
ksys_write+0x18f/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #7 (system_transition_mutex/1){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
software_resume+0x7a/0x3d0 kernel/power/hibernate.c:934
resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2162 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0xb11/0xe90 fs/read_write.c:590
ksys_write+0x18f/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #6 (&of->mutex){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
kernfs_seq_start+0x50/0x3b0 fs/kernfs/file.c:112
seq_read_iter+0x401/0xdc0 fs/seq_file.c:225
call_read_iter include/linux/fs.h:2156 [inline]
new_sync_read fs/read_write.c:400 [inline]
vfs_read+0xaf9/0xe60 fs/read_write.c:481
ksys_read+0x18f/0x2c0 fs/read_write.c:619
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #5 (&p->lock){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
seq_read_iter+0xb6/0xdc0 fs/seq_file.c:182
call_read_iter include/linux/fs.h:2156 [inline]
generic_file_splice_read+0x482/0x760 fs/splice.c:311
do_splice_to fs/splice.c:796 [inline]
splice_direct_to_actor+0x45f/0xd00 fs/splice.c:870
do_splice_direct+0x291/0x3e0 fs/splice.c:979
do_sendfile+0x6fe/0x1040 fs/read_write.c:1245
__do_sys_sendfile64 fs/read_write.c:1310 [inline]
__se_sys_sendfile64+0x171/0x1d0 fs/read_write.c:1296
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #4 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1810 [inline]
sb_start_write include/linux/fs.h:1880 [inline]
file_start_write include/linux/fs.h:3009 [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+0x1682/0x22d0 drivers/block/loop.c:1897
process_one_work+0x853/0x1140 kernel/workqueue.c:2298
worker_thread+0xac1/0x1320 kernel/workqueue.c:2445
kthread+0x468/0x490 kernel/kthread.c:327
ret_from_fork+0x1f/0x30

-> #3 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
process_one_work+0x827/0x1140 kernel/workqueue.c:2274
worker_thread+0xac1/0x1320 kernel/workqueue.c:2445
kthread+0x468/0x490 kernel/kthread.c:327
ret_from_fork+0x1f/0x30

-> #2 ((wq_completion)loop5){+.+.}-{0:0}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
flush_workqueue+0x18e/0x16b0 kernel/workqueue.c:2818
drain_workqueue+0xc3/0x3a0 kernel/workqueue.c:2983
destroy_workqueue+0x7d/0xed0 kernel/workqueue.c:4420
__loop_clr_fd+0x1ec/0x9b0 drivers/block/loop.c:1124
blkdev_put_whole block/bdev.c:694 [inline]
blkdev_put+0x477/0x7b0 block/bdev.c:956
deactivate_locked_super+0xa7/0xf0 fs/super.c:335
cleanup_mnt+0x462/0x510 fs/namespace.c:1137
task_work_run+0x146/0x1c0 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+0x209/0x220 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300
do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #1 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_killable_nested+0x1a/0x20 kernel/locking/mutex.c:807
lo_open+0x68/0x100 drivers/block/loop.c:1733
blkdev_get_whole+0x8c/0x3d0 block/bdev.c:671
blkdev_get_by_dev+0x298/0xb80 block/bdev.c:826
blkdev_open+0x137/0x2f0 block/fops.c:501
do_dentry_open+0x78b/0x1020 fs/open.c:822
do_open fs/namei.c:3426 [inline]
path_openat+0x2896/0x3660 fs/namei.c:3559
do_filp_open+0x277/0x4f0 fs/namei.c:3586
do_sys_openat2+0x13b/0x500 fs/open.c:1212
do_sys_open fs/open.c:1228 [inline]
__do_sys_open fs/open.c:1236 [inline]
__se_sys_open fs/open.c:1232 [inline]
__x64_sys_open+0x221/0x270 fs/open.c:1232
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (&disk->open_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3063 [inline]
check_prevs_add kernel/locking/lockdep.c:3186 [inline]
validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3801
__lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
bd_register_pending_holders+0x32/0x370 block/holder.c:161
device_add_disk+0x4d4/0xe00 block/genhd.c:485
add_disk include/linux/genhd.h:212 [inline]
md_alloc+0x819/0xbc0 drivers/md/md.c:5717
blk_request_module+0x19d/0x1c0 block/genhd.c:690
blkdev_get_no_open+0x37/0x180 block/bdev.c:742
blkdev_get_by_dev+0x84/0xb80 block/bdev.c:806
swsusp_check+0xb0/0x2b0 kernel/power/swap.c:1520
software_resume+0xc8/0x3d0 kernel/power/hibernate.c:979
resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2162 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0xb11/0xe90 fs/read_write.c:590
ksys_write+0x18f/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
&disk->open_mutex --> major_names_lock --> disks_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(disks_mutex);
lock(major_names_lock);
lock(disks_mutex);
lock(&disk->open_mutex);

*** DEADLOCK ***

7 locks held by syz-executor.3/4793:
#0: ffff88807d658af0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
#1: ffff88807eb10460 (sb_writers#6){.+.+}-{0:0}, at: vfs_write+0x2b5/0xe90 fs/read_write.c:586
#2: ffff88803209ec88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1f3/0x510 fs/kernfs/file.c:287
#3: ffff888015d9c830 (kn->active#624){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x217/0x510 fs/kernfs/file.c:288
#4: ffffffff8c9d5ce8 (system_transition_mutex/1){+.+.}-{3:3}, at: software_resume+0x7a/0x3d0 kernel/power/hibernate.c:934
#5: ffffffff8d1116a8 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 block/genhd.c:687
#6: ffffffff8d8dbf88 (disks_mutex){+.+.}-{3:3}, at: md_alloc+0x32/0xbc0 drivers/md/md.c:5658

stack backtrace:
CPU: 1 PID: 4793 Comm: syz-executor.3 Not tainted 5.16.0-rc1-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+0x1dc/0x2d8 lib/dump_stack.c:106
check_noncircular+0x2f9/0x3b0 kernel/locking/lockdep.c:2143
check_prev_add kernel/locking/lockdep.c:3063 [inline]
check_prevs_add kernel/locking/lockdep.c:3186 [inline]
validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3801
__lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
__mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607
__mutex_lock kernel/locking/mutex.c:740 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
bd_register_pending_holders+0x32/0x370 block/holder.c:161
device_add_disk+0x4d4/0xe00 block/genhd.c:485
add_disk include/linux/genhd.h:212 [inline]
md_alloc+0x819/0xbc0 drivers/md/md.c:5717
blk_request_module+0x19d/0x1c0 block/genhd.c:690
blkdev_get_no_open+0x37/0x180 block/bdev.c:742
blkdev_get_by_dev+0x84/0xb80 block/bdev.c:806
swsusp_check+0xb0/0x2b0 kernel/power/swap.c:1520
software_resume+0xc8/0x3d0 kernel/power/hibernate.c:979
resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2162 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0xb11/0xe90 fs/read_write.c:590
ksys_write+0x18f/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7faf24dbbae9
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:00007faf22331188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007faf24ecef60 RCX: 00007faf24dbbae9
RDX: 000000004000fdef RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007faf24e15f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffedf87dfff R14: 00007faf22331300 R15: 0000000000022000
</TASK>
PM: Image not found (code -5)

---
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Next message: Dmitry Baryshkov: "Re: [PATCH v3 10/13] drm/msm/disp/dpu1: Add DSC support in RM"
Previous message: Pali Rohár: "[PATCH 6/6] PCI: pci-bridge-emul: Set PCI_STATUS_CAP_LIST for PCIe device"
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