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Message-ID: <000000000000c2999305c87573a6@google.com>
Date: Sat, 31 Jul 2021 18:34:22 -0700
From: syzbot <syzbot+79e94c217e36db0be7ff@...kaller.appspotmail.com>
To: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] possible deadlock in seq_read_iter
Hello,
syzbot found the following issue on:
HEAD commit: 7d549995d4e0 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157166b6300000
kernel config: https://syzkaller.appspot.com/x/.config?x=1dee114394f7d2c2
dashboard link: https://syzkaller.appspot.com/bug?extid=79e94c217e36db0be7ff
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
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+79e94c217e36db0be7ff@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc3-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/12264 is trying to acquire lock:
ffff8880359f56a8 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xdf/0x1240 fs/seq_file.c:182
but task is already holding lock:
ffff888011080460 (sb_writers#3){.+.+}-{0:0}, at: __do_sys_sendfile64 fs/read_write.c:1325 [inline]
ffff888011080460 (sb_writers#3){.+.+}-{0:0}, at: __se_sys_sendfile64 fs/read_write.c:1311 [inline]
ffff888011080460 (sb_writers#3){.+.+}-{0:0}, at: __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1311
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (sb_writers#3){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1763 [inline]
sb_start_write include/linux/fs.h:1833 [inline]
file_start_write include/linux/fs.h:3040 [inline]
lo_write_bvec+0x3b6/0x6d0 drivers/block/loop.c:286
lo_write_simple drivers/block/loop.c:309 [inline]
do_req_filebacked drivers/block/loop.c:627 [inline]
loop_handle_cmd drivers/block/loop.c:2138 [inline]
loop_process_work+0xc60/0x24e0 drivers/block/loop.c:2178
process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
-> #6 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x8fc/0x1630 kernel/workqueue.c:2252
worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
-> #5 ((wq_completion)loop2){+.+.}-{0:0}:
flush_workqueue+0x110/0x1600 kernel/workqueue.c:2787
drain_workqueue+0x1a5/0x3c0 kernel/workqueue.c:2952
destroy_workqueue+0x71/0x800 kernel/workqueue.c:4389
__loop_clr_fd+0x1f8/0x1540 drivers/block/loop.c:1304
loop_clr_fd drivers/block/loop.c:1430 [inline]
lo_ioctl+0x3c3/0x1600 drivers/block/loop.c:1786
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:585
block_ioctl+0xf9/0x140 fs/block_dev.c:1602
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:1069 [inline]
__se_sys_ioctl fs/ioctl.c:1055 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
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
-> #4 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
lo_open+0x75/0x120 drivers/block/loop.c:1976
blkdev_get_whole+0xa1/0x420 fs/block_dev.c:1251
blkdev_get_by_dev.part.0+0x30c/0xdd0 fs/block_dev.c:1415
blkdev_get_by_dev fs/block_dev.c:1504 [inline]
blkdev_open+0x295/0x300 fs/block_dev.c:1510
do_dentry_open+0x4c8/0x11d0 fs/open.c:826
do_open fs/namei.c:3374 [inline]
path_openat+0x1c23/0x27f0 fs/namei.c:3507
do_filp_open+0x1aa/0x400 fs/namei.c:3534
do_sys_openat2+0x16d/0x420 fs/open.c:1204
do_sys_open fs/open.c:1220 [inline]
__do_sys_open fs/open.c:1228 [inline]
__se_sys_open fs/open.c:1224 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1224
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
-> #3 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
blkdev_get_by_dev.part.0+0x9d/0xdd0 fs/block_dev.c:1408
blkdev_get_by_dev+0x6b/0x80 fs/block_dev.c:1448
swsusp_check+0x4d/0x270 kernel/power/swap.c:1525
software_resume.part.0+0x102/0x1f0 kernel/power/hibernate.c:977
software_resume kernel/power/hibernate.c:86 [inline]
resume_store+0x161/0x190 kernel/power/hibernate.c:1179
kobj_attr_store+0x50/0x80 lib/kobject.c:856
sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2114 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x75a/0xa40 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
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 (system_transition_mutex/1){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
software_resume.part.0+0x19/0x1f0 kernel/power/hibernate.c:932
software_resume kernel/power/hibernate.c:86 [inline]
resume_store+0x161/0x190 kernel/power/hibernate.c:1179
kobj_attr_store+0x50/0x80 lib/kobject.c:856
sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2114 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x75a/0xa40 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
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 (&of->mutex){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
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:2108 [inline]
new_sync_read+0x41e/0x6e0 fs/read_write.c:415
vfs_read+0x35c/0x570 fs/read_write.c:496
ksys_read+0x12d/0x250 fs/read_write.c:634
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 (&p->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:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
seq_read_iter+0xdf/0x1240 fs/seq_file.c:182
call_read_iter include/linux/fs.h:2108 [inline]
generic_file_splice_read+0x450/0x6c0 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+0x9f0/0x1120 fs/read_write.c:1260
__do_sys_sendfile64 fs/read_write.c:1325 [inline]
__se_sys_sendfile64 fs/read_write.c:1311 [inline]
__x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1311
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:
&p->lock --> (work_completion)(&lo->rootcg_work) --> sb_writers#3
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sb_writers#3);
lock((work_completion)(&lo->rootcg_work));
lock(sb_writers#3);
lock(&p->lock);
*** DEADLOCK ***
1 lock held by syz-executor.3/12264:
#0: ffff888011080460 (sb_writers#3){.+.+}-{0:0}, at: __do_sys_sendfile64 fs/read_write.c:1325 [inline]
#0: ffff888011080460 (sb_writers#3){.+.+}-{0:0}, at: __se_sys_sendfile64 fs/read_write.c:1311 [inline]
#0: ffff888011080460 (sb_writers#3){.+.+}-{0:0}, at: __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1311
stack backtrace:
CPU: 1 PID: 12264 Comm: syz-executor.3 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
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:959 [inline]
__mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
seq_read_iter+0xdf/0x1240 fs/seq_file.c:182
call_read_iter include/linux/fs.h:2108 [inline]
generic_file_splice_read+0x450/0x6c0 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+0x9f0/0x1120 fs/read_write.c:1260
__do_sys_sendfile64 fs/read_write.c:1325 [inline]
__se_sys_sendfile64 fs/read_write.c:1311 [inline]
__x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1311
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: 0033:0x4665e9
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:00007f3779708188 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000004
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000fffffffe R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffff725d56f R14: 00007f3779708300 R15: 0000000000022000
---
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 syzkaller@...glegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
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