From: syzbot <syzbot+df9d057e38be100ccbbe@syzkaller.appspotmail.com>
To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk
Subject: [syzbot] possible deadlock in deactivate_super
Date: Wed, 30 Mar 2022 10:36:28 -0700 [thread overview]
Message-ID: <00000000000048681f05db72fc45@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: a67ba3cf9551 Add linux-next specific files for 20220330
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10ab1377700000
kernel config: https://syzkaller.appspot.com/x/.config?x=994543c31e941639
dashboard link: https://syzkaller.appspot.com/bug?extid=df9d057e38be100ccbbe
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10b3d027700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=159db307700000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+df9d057e38be100ccbbe@syzkaller.appspotmail.com
RBP: 00007ffc747c2860 R08: 00000000ffffffff R09: 00007ffc747c2640
R10: 0000555555879653 R11: 0000000000000202 R12: 00007ffc747c38d0
R13: 00005555558795f0 R14: 00007ffc747c27d0 R15: 0000000000000001
</TASK>
======================================================
WARNING: possible circular locking dependency detected
5.17.0-next-20220330-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor314/3590 is trying to acquire lock:
ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: flush_workqueue+0x135/0x1440 kernel/workqueue.c:2828
but task is already holding lock:
ffff88801df760e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa5/0xd0 fs/super.c:362
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&type->s_umount_key#32){++++}-{3:3}:
down_read+0x98/0x440 kernel/locking/rwsem.c:1461
iterate_supers+0xdb/0x290 fs/super.c:692
drop_caches_sysctl_handler+0xdb/0x110 fs/drop_caches.c:62
proc_sys_call_handler+0x4a1/0x6e0 fs/proc/proc_sysctl.c:604
call_write_iter include/linux/fs.h:2080 [inline]
do_iter_readv_writev+0x3d1/0x640 fs/read_write.c:726
do_iter_write+0x182/0x700 fs/read_write.c:852
vfs_iter_write+0x70/0xa0 fs/read_write.c:893
iter_file_splice_write+0x723/0xc70 fs/splice.c:689
do_splice_from fs/splice.c:767 [inline]
direct_splice_actor+0x110/0x180 fs/splice.c:936
splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891
do_splice_direct+0x1a7/0x270 fs/splice.c:979
do_sendfile+0xae0/0x1240 fs/read_write.c:1246
__do_sys_sendfile64 fs/read_write.c:1305 [inline]
__se_sys_sendfile64 fs/read_write.c:1297 [inline]
__x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1297
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1728 [inline]
sb_start_write include/linux/fs.h:1798 [inline]
file_start_write include/linux/fs.h:2815 [inline]
kernel_write fs/read_write.c:564 [inline]
kernel_write+0x2ac/0x540 fs/read_write.c:555
p9_fd_write net/9p/trans_fd.c:428 [inline]
p9_write_work+0x25e/0xca0 net/9p/trans_fd.c:479
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
-> #1 ((work_completion)(&m->wq)){+.+.}-{0:0}:
process_one_work+0x905/0x1610 kernel/workqueue.c:2265
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
-> #0 ((wq_completion)events){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3096 [inline]
check_prevs_add kernel/locking/lockdep.c:3219 [inline]
validate_chain kernel/locking/lockdep.c:3834 [inline]
__lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5060
lock_acquire kernel/locking/lockdep.c:5672 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637
flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831
flush_scheduled_work include/linux/workqueue.h:583 [inline]
ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202
generic_shutdown_super+0x14c/0x400 fs/super.c:462
kill_block_super+0x97/0xf0 fs/super.c:1394
deactivate_locked_super+0x94/0x160 fs/super.c:332
deactivate_super+0xad/0xd0 fs/super.c:363
cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:183 [inline]
exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:215
__syscall_exit_to_user_mode_work kernel/entry/common.c:297 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:308
do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)events --> sb_writers#3 --> &type->s_umount_key#32
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&type->s_umount_key#32);
lock(sb_writers#3);
lock(&type->s_umount_key#32);
lock((wq_completion)events);
*** DEADLOCK ***
1 lock held by syz-executor314/3590:
#0: ffff88801df760e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa5/0xd0 fs/super.c:362
stack backtrace:
CPU: 1 PID: 3590 Comm: syz-executor314 Not tainted 5.17.0-next-20220330-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:2176
check_prev_add kernel/locking/lockdep.c:3096 [inline]
check_prevs_add kernel/locking/lockdep.c:3219 [inline]
validate_chain kernel/locking/lockdep.c:3834 [inline]
__lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5060
lock_acquire kernel/locking/lockdep.c:5672 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637
flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831
flush_scheduled_work include/linux/workqueue.h:583 [inline]
ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202
generic_shutdown_super+0x14c/0x400 fs/super.c:462
kill_block_super+0x97/0xf0 fs/super.c:1394
deactivate_locked_super+0x94/0x160 fs/super.c:332
deactivate_super+0xad/0xd0 fs/super.c:363
cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:183 [inline]
exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:215
__syscall_exit_to_user_mode_work kernel/entry/common.c:297 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:308
do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2437452687
Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc747c27a8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f2437452687
RDX: 00007ffc747c2869 RSI: 000000000000000a RDI: 00007ffc747c2860
RBP: 00007ffc747c2860 R08: 00000000ffffffff R09: 00007ffc747c2640
R10: 0000555555879653 R11: 0000000000000202 R12: 00007ffc747c38d0
R13: 00005555558795f0 R14: 00007ffc747c27d0 R15: 0000000000000001
</TASK>
---
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@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches
reply other threads:[~2022-03-30 17:36 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=00000000000048681f05db72fc45@google.com \
--to=syzbot+df9d057e38be100ccbbe@syzkaller.appspotmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=syzkaller-bugs@googlegroups.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.