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Date: Wed, 17 Aug 2022 00:02:21 -0700
From: syzbot <syzbot+c8139688c30ecca75857@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
tytso@....edu
Subject: [syzbot] possible deadlock in ext4_writepages
Hello,
syzbot found the following issue on:
HEAD commit: 7ebfc85e2cd7 Merge tag 'net-6.0-rc1' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16fdc2f3080000
kernel config: https://syzkaller.appspot.com/x/.config?x=20bc0b329895d963
dashboard link: https://syzkaller.appspot.com/bug?extid=c8139688c30ecca75857
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, 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+c8139688c30ecca75857@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
5.19.0-syzkaller-13930-g7ebfc85e2cd7 #0 Not tainted
------------------------------------------------------
syz-executor.1/6130 is trying to acquire lock:
ffff88814b25cbd8 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x1e7/0x3be0 fs/ext4/inode.c:2687
but task is already holding lock:
ffff88803dd0ca38 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:771 [inline]
ffff88803dd0ca38 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: ext4_dio_read_iter fs/ext4/file.c:63 [inline]
ffff88803dd0ca38 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: ext4_file_read_iter+0x26b/0x740 fs/ext4/file.c:130
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&sb->s_type->i_mutex_key#7){++++}-{3:3}:
lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5666
down_read+0x39/0x50 kernel/locking/rwsem.c:1499
inode_lock_shared include/linux/fs.h:771 [inline]
ext4_bmap+0x55/0x410 fs/ext4/inode.c:3157
bmap+0xa1/0xd0 fs/inode.c:1799
jbd2_journal_bmap fs/jbd2/journal.c:971 [inline]
__jbd2_journal_erase fs/jbd2/journal.c:1784 [inline]
jbd2_journal_flush+0x5d0/0xca0 fs/jbd2/journal.c:2490
ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1586 [inline]
ext4_ioctl+0x378a/0x55c0 fs/ext4/ioctl.c:1606
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #1 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5666
__mutex_lock_common+0x1de/0x26c0 kernel/locking/mutex.c:603
mutex_lock_io_nested+0x43/0x60 kernel/locking/mutex.c:833
__jbd2_log_wait_for_space+0x22d/0x790 fs/jbd2/checkpoint.c:110
add_transaction_credits+0x936/0xbf0 fs/jbd2/transaction.c:298
start_this_handle+0x758/0x1660 fs/jbd2/transaction.c:422
jbd2__journal_start+0x2ca/0x5b0 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x111/0x1d0 fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_writepages+0x1181/0x3be0 fs/ext4/inode.c:2810
do_writepages+0x3c3/0x690 mm/page-writeback.c:2468
filemap_fdatawrite_wbc+0x11e/0x170 mm/filemap.c:388
__filemap_fdatawrite_range mm/filemap.c:421 [inline]
file_write_and_wait_range+0x1e7/0x2f0 mm/filemap.c:773
ext4_sync_file+0x1b0/0x850 fs/ext4/fsync.c:151
generic_write_sync include/linux/fs.h:2874 [inline]
ext4_buffered_write_iter+0x308/0x3a0 fs/ext4/file.c:277
ext4_file_write_iter+0xabb/0x1ae0
do_iter_write+0x6f0/0xc50 fs/read_write.c:855
iter_file_splice_write+0x830/0xff0 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0xe6/0x1c0 fs/splice.c:931
splice_direct_to_actor+0x4e4/0xc00 fs/splice.c:886
do_splice_direct+0x2a0/0x3f0 fs/splice.c:974
do_sendfile+0x641/0xfd0 fs/read_write.c:1249
__do_sys_sendfile64 fs/read_write.c:1311 [inline]
__se_sys_sendfile64+0xfc/0x1e0 fs/read_write.c:1303
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #0 (&sbi->s_writepages_rwsem){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain+0x1872/0x6600 kernel/locking/lockdep.c:3829
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5053
lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5666
percpu_down_read+0x44/0x190 include/linux/percpu-rwsem.h:51
ext4_writepages+0x1e7/0x3be0 fs/ext4/inode.c:2687
do_writepages+0x3c3/0x690 mm/page-writeback.c:2468
filemap_fdatawrite_wbc+0x11e/0x170 mm/filemap.c:388
__filemap_fdatawrite_range mm/filemap.c:421 [inline]
filemap_write_and_wait_range+0x1c1/0x2c0 mm/filemap.c:673
__iomap_dio_rw+0xb25/0x20e0 fs/iomap/direct-io.c:573
iomap_dio_rw+0x42/0xa0 fs/iomap/direct-io.c:690
ext4_dio_read_iter fs/ext4/file.c:79 [inline]
ext4_file_read_iter+0x595/0x740 fs/ext4/file.c:130
call_read_iter include/linux/fs.h:2186 [inline]
generic_file_splice_read+0x24e/0x650 fs/splice.c:309
do_splice_to fs/splice.c:793 [inline]
splice_direct_to_actor+0x41b/0xc00 fs/splice.c:865
do_splice_direct+0x2a0/0x3f0 fs/splice.c:974
do_sendfile+0x641/0xfd0 fs/read_write.c:1249
__do_sys_sendfile64 fs/read_write.c:1317 [inline]
__se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
other info that might help us debug this:
Chain exists of:
&sbi->s_writepages_rwsem --> &journal->j_checkpoint_mutex --> &sb->s_type->i_mutex_key#7
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sb->s_type->i_mutex_key#7);
lock(&journal->j_checkpoint_mutex);
lock(&sb->s_type->i_mutex_key#7);
lock(&sbi->s_writepages_rwsem);
*** DEADLOCK ***
2 locks held by syz-executor.1/6130:
#0: ffff88814b25a460 (sb_writers#4){.+.+}-{0:0}, at: do_sendfile+0x61c/0xfd0 fs/read_write.c:1248
#1: ffff88803dd0ca38 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:771 [inline]
#1: ffff88803dd0ca38 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: ext4_dio_read_iter fs/ext4/file.c:63 [inline]
#1: ffff88803dd0ca38 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: ext4_file_read_iter+0x26b/0x740 fs/ext4/file.c:130
stack backtrace:
CPU: 1 PID: 6130 Comm: syz-executor.1 Not tainted 5.19.0-syzkaller-13930-g7ebfc85e2cd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2f9/0x3b0 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain+0x1872/0x6600 kernel/locking/lockdep.c:3829
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5053
lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5666
percpu_down_read+0x44/0x190 include/linux/percpu-rwsem.h:51
ext4_writepages+0x1e7/0x3be0 fs/ext4/inode.c:2687
do_writepages+0x3c3/0x690 mm/page-writeback.c:2468
filemap_fdatawrite_wbc+0x11e/0x170 mm/filemap.c:388
__filemap_fdatawrite_range mm/filemap.c:421 [inline]
filemap_write_and_wait_range+0x1c1/0x2c0 mm/filemap.c:673
__iomap_dio_rw+0xb25/0x20e0 fs/iomap/direct-io.c:573
iomap_dio_rw+0x42/0xa0 fs/iomap/direct-io.c:690
ext4_dio_read_iter fs/ext4/file.c:79 [inline]
ext4_file_read_iter+0x595/0x740 fs/ext4/file.c:130
call_read_iter include/linux/fs.h:2186 [inline]
generic_file_splice_read+0x24e/0x650 fs/splice.c:309
do_splice_to fs/splice.c:793 [inline]
splice_direct_to_actor+0x41b/0xc00 fs/splice.c:865
do_splice_direct+0x2a0/0x3f0 fs/splice.c:974
do_sendfile+0x641/0xfd0 fs/read_write.c:1249
__do_sys_sendfile64 fs/read_write.c:1317 [inline]
__se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fce42889279
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fce4395e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fce4299c1f0 RCX: 00007fce42889279
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000003
RBP: 00007fce428e3189 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000010000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffdba263bf R14: 00007fce4395e300 R15: 0000000000022000
</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@...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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