[v6.1] possible deadlock in ext4_move_extents

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ca48fc16c493 Linux 6.1.27
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=136d83f2280000
kernel config: https://syzkaller.appspot.com/x/.config?x=47d3bbfdb3b1ddd2
dashboard link: https://syzkaller.appspot.com/bug?extid=140c12a4219e871a0532
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/658765c915fa/disk-ca48fc16.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d69e8a1aff2d/vmlinux-ca48fc16.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0317a9546209/bzImage-ca48fc16.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+140c12...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.1.27-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/21702 is trying to acquire lock:
ffff888080e68c90 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_move_extents+0x379/0xe40 fs/ext4/move_extent.c:610

but task is already holding lock:
ffff888080e68288 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ei->i_data_sem/2){++++}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573
ext4_map_blocks+0x97c/0x1ce0 fs/ext4/inode.c:644
ext4_getblk+0x1eb/0x7c0 fs/ext4/inode.c:864
ext4_bread+0x2a/0x170 fs/ext4/inode.c:920
ext4_quota_write+0x21e/0x570 fs/ext4/super.c:7123
write_blk fs/quota/quota_tree.c:64 [inline]
find_free_dqentry fs/quota/quota_tree.c:312 [inline]
do_insert_tree+0xe16/0x1ae0 fs/quota/quota_tree.c:373
do_insert_tree+0x72a/0x1ae0 fs/quota/quota_tree.c:375
do_insert_tree+0x72a/0x1ae0 fs/quota/quota_tree.c:375
do_insert_tree+0x72a/0x1ae0 fs/quota/quota_tree.c:375
dq_insert_tree fs/quota/quota_tree.c:401 [inline]
qtree_write_dquot+0x3b9/0x530 fs/quota/quota_tree.c:420
v2_write_dquot+0x11c/0x190 fs/quota/quota_v2.c:358
dquot_acquire+0x34d/0x680 fs/quota/dquot.c:444
ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6757
dqget+0x98b/0xdb0 fs/quota/dquot.c:914
__dquot_initialize+0x45e/0xe10 fs/quota/dquot.c:1492
ext4_file_open+0x2cf/0x710 fs/ext4/file.c:893
do_dentry_open+0x7f9/0x10f0 fs/open.c:882
do_open fs/namei.c:3557 [inline]
path_openat+0x2644/0x2e60 fs/namei.c:3714
do_filp_open+0x230/0x480 fs/namei.c:3741
do_sys_openat2+0x13b/0x500 fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_creat fs/open.c:1402 [inline]
__se_sys_creat fs/open.c:1396 [inline]
__x64_sys_creat+0x11f/0x160 fs/open.c:1396
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+0x63/0xcd

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_read+0x39/0x50 kernel/locking/rwsem.c:1520
v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
dquot_acquire+0x188/0x680 fs/quota/dquot.c:435
ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6757
dqget+0x98b/0xdb0 fs/quota/dquot.c:914
__dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1492
ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
ext4_orphan_cleanup+0xb1d/0x13c0 fs/ext4/orphan.c:474
__ext4_fill_super fs/ext4/super.c:5531 [inline]
ext4_fill_super+0x83d1/0x8b20 fs/ext4/super.c:5659
get_tree_bdev+0x3fe/0x620 fs/super.c:1346
vfs_get_tree+0x88/0x270 fs/super.c:1553
do_new_mount+0x28b/0xad0 fs/namespace.c:3040
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3568
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+0x63/0xcd

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
dquot_commit+0x57/0x510 fs/quota/dquot.c:479
ext4_write_dquot+0x1e8/0x2b0 fs/ext4/super.c:6741
mark_dquot_dirty fs/quota/dquot.c:346 [inline]
mark_all_dquot_dirty fs/quota/dquot.c:384 [inline]
__dquot_alloc_space+0x53a/0xf30 fs/quota/dquot.c:1722
dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline]
dquot_alloc_space include/linux/quotaops.h:313 [inline]
swap_inode_boot_loader fs/ext4/ioctl.c:494 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1421 [inline]
ext4_ioctl+0x5539/0x5f70 fs/ext4/ioctl.c:1611
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
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+0x63/0xcd

-> #0 (&ei->i_data_sem/1){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
ext4_move_extents+0x379/0xe40 fs/ext4/move_extent.c:610
__ext4_ioctl fs/ext4/ioctl.c:1355 [inline]
ext4_ioctl+0x3ae7/0x5f70 fs/ext4/ioctl.c:1611
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
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+0x63/0xcd

other info that might help us debug this:

Chain exists of:
&ei->i_data_sem/1 --> &s->s_dquot.dqio_sem --> &ei->i_data_sem/2

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&ei->i_data_sem/2);
lock(&s->s_dquot.dqio_sem);
lock(&ei->i_data_sem/2);
lock(&ei->i_data_sem/1);

*** DEADLOCK ***

4 locks held by syz-executor.4/21702:
#0: ffff88807ea36460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
#1: ffff888080e68400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff888080e68400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1121
#2: ffff888080e68e08 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: ext4_move_extents+0x35e/0xe40 fs/ext4/move_extent.c:603
#3: ffff888080e68288 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 21702 Comm: syz-executor.4 Not tainted 6.1.27-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
ext4_move_extents+0x379/0xe40 fs/ext4/move_extent.c:610
__ext4_ioctl fs/ext4/ioctl.c:1355 [inline]
ext4_ioctl+0x3ae7/0x5f70 fs/ext4/ioctl.c:1611
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
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+0x63/0xcd
RIP: 0033:0x7f095908c169
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:00007f0959e16168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f09591ac050 RCX: 00007f095908c169
RDX: 0000000020000080 RSI: 00000000c028660f RDI: 0000000000000006
RBP: 00007f09590e7ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcaa00805f R14: 00007f0959e16300 R15: 0000000000022000
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.