[v5.15] possible deadlock in ext4_move_extents (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 80529b4968a8 Linux 5.15.138
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1698bc20e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=c431dbb457f792c5
dashboard link: https://syzkaller.appspot.com/bug?extid=9b3915dd430ce8175529
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4fd4b10a6041/disk-80529b49.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/60443f81279e/vmlinux-80529b49.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c7f38af1be13/bzImage-80529b49.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b3915...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.138-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/6494 is trying to acquire lock:
ffff8880744df020 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_move_extents+0x395/0xed0 fs/ext4/move_extent.c:610

but task is already holding lock:
ffff8880744dd238 (&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+0x1db/0x4f0 kernel/locking/lockdep.c:5622
down_read+0x45/0x2e0 kernel/locking/rwsem.c:1488
ext4_map_blocks+0x3a6/0x1e00 fs/ext4/inode.c:568
ext4_getblk+0x19f/0x710 fs/ext4/inode.c:846
ext4_bread+0x2a/0x170 fs/ext4/inode.c:899
ext4_quota_write+0x21e/0x580 fs/ext4/super.c:6546
write_blk fs/quota/quota_tree.c:64 [inline]
get_free_dqblk+0x3a9/0x800 fs/quota/quota_tree.c:125
do_insert_tree+0x2b4/0x1c20 fs/quota/quota_tree.c:335
do_insert_tree+0x6d0/0x1c20 fs/quota/quota_tree.c:366
do_insert_tree+0x6d0/0x1c20 fs/quota/quota_tree.c:366
do_insert_tree+0x6d0/0x1c20 fs/quota/quota_tree.c:366
dq_insert_tree fs/quota/quota_tree.c:392 [inline]
qtree_write_dquot+0x3b9/0x530 fs/quota/quota_tree.c:411
v2_write_dquot+0x11c/0x190 fs/quota/quota_v2.c:358
dquot_acquire+0x34d/0x680 fs/quota/dquot.c:470
ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6180
dqget+0x74e/0xe30 fs/quota/dquot.c:984
__dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1562
ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
ext4_orphan_cleanup+0x9d9/0x1240 fs/ext4/orphan.c:474
ext4_fill_super+0x98de/0xa110 fs/ext4/super.c:4966
mount_bdev+0x2c9/0x3f0 fs/super.c:1387
legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1517
do_new_mount+0x28b/0xae0 fs/namespace.c:2994
do_mount fs/namespace.c:3337 [inline]
__do_sys_mount fs/namespace.c:3545 [inline]
__se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3522
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+0x61/0xcb

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
down_read+0x45/0x2e0 kernel/locking/rwsem.c:1488
v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
dquot_acquire+0x188/0x680 fs/quota/dquot.c:461
ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6180
dqget+0x74e/0xe30 fs/quota/dquot.c:984
__dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1562
ext4_mkdir+0x197/0xce0 fs/ext4/namei.c:3010
vfs_mkdir+0x419/0x640 fs/namei.c:3994
do_mkdirat+0x260/0x520 fs/namei.c:4019
__do_sys_mkdirat fs/namei.c:4034 [inline]
__se_sys_mkdirat fs/namei.c:4032 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4032
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+0x61/0xcb

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
dquot_commit+0x57/0x510 fs/quota/dquot.c:505
ext4_write_dquot+0x1e8/0x2b0 fs/ext4/super.c:6164
mark_dquot_dirty fs/quota/dquot.c:372 [inline]
mark_all_dquot_dirty fs/quota/dquot.c:410 [inline]
__dquot_alloc_space+0x53a/0xf30 fs/quota/dquot.c:1792
dquot_alloc_space_nodirty include/linux/quotaops.h:297 [inline]
dquot_alloc_space include/linux/quotaops.h:310 [inline]
swap_inode_boot_loader fs/ext4/ioctl.c:243 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1056 [inline]
ext4_ioctl+0x4d2f/0x5b80 fs/ext4/ioctl.c:1276
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
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+0x61/0xcb

-> #0 (&ei->i_data_sem/1){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
down_write_nested+0xa0/0x180 kernel/locking/rwsem.c:1657
ext4_move_extents+0x395/0xed0 fs/ext4/move_extent.c:610
__ext4_ioctl fs/ext4/ioctl.c:990 [inline]
ext4_ioctl+0x2fcb/0x5b80 fs/ext4/ioctl.c:1276
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
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+0x61/0xcb

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.5/6494:
#0: ffff88814b294460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:421
#1: ffff8880744dd3b0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
#1: ffff8880744dd3b0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1083
#2: ffff8880744df198 (&sb->s_type->i_mutex_key#9/4){+.+.}-{3:3}, at: ext4_move_extents+0x37a/0xed0 fs/ext4/move_extent.c:603
#3: ffff8880744dd238 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 6494 Comm: syz-executor.5 Not tainted 5.15.138-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
down_write_nested+0xa0/0x180 kernel/locking/rwsem.c:1657
ext4_move_extents+0x395/0xed0 fs/ext4/move_extent.c:610
__ext4_ioctl fs/ext4/ioctl.c:990 [inline]
ext4_ioctl+0x2fcb/0x5b80 fs/ext4/ioctl.c:1276
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
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+0x61/0xcb
RIP: 0033:0x7f4a7a386ae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4a788840c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4a7a4a62c0 RCX: 00007f4a7a386ae9
RDX: 0000000020000140 RSI: 00000000c028660f RDI: 0000000000000009
RBP: 00007f4a7a3d247a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f4a7a4a62c0 R15: 00007fff8390fd48
</TASK>


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[syzbot]

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