[syzbot] possible deadlock in ext4_ioctl

From: syzbot
Date: Mon Oct 10 2022 - 03:26:10 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 4c86114194e6 Merge tag 'iomap-6.1-merge-1' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c7311c880000
kernel config: https://syzkaller.appspot.com/x/.config?x=9905c889cc4ad738
dashboard link: https://syzkaller.appspot.com/bug?extid=09fc75e906a761cf8eb3
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.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bf7f1dcd539b/disk-4c861141.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c214481af743/vmlinux-4c861141.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09fc75e906a761cf8eb3@xxxxxxxxxxxxxxxxxxxxxxxxx

loop1: detected capacity change from 0 to 1024
EXT4-fs (loop1): mounted filesystem without journal. Quota mode: writeback.
======================================================
WARNING: possible circular locking dependency detected
6.0.0-syzkaller-06475-g4c86114194e6 #0 Not tainted
------------------------------------------------------
syz-executor.1/28617 is trying to acquire lock:
ffff88803cd070e0 (&ei->i_data_sem/1){+.+.}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
ffff88803cd070e0 (&ei->i_data_sem/1){+.+.}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1417 [inline]
ffff88803cd070e0 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_ioctl+0x4129/0x5510 fs/ext4/ioctl.c:1607

but task is already holding lock:
ffff88803cd048c0 (&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+0x182/0x3c0 kernel/locking/lockdep.c:5666
down_read+0x39/0x50 kernel/locking/rwsem.c:1499
ext4_map_blocks+0x398/0x1cc0 fs/ext4/inode.c:568
ext4_getblk+0x1b9/0x770 fs/ext4/inode.c:858
ext4_bread+0x2a/0x170 fs/ext4/inode.c:914
ext4_quota_write+0x225/0x570 fs/ext4/super.c:7087
write_blk fs/quota/quota_tree.c:64 [inline]
get_free_dqblk+0x357/0x6a0 fs/quota/quota_tree.c:93
do_insert_tree+0x26c/0x1a40 fs/quota/quota_tree.c:300
do_insert_tree+0x693/0x1a40 fs/quota/quota_tree.c:331
dq_insert_tree fs/quota/quota_tree.c:357 [inline]
qtree_write_dquot+0x3b6/0x530 fs/quota/quota_tree.c:376
v2_write_dquot+0x11b/0x190 fs/quota/quota_v2.c:358
dquot_acquire+0x348/0x670 fs/quota/dquot.c:444
ext4_acquire_dquot+0x2e0/0x400 fs/ext4/super.c:6743
dqget+0x999/0xdc0 fs/quota/dquot.c:914
__dquot_initialize+0x291/0xcf0 fs/quota/dquot.c:1492
ext4_mkdir+0x194/0xcf0 fs/ext4/namei.c:2977
vfs_mkdir+0x3b3/0x590 fs/namei.c:4013
do_mkdirat+0x279/0x550 fs/namei.c:4038
__do_sys_mkdirat fs/namei.c:4053 [inline]
__se_sys_mkdirat fs/namei.c:4051 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4051
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+0x182/0x3c0 kernel/locking/lockdep.c:5666
down_read+0x39/0x50 kernel/locking/rwsem.c:1499
v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
dquot_acquire+0x186/0x670 fs/quota/dquot.c:435
ext4_acquire_dquot+0x2e0/0x400 fs/ext4/super.c:6743
dqget+0x999/0xdc0 fs/quota/dquot.c:914
__dquot_initialize+0x291/0xcf0 fs/quota/dquot.c:1492
ext4_create+0xb0/0x560 fs/ext4/namei.c:2794
lookup_open fs/namei.c:3413 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x12d0/0x2df0 fs/namei.c:3688
do_filp_open+0x264/0x4f0 fs/namei.c:3718
do_sys_openat2+0x124/0x4e0 fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_open fs/open.c:1334 [inline]
__se_sys_open fs/open.c:1330 [inline]
__x64_sys_open+0x221/0x270 fs/open.c:1330
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+0x182/0x3c0 kernel/locking/lockdep.c:5666
__mutex_lock_common+0x1bd/0x26e0 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+0x58/0x4e0 fs/quota/dquot.c:479
ext4_write_dquot+0x1e4/0x2b0 fs/ext4/super.c:6727
mark_dquot_dirty fs/quota/dquot.c:346 [inline]
mark_all_dquot_dirty fs/quota/dquot.c:384 [inline]
__dquot_alloc_space+0xa09/0x1030 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:493 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1417 [inline]
ext4_ioctl+0x501f/0x5510 fs/ext4/ioctl.c:1607
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+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:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain+0x18c1/0x6bd0 kernel/locking/lockdep.c:3829
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5053
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5666
down_write_nested+0x9e/0x180 kernel/locking/rwsem.c:1662
swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1417 [inline]
ext4_ioctl+0x4129/0x5510 fs/ext4/ioctl.c:1607
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+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 ***

5 locks held by syz-executor.1/28617:
#0: ffff888077ba8460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
#1: ffff88803cd04a38 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff88803cd04a38 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xdd/0x130 fs/inode.c:1121
#2: ffff88803cd07258 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:385 [inline]
#2: ffff88803cd07258 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1417 [inline]
#2: ffff88803cd07258 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: ext4_ioctl+0x23c6/0x5510 fs/ext4/ioctl.c:1607
#3: ffff88803cd04bd8 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:801 [inline]
#3: ffff88803cd04bd8 (mapping.invalidate_lock){++++}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:402 [inline]
#3: ffff88803cd04bd8 (mapping.invalidate_lock){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1417 [inline]
#3: ffff88803cd04bd8 (mapping.invalidate_lock){++++}-{3:3}, at: ext4_ioctl+0x3e21/0x5510 fs/ext4/ioctl.c:1607
#4: ffff88803cd048c0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 1 PID: 28617 Comm: syz-executor.1 Not tainted 6.0.0-syzkaller-06475-g4c86114194e6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
check_noncircular+0x2cc/0x390 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+0x18c1/0x6bd0 kernel/locking/lockdep.c:3829
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5053
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5666
down_write_nested+0x9e/0x180 kernel/locking/rwsem.c:1662
swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1417 [inline]
ext4_ioctl+0x4129/0x5510 fs/ext4/ioctl.c:1607
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+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f30f208a5a9
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:00007f30f32ea168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f30f21abf80 RCX: 00007f30f208a5a9
RDX: 0000000000000000 RSI: 0000000000006611 RDI: 0000000000000003
RBP: 00007f30f20e5580 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd148b2c6f R14: 00007f30f32ea300 R15: 0000000000022000
</TASK>

---
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