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Date: Sat, 29 Apr 2023 10:36:35 -0700
From: syzbot <syzbot+aacb82fca60873422114@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, brauner@...nel.org, jack@...e.com,
jack@...e.cz, linkinjeon@...nel.org, linux-ext4@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
sj1557.seo@...sung.com, syzkaller-bugs@...glegroups.com,
tytso@....edu
Subject: Re: [syzbot] [ext4?] [fat?] possible deadlock in sys_quotactl_fd
syzbot has found a reproducer for the following issue on:
HEAD commit: 14f8db1c0f9a Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=115bdcf8280000
kernel config: https://syzkaller.appspot.com/x/.config?x=a837a8ba7e88bb45
dashboard link: https://syzkaller.appspot.com/bug?extid=aacb82fca60873422114
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1405a2b4280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17bd276fc80000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ad6ce516eed3/disk-14f8db1c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f38c2cc7667/vmlinux-14f8db1c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d795115eee39/Image-14f8db1c.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b9312932adf4/mount_0.gz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aacb82fca60873422114@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
6.3.0-rc7-syzkaller-g14f8db1c0f9a #0 Not tainted
------------------------------------------------------
syz-executor396/5961 is trying to acquire lock:
ffff0000d9e5c0e0 (&type->s_umount_key#29){++++}-{3:3}, at: __do_sys_quotactl_fd fs/quota/quota.c:999 [inline]
ffff0000d9e5c0e0 (&type->s_umount_key#29){++++}-{3:3}, at: __se_sys_quotactl_fd fs/quota/quota.c:972 [inline]
ffff0000d9e5c0e0 (&type->s_umount_key#29){++++}-{3:3}, at: __arm64_sys_quotactl_fd+0x30c/0x4a4 fs/quota/quota.c:972
but task is already holding lock:
ffff0000d9e5c460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:394
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (sb_writers#3){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1477 [inline]
sb_start_write include/linux/fs.h:1552 [inline]
write_mmp_block+0xe4/0xb70 fs/ext4/mmp.c:50
ext4_multi_mount_protect+0x2f8/0x8c8 fs/ext4/mmp.c:343
__ext4_remount fs/ext4/super.c:6543 [inline]
ext4_reconfigure+0x2180/0x2928 fs/ext4/super.c:6642
reconfigure_super+0x328/0x738 fs/super.c:956
do_remount fs/namespace.c:2704 [inline]
path_mount+0xc0c/0xe04 fs/namespace.c:3364
do_mount fs/namespace.c:3385 [inline]
__do_sys_mount fs/namespace.c:3594 [inline]
__se_sys_mount fs/namespace.c:3571 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3571
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
-> #0 (&type->s_umount_key#29){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x238/0x718 kernel/locking/lockdep.c:5669
down_read+0x50/0x6c kernel/locking/rwsem.c:1520
__do_sys_quotactl_fd fs/quota/quota.c:999 [inline]
__se_sys_quotactl_fd fs/quota/quota.c:972 [inline]
__arm64_sys_quotactl_fd+0x30c/0x4a4 fs/quota/quota.c:972
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sb_writers#3);
lock(&type->s_umount_key#29);
lock(sb_writers#3);
lock(&type->s_umount_key#29);
*** DEADLOCK ***
1 lock held by syz-executor396/5961:
#0: ffff0000d9e5c460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:394
stack backtrace:
CPU: 0 PID: 5961 Comm: syz-executor396 Not tainted 6.3.0-rc7-syzkaller-g14f8db1c0f9a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056
check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x238/0x718 kernel/locking/lockdep.c:5669
down_read+0x50/0x6c kernel/locking/rwsem.c:1520
__do_sys_quotactl_fd fs/quota/quota.c:999 [inline]
__se_sys_quotactl_fd fs/quota/quota.c:972 [inline]
__arm64_sys_quotactl_fd+0x30c/0x4a4 fs/quota/quota.c:972
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
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