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Subject[syzbot] possible deadlock in ext4_ind_migrate
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Hello,

syzbot found the following issue on:

HEAD commit: a5541c0811a0 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=12802800480000
kernel config: https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=a84e36883956fb0221b4
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4b7702208fb9/disk-a5541c08.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9ec0153ec051/vmlinux-a5541c08.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f8725ad290a/Image-a5541c08.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a84e36883956fb0221b4@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0 Not tainted
------------------------------------------------------
syz-executor.3/8019 is trying to acquire lock:
ffff000118015b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ind_migrate+0xc8/0x318 fs/ext4/migrate.c:624

but task is already holding lock:
ffff000113706d30 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff000113706d30 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_fileattr_set+0x78/0x458 fs/ioctl.c:681

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
inode_lock_shared include/linux/fs.h:766 [inline]
ext4_bmap+0x34/0x1c8 fs/ext4/inode.c:3164
bmap+0x40/0x6c fs/inode.c:1798
jbd2_journal_bmap fs/jbd2/journal.c:977 [inline]
__jbd2_journal_erase fs/jbd2/journal.c:1789 [inline]
jbd2_journal_flush+0x2a8/0x55c fs/jbd2/journal.c:2492
ext4_ioctl_checkpoint fs/ext4/ioctl.c:1081 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1586 [inline]
ext4_ioctl+0x1cb8/0x2378 fs/ext4/ioctl.c:1606
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0xd0/0x140 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
el0_svc+0x58/0x150 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:584

-> #1 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
mutex_lock_io_nested+0x6c/0x88 kernel/locking/mutex.c:833
__jbd2_log_wait_for_space+0xc0/0x330 fs/jbd2/checkpoint.c:110
add_transaction_credits+0x4b4/0x604 fs/jbd2/transaction.c:298
start_this_handle+0x2a0/0x7fc fs/jbd2/transaction.c:422
jbd2__journal_start+0x148/0x1f0 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x124/0x1dc fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_ind_migrate+0xec/0x318 fs/ext4/migrate.c:626
ext4_ioctl_setflags+0x5c0/0x5f0 fs/ext4/ioctl.c:695
ext4_fileattr_set+0x174/0x528 fs/ext4/ioctl.c:1003
vfs_fileattr_set+0x400/0x458 fs/ioctl.c:696
do_vfs_ioctl+0x1374/0x16a4
__do_sys_ioctl fs/ioctl.c:868 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x98/0x140 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
el0_svc+0x58/0x150 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:584

-> #0 (&sbi->s_writepages_rwsem){++++}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
percpu_down_write+0x6c/0x188 kernel/locking/percpu-rwsem.c:227
ext4_ind_migrate+0xc8/0x318 fs/ext4/migrate.c:624
ext4_ioctl_setflags+0x5c0/0x5f0 fs/ext4/ioctl.c:695
ext4_fileattr_set+0x174/0x528 fs/ext4/ioctl.c:1003
vfs_fileattr_set+0x400/0x458 fs/ioctl.c:696
do_vfs_ioctl+0x1374/0x16a4
__do_sys_ioctl fs/ioctl.c:868 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x98/0x140 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
el0_svc+0x58/0x150 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:584

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#8

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&sb->s_type->i_mutex_key#8);
lock(&journal->j_checkpoint_mutex);
lock(&sb->s_type->i_mutex_key#8);
lock(&sbi->s_writepages_rwsem);

*** DEADLOCK ***

2 locks held by syz-executor.3/8019:
#0: ffff000118016460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write_file+0x28/0xd8 fs/namespace.c:437
#1: ffff000113706d30 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff000113706d30 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_fileattr_set+0x78/0x458 fs/ioctl.c:681

stack backtrace:
CPU: 1 PID: 8019 Comm: syz-executor.3 Not tainted 6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call trace:
dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
percpu_down_write+0x6c/0x188 kernel/locking/percpu-rwsem.c:227
ext4_ind_migrate+0xc8/0x318 fs/ext4/migrate.c:624
ext4_ioctl_setflags+0x5c0/0x5f0 fs/ext4/ioctl.c:695
ext4_fileattr_set+0x174/0x528 fs/ext4/ioctl.c:1003
vfs_fileattr_set+0x400/0x458 fs/ioctl.c:696
do_vfs_ioctl+0x1374/0x16a4
__do_sys_ioctl fs/ioctl.c:868 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x98/0x140 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
el0_svc+0x58/0x150 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:584


---
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@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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