Message-ID: <000000000000441aab0618beadc5@google.com>
Date: Sat, 18 May 2024 11:31:30 -0700
From: syzbot <syzbot+007d621ed59411ae5fd0@...kaller.appspotmail.com>
To: jack@...e.com, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: [syzbot] [ext4?] possible deadlock in wait_transaction_locked

Hello,

syzbot found the following issue on:

HEAD commit:    3c999d1ae3c7 Merge tag 'wq-for-6.10' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134e8ae0980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=60e9f916d152f01c
dashboard link: https://syzkaller.appspot.com/bug?extid=007d621ed59411ae5fd0
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-3c999d1a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f2cbecb7d711/vmlinux-3c999d1a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f89ef5a44a32/bzImage-3c999d1a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+007d621ed59411ae5fd0@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-syzkaller-07726-g3c999d1ae3c7 #0 Not tainted
------------------------------------------------------
kswapd0/111 is trying to acquire lock:
ffff88801dc5c950 (jbd2_handle){++++}-{0:0}, at: wait_transaction_locked+0x188/0x230 fs/jbd2/transaction.c:177

but task is already holding lock:
ffffffff8dd38f00 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1a10 mm/vmscan.c:6782

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
       might_alloc include/linux/sched/mm.h:312 [inline]
       slab_pre_alloc_hook mm/slub.c:3819 [inline]
       slab_alloc_node mm/slub.c:3900 [inline]
       __do_kmalloc_node mm/slub.c:4038 [inline]
       __kmalloc_node+0xbb/0x480 mm/slub.c:4046
       kmalloc_node include/linux/slab.h:648 [inline]
       kvmalloc_node+0x9d/0x1a0 mm/util.c:634
       kvmalloc include/linux/slab.h:766 [inline]
       ext4_xattr_inode_cache_find fs/ext4/xattr.c:1535 [inline]
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1581 [inline]
       ext4_xattr_set_entry+0xdc3/0x3b20 fs/ext4/xattr.c:1718
       ext4_xattr_block_set+0xd07/0x3080 fs/ext4/xattr.c:2037
       ext4_xattr_set_handle+0xf24/0x16d0 fs/ext4/xattr.c:2443
       ext4_xattr_set+0x149/0x380 fs/ext4/xattr.c:2545
       __vfs_setxattr+0x173/0x1e0 fs/xattr.c:200
       __vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:234
       __vfs_setxattr_locked+0x182/0x260 fs/xattr.c:295
       vfs_setxattr+0x146/0x350 fs/xattr.c:321
       do_setxattr+0x146/0x170 fs/xattr.c:629
       setxattr+0x15d/0x180 fs/xattr.c:652
       path_setxattr+0x179/0x1e0 fs/xattr.c:671
       __do_sys_setxattr fs/xattr.c:687 [inline]
       __se_sys_setxattr fs/xattr.c:683 [inline]
       __ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:683
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #1 (&ei->xattr_sem){++++}-{3:3}:
       down_write+0x3a/0x50 kernel/locking/rwsem.c:1579
       ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
       ext4_xattr_set_handle+0x156/0x16d0 fs/ext4/xattr.c:2358
       ext4_set_context+0x400/0x5a0 fs/ext4/crypto.c:202
       set_encryption_policy+0x2cc/0x470 fs/crypto/policy.c:500
       fscrypt_ioctl_set_policy+0x4a2/0x500 fs/crypto/policy.c:553
       __ext4_ioctl+0x2f67/0x4700 fs/ext4/ioctl.c:1520
       ext4_ioctl fs/ext4/ioctl.c:1627 [inline]
       ext4_compat_ioctl+0xca/0x460 fs/ext4/ioctl.c:1703
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #0 (jbd2_handle){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
       wait_transaction_locked+0x192/0x230 fs/jbd2/transaction.c:177
       add_transaction_credits+0x10a/0xb80 fs/jbd2/transaction.c:241
       start_this_handle+0x3a3/0x15e0 fs/jbd2/transaction.c:422
       jbd2__journal_start+0x394/0x6a0 fs/jbd2/transaction.c:520
       __ext4_journal_start_sb+0x358/0x660 fs/ext4/ext4_jbd2.c:112
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_dirty_inode+0xa1/0x130 fs/ext4/inode.c:5939
       __mark_inode_dirty+0x1f0/0xe70 fs/fs-writeback.c:2486
       mark_inode_dirty_sync include/linux/fs.h:2426 [inline]
       iput.part.0+0x5b/0x7f0 fs/inode.c:1764
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x440 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       shrink_kill fs/dcache.c:1048 [inline]
       shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
       prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
       super_cache_scan+0x32a/0x550 fs/super.c:221
       do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0xa87/0x1310 mm/shrinker.c:626
       shrink_one+0x493/0x7c0 mm/vmscan.c:4774
       shrink_many mm/vmscan.c:4835 [inline]
       lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935
       shrink_node mm/vmscan.c:5894 [inline]
       kswapd_shrink_node mm/vmscan.c:6704 [inline]
       balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895
       kswapd+0x5ea/0xbf0 mm/vmscan.c:7164
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

Chain exists of:
  jbd2_handle --> &ei->xattr_sem --> fs_reclaim

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&ei->xattr_sem);
                               lock(fs_reclaim);
  lock(jbd2_handle);

 *** DEADLOCK ***

2 locks held by kswapd0/111:
 #0: ffffffff8dd38f00 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1a10 mm/vmscan.c:6782
 #1: ffff88801dc580e0 (&type->s_umount_key#33){++++}-{3:3}, at: super_trylock_shared fs/super.c:561 [inline]
 #1: ffff88801dc580e0 (&type->s_umount_key#33){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196

stack backtrace:
CPU: 0 PID: 111 Comm: kswapd0 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 wait_transaction_locked+0x192/0x230 fs/jbd2/transaction.c:177
 add_transaction_credits+0x10a/0xb80 fs/jbd2/transaction.c:241
 start_this_handle+0x3a3/0x15e0 fs/jbd2/transaction.c:422
 jbd2__journal_start+0x394/0x6a0 fs/jbd2/transaction.c:520
 __ext4_journal_start_sb+0x358/0x660 fs/ext4/ext4_jbd2.c:112
 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
 ext4_dirty_inode+0xa1/0x130 fs/ext4/inode.c:5939
 __mark_inode_dirty+0x1f0/0xe70 fs/fs-writeback.c:2486
 mark_inode_dirty_sync include/linux/fs.h:2426 [inline]
 iput.part.0+0x5b/0x7f0 fs/inode.c:1764
 iput+0x5c/0x80 fs/inode.c:1757
 dentry_unlink_inode+0x295/0x440 fs/dcache.c:400
 __dentry_kill+0x1d0/0x600 fs/dcache.c:603
 shrink_kill fs/dcache.c:1048 [inline]
 shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
 prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
 super_cache_scan+0x32a/0x550 fs/super.c:221
 do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
 shrink_slab_memcg mm/shrinker.c:548 [inline]
 shrink_slab+0xa87/0x1310 mm/shrinker.c:626
 shrink_one+0x493/0x7c0 mm/vmscan.c:4774
 shrink_many mm/vmscan.c:4835 [inline]
 lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935
 shrink_node mm/vmscan.c:5894 [inline]
 kswapd_shrink_node mm/vmscan.c:6704 [inline]
 balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895
 kswapd+0x5ea/0xbf0 mm/vmscan.c:7164
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


---
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