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possible deadlock in ext4_move_extents (3)

Status: upstream: reported on 2024/05/28 19:59
Reported-by: syzbot+5d7cbc53175713e9c434@syzkaller.appspotmail.com
First crash: 21d, last: 21d
▶ ▼ Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ext4_move_extents 2 321d 410d 0/3 auto-obsoleted due to no activity on 2023/11/11 09:48
upstream possible deadlock in ext4_move_extents ext4 133 422d 592d 0/27 auto-obsoleted due to no activity on 2023/08/22 15:17
linux-6.1 possible deadlock in ext4_move_extents (2) 6 9d07h 188d 0/3 upstream: reported on 2023/12/14 10:09
linux-5.15 possible deadlock in ext4_move_extents 3 346d 422d 0/3 auto-obsoleted due to no activity on 2023/10/16 22:21
linux-5.15 possible deadlock in ext4_move_extents (2) 2 149d 218d 0/3 auto-obsoleted due to no activity on 2024/05/01 17:40

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.160-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/18118 is trying to acquire lock:
ffff888054802060 (&ei->i_data_sem
/1){+.+.}-{3:3}, at: ext4_move_extents+0x3a1/0xe80 fs/ext4/move_extent.c:610

but task is already holding lock:
ffff888054800278 (&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:5623
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       ext4_map_blocks+0x9e0/0x1e00 fs/ext4/inode.c:638
       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:6566
       write_blk fs/quota/quota_tree.c:64 [inline]
       find_free_dqentry fs/quota/quota_tree.c:307 [inline]
       do_insert_tree+0xf5a/0x1c20 fs/quota/quota_tree.c:364
       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:472
       ext4_acquire_dquot+0x2eb/0x4a0 fs/ext4/super.c:6192
       dqget+0x74e/0xe30 fs/quota/dquot.c:986
       __dquot_initialize+0x2d9/0xea0 fs/quota/dquot.c:1516
       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:4974
       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+0x2ba/0xb40 fs/namespace.c:3005
       do_mount fs/namespace.c:3348 [inline]
       __do_sys_mount fs/namespace.c:3556 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3533
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
       v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2eb/0x4a0 fs/ext4/super.c:6192
       dqget+0x74e/0xe30 fs/quota/dquot.c:986
       __dquot_initialize+0x2d9/0xea0 fs/quota/dquot.c:1516
       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:4974
       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+0x2ba/0xb40 fs/namespace.c:3005
       do_mount fs/namespace.c:3348 [inline]
       __do_sys_mount fs/namespace.c:3556 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3533
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __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:507
       ext4_write_dquot+0x1fd/0x360 fs/ext4/super.c:6172
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf7/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0xdd8/0x1090 fs/quota/dquot.c:1751
       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+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #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+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       down_write_nested+0x3b/0x60 kernel/locking/rwsem.c:1667
       ext4_move_extents+0x3a1/0xe80 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+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.2/18118:
 #0: ffff88807f562460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:421
 #1: ffff8880548003f0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #1: ffff8880548003f0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1083
 #2: ffff8880548021d8 (&sb->s_type->i_mutex_key#9/4){+.+.}-{3:3}, at: ext4_move_extents+0x386/0xe80 fs/ext4/move_extent.c:603
 #3: ffff888054800278 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 18118 Comm: syz-executor.2 Not tainted 5.15.160-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 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+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 down_write_nested+0x3b/0x60 kernel/locking/rwsem.c:1667
 ext4_move_extents+0x3a1/0xe80 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+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f6df1291ee9
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:00007f6def8050c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6df13c8fa0 RCX: 00007f6df1291ee9
RDX: 0000000020000080 RSI: 00000000c028660f RDI: 0000000000000003
RBP: 00007f6df12de47f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f6df13c8fa0 R15: 00007ffd9d72ab68
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/28 19:58 linux-5.15.y c61bd26ae81a 34889ee3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
* Struck through repros no longer work on HEAD.