syzbot


possible deadlock in ext4_move_extents (2)

Status: upstream: reported on 2023/12/14 10:09
Reported-by: syzbot+a7494644eb0eea478057@syzkaller.appspotmail.com
First crash: 167d, last: 48d
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 300d 389d 0/3 auto-obsoleted due to no activity on 2023/11/11 09:48
upstream possible deadlock in ext4_move_extents ext4 133 401d 571d 0/26 auto-obsoleted due to no activity on 2023/08/22 15:17
linux-5.15 possible deadlock in ext4_move_extents 3 326d 401d 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 128d 198d 0/3 auto-obsoleted due to no activity on 2024/05/01 17:40
linux-5.15 possible deadlock in ext4_move_extents (3) 1 1d05h 1d05h 0/3 upstream: reported on 2024/05/28 19:59

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.85-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/6823 is trying to acquire lock:
ffff8880538aa0a0 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_move_extents+0x3a0/0xe30 fs/ext4/move_extent.c:616

but task is already holding lock:
ffff8880538a8c90 (&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+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       down_read+0xad/0xa30 kernel/locking/rwsem.c:1520
       ext4_map_blocks+0x37a/0x1ca0 fs/ext4/inode.c:574
       ext4_getblk+0x1eb/0x7c0 fs/ext4/inode.c:866
       ext4_bread+0x2a/0x170 fs/ext4/inode.c:922
       ext4_quota_read+0x1a1/0x2c0 fs/ext4/super.c:7089
       read_blk fs/quota/quota_tree.c:55 [inline]
       find_tree_dqentry+0x190/0xc10 fs/quota/quota_tree.c:624
       find_tree_dqentry+0x48a/0xc10 fs/quota/quota_tree.c:640
       find_tree_dqentry+0x48a/0xc10 fs/quota/quota_tree.c:640
       find_tree_dqentry+0x48a/0xc10 fs/quota/quota_tree.c:640
       find_dqentry fs/quota/quota_tree.c:652 [inline]
       qtree_read_dquot+0x13f/0x650 fs/quota/quota_tree.c:672
       v2_read_dquot+0xbe/0x100 fs/quota/quota_v2.c:333
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6769
       dqget+0x74e/0xe30 fs/quota/dquot.c:986
       __dquot_initialize+0x45e/0xea0 fs/quota/dquot.c:1516
       ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xb70/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5533 [inline]
       ext4_fill_super+0x83ff/0x8b50 fs/ext4/super.c:5664
       get_tree_bdev+0x3fe/0x620 fs/super.c:1355
       vfs_get_tree+0x88/0x270 fs/super.c:1562
       do_new_mount+0x2ba/0xb40 fs/namespace.c:3051
       do_mount fs/namespace.c:3394 [inline]
       __do_sys_mount fs/namespace.c:3602 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3579
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       down_read+0xad/0xa30 kernel/locking/rwsem.c:1520
       v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6769
       dqget+0x74e/0xe30 fs/quota/dquot.c:986
       __dquot_initialize+0x45e/0xea0 fs/quota/dquot.c:1516
       ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xb70/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5533 [inline]
       ext4_fill_super+0x83ff/0x8b50 fs/ext4/super.c:5664
       get_tree_bdev+0x3fe/0x620 fs/super.c:1355
       vfs_get_tree+0x88/0x270 fs/super.c:1562
       do_new_mount+0x2ba/0xb40 fs/namespace.c:3051
       do_mount fs/namespace.c:3394 [inline]
       __do_sys_mount fs/namespace.c:3602 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3579
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       dquot_commit+0x57/0x510 fs/quota/dquot.c:507
       ext4_write_dquot+0x1e8/0x2b0 fs/ext4/super.c:6753
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0x1e0/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0xb68/0x10e0 fs/quota/dquot.c:1751
       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:494 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
       ext4_ioctl+0x551e/0x5f60 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ei->i_data_sem/1){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
       ext4_move_extents+0x3a0/0xe30 fs/ext4/move_extent.c:616
       __ext4_ioctl fs/ext4/ioctl.c:1358 [inline]
       ext4_ioctl+0x3a8d/0x5f60 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

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.4/6823:
 #0: ffff88814bd3a460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
 #1: ffff8880538a8e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff8880538a8e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1165
 #2: ffff8880538aa218 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: ext4_move_extents+0x385/0xe30 fs/ext4/move_extent.c:609
 #3: ffff8880538a8c90 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 1 PID: 6823 Comm: syz-executor.4 Not tainted 6.1.85-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
 ext4_move_extents+0x3a0/0xe30 fs/ext4/move_extent.c:616
 __ext4_ioctl fs/ext4/ioctl.c:1358 [inline]
 ext4_ioctl+0x3a8d/0x5f60 fs/ext4/ioctl.c:1614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4b0e07de69
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:00007f4b0ee080c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4b0e1abf80 RCX: 00007f4b0e07de69
RDX: 00000000200000c0 RSI: 00000000c028660f RDI: 0000000000000004
RBP: 00007f4b0e0ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f4b0e1abf80 R15: 00007ffd54f13ef8
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/11 03:16 linux-6.1.y bf1e3b1cb1e0 33b9e058 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_move_extents
2024/03/18 14:43 linux-6.1.y d7543167affd baa80228 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_move_extents
2024/02/15 20:29 linux-6.1.y f1bb70486c9c fd39cf6f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_move_extents
2023/12/14 10:08 linux-6.1.y ba6f5fb46511 3222d10c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_move_extents
* Struck through repros no longer work on HEAD.