syzbot


possible deadlock in ext4_move_extents

Status: auto-obsoleted due to no activity on 2023/10/16 22:21
Reported-by: syzbot+b04c3bde86b95df5b7b3@syzkaller.appspotmail.com
First crash: 392d, last: 317d
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ext4_move_extents 2 291d 380d 0/3 auto-obsoleted due to no activity on 2023/11/11 09:48
upstream possible deadlock in ext4_move_extents ext4 133 392d 562d 0/26 auto-obsoleted due to no activity on 2023/08/22 15:17
linux-6.1 possible deadlock in ext4_move_extents (2) 4 39d 158d 0/3 upstream: reported on 2023/12/14 10:09
linux-5.15 possible deadlock in ext4_move_extents (2) 2 119d 189d 0/3 auto-obsoleted due to no activity on 2024/05/01 17:40

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.120-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/12316 is trying to acquire lock:
ffff888090b7f020 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_move_extents+0x395/0xed0 fs/ext4/move_extent.c:610

but task is already holding lock:
ffff888089543450 (&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:5622
       down_read+0x45/0x2e0 kernel/locking/rwsem.c:1488
       ext4_map_blocks+0x3a6/0x1e30 fs/ext4/inode.c:568
       ext4_getblk+0x19f/0x710 fs/ext4/inode.c:856
       ext4_bread+0x2a/0x170 fs/ext4/inode.c:909
       ext4_quota_write+0x21e/0x580 fs/ext4/super.c:6543
       write_blk fs/quota/quota_tree.c:64 [inline]
       get_free_dqblk+0x3a9/0x800 fs/quota/quota_tree.c:125
       do_insert_tree+0x2b4/0x1c20 fs/quota/quota_tree.c:335
       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:444
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6177
       dqget+0x98b/0xdb0 fs/quota/dquot.c:914
       __dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1492
       ext4_setattr+0x2a0/0x1990 fs/ext4/inode.c:5392
       notify_change+0xd4d/0x1000 fs/attr.c:488
       chown_common+0x592/0x890 fs/open.c:680
       do_fchownat+0x169/0x240 fs/open.c:711
       __do_sys_lchown fs/open.c:736 [inline]
       __se_sys_lchown fs/open.c:734 [inline]
       __x64_sys_lchown+0x81/0x90 fs/open.c:734
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       down_read+0x45/0x2e0 kernel/locking/rwsem.c:1488
       v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:435
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6177
       dqget+0x98b/0xdb0 fs/quota/dquot.c:914
       __dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1492
       ext4_create+0xb1/0x550 fs/ext4/namei.c:2822
       lookup_open fs/namei.c:3392 [inline]
       open_last_lookups fs/namei.c:3462 [inline]
       path_openat+0x12f6/0x2f20 fs/namei.c:3669
       do_filp_open+0x21c/0x460 fs/namei.c:3699
       do_sys_openat2+0x13b/0x500 fs/open.c:1211
       do_sys_open fs/open.c:1227 [inline]
       __do_sys_open fs/open.c:1235 [inline]
       __se_sys_open fs/open.c:1231 [inline]
       __x64_sys_open+0x221/0x270 fs/open.c:1231
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __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:479
       ext4_write_dquot+0x1e8/0x2b0 fs/ext4/super.c:6161
       mark_dquot_dirty fs/quota/dquot.c:346 [inline]
       mark_all_dquot_dirty fs/quota/dquot.c:384 [inline]
       __dquot_alloc_space+0x53a/0xf30 fs/quota/dquot.c:1722
       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:1053 [inline]
       ext4_ioctl+0x4d11/0x5b60 fs/ext4/ioctl.c:1273
       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+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #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+0x1646/0x58b0 kernel/locking/lockdep.c:3787
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       down_write_nested+0xa0/0x180 kernel/locking/rwsem.c:1657
       ext4_move_extents+0x395/0xed0 fs/ext4/move_extent.c:610
       __ext4_ioctl fs/ext4/ioctl.c:987 [inline]
       ext4_ioctl+0x2ff5/0x5b60 fs/ext4/ioctl.c:1273
       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+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

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.5/12316:
 #0: ffff88814b2ea460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:421
 #1: ffff8880895435c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff8880895435c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1041
 #2: ffff888090b7f198 (&sb->s_type->i_mutex_key#9/4){+.+.}-{3:3}, at: ext4_move_extents+0x37a/0xed0 fs/ext4/move_extent.c:603
 #3: ffff888089543450 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 12316 Comm: syz-executor.5 Not tainted 5.15.120-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb 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+0x1646/0x58b0 kernel/locking/lockdep.c:3787
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
 down_write_nested+0xa0/0x180 kernel/locking/rwsem.c:1657
 ext4_move_extents+0x395/0xed0 fs/ext4/move_extent.c:610
 __ext4_ioctl fs/ext4/ioctl.c:987 [inline]
 ext4_ioctl+0x2ff5/0x5b60 fs/ext4/ioctl.c:1273
 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+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7d8008d389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7d7e59c168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7d801ad1f0 RCX: 00007f7d8008d389
RDX: 00000000200001c0 RSI: 00000000c028660f RDI: 0000000000000004
RBP: 00007f7d800d8493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffca2f0062f R14: 00007f7d7e59c300 R15: 0000000000022000
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/08 22:20 linux-5.15.y d54cfc420586 668cb1fa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
2023/06/16 05:25 linux-5.15.y 471e639e59d1 f3921d4d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
2023/04/24 12:37 linux-5.15.y 3299fb36854f fdc18293 .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.