syzbot


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: 176d, last: 48d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ext4_move_extents 2 476d 565d 0/3 auto-obsoleted due to no activity on 2023/11/11 09:48
linux-6.1 possible deadlock in ext4_move_extents (3) 1 27d 27d 0/3 upstream: reported on 2024/10/24 22:08
upstream possible deadlock in ext4_move_extents ext4 133 576d 747d 0/28 auto-obsoleted due to no activity on 2023/08/22 15:17
linux-6.1 possible deadlock in ext4_move_extents (2) 6 164d 343d 0/3 auto-obsoleted due to no activity on 2024/09/18 11:30
linux-5.15 possible deadlock in ext4_move_extents 3 501d 577d 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 304d 373d 0/3 auto-obsoleted due to no activity on 2024/05/01 17:40

Sample crash report:
EXT4-fs (loop0): mounted filesystem without journal. Opts: nodelalloc,orlov,auto_da_alloc,,errors=continue. Quota mode: writeback.
ext4 filesystem being mounted at /61/bus supports timestamps until 2038 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
5.15.167-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.243/4599 is trying to acquire lock:
ffff888062905238 (&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:
ffff8880609abe48 (&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_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
       ext4_map_blocks+0x391/0x1c70 fs/ext4/inode.c:597
       ext4_getblk+0x19f/0x710 fs/ext4/inode.c:869
       ext4_bread+0x2a/0x170 fs/ext4/inode.c:922
       ext4_quota_read+0x1a1/0x2c0 fs/ext4/super.c:6520
       read_blk fs/quota/quota_tree.c:55 [inline]
       find_tree_dqentry+0x192/0xb60 fs/quota/quota_tree.c:617
       find_tree_dqentry+0x41a/0xb60 fs/quota/quota_tree.c:635
       find_tree_dqentry+0x41a/0xb60 fs/quota/quota_tree.c:635
       find_tree_dqentry+0x41a/0xb60 fs/quota/quota_tree.c:635
       find_dqentry fs/quota/quota_tree.c:647 [inline]
       qtree_read_dquot+0x13f/0x650 fs/quota/quota_tree.c:667
       v2_read_dquot+0xbe/0x100 fs/quota/quota_v2.c:333
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2eb/0x4a0 fs/ext4/super.c:6192
       dqget+0x762/0xe90 fs/quota/dquot.c:986
       __dquot_initialize+0x45e/0xea0 fs/quota/dquot.c:1515
       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:1398
       legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
       vfs_get_tree+0x88/0x270 fs/super.c:1528
       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+0x762/0xe90 fs/quota/dquot.c:986
       __dquot_initialize+0x2d9/0xea0 fs/quota/dquot.c:1515
       ext4_xattr_set+0x104/0x3d0 fs/ext4/xattr.c:2497
       __vfs_setxattr+0x3e7/0x420 fs/xattr.c:182
       __vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
       vfs_setxattr+0x21d/0x420 fs/xattr.c:303
       do_setxattr fs/xattr.c:588 [inline]
       setxattr+0x27e/0x2e0 fs/xattr.c:611
       path_setxattr+0x1bc/0x2a0 fs/xattr.c:630
       __do_sys_setxattr fs/xattr.c:646 [inline]
       __se_sys_setxattr fs/xattr.c:642 [inline]
       __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:642
       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:1750
       dquot_alloc_space_nodirty include/linux/quotaops.h:297 [inline]
       dquot_alloc_space include/linux/quotaops.h:310 [inline]
       dquot_alloc_block include/linux/quotaops.h:334 [inline]
       ext4_mb_new_blocks+0x12d8/0x4d60 fs/ext4/mballoc.c:5742
       ext4_new_meta_blocks+0x206/0x4f0 fs/ext4/balloc.c:738
       ext4_ext_grow_indepth fs/ext4/extents.c:1323 [inline]
       ext4_ext_create_new_leaf fs/ext4/extents.c:1429 [inline]
       ext4_ext_insert_extent+0xf43/0x4e60 fs/ext4/extents.c:2099
       ext4_split_extent_at+0x80e/0x10f0 fs/ext4/extents.c:3230
       ext4_force_split_extent_at fs/ext4/extents.c:319 [inline]
       ext4_swap_extents+0x14ad/0x2340 fs/ext4/extents.c:5761
       move_extent_per_page+0x18b6/0x3010 fs/ext4/move_extent.c:360
       ext4_move_extents+0x9e2/0xe80 fs/ext4/move_extent.c:674
       __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

-> #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.0.243/4599:
 #0: ffff88807ae16460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:421
 #1: ffff8880609abfc0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #1: ffff8880609abfc0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1118
 #2: ffff8880629053b0 (&sb->s_type->i_mutex_key#9/4){+.+.}-{3:3}, at: ext4_move_extents+0x386/0xe80 fs/ext4/move_extent.c:603
 #3: ffff8880609abe48 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 4599 Comm: syz.0.243 Not tainted 5.15.167-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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: 0033:0x7f20dcf73ff9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f20db3ec038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f20dd12bf80 RCX: 00007f20dcf73ff9
RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000004
RBP: 00007f20dcfe6296 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f20dd12bf80 R15: 00007ffd6605ca28
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/10/04 16:13 linux-5.15.y 3a5928702e71 d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
2024/09/04 10:38 linux-5.15.y fa93fa65db6e 9d47f20a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
2024/07/02 21:32 linux-5.15.y 4878aadf2d15 07f0a0a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
2024/06/25 00:49 linux-5.15.y 4878aadf2d15 215eef4a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_move_extents
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.