syzbot


possible deadlock in ext4_ioctl (2)

Status: auto-obsoleted due to no activity on 2024/05/18 23:21
Reported-by: syzbot+8059debb04099535c1b5@syzkaller.appspotmail.com
First crash: 132d, last: 132d
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ext4_ioctl 2 265d 365d 0/3 auto-obsoleted due to no activity on 2024/01/09 18:17
upstream possible deadlock in ext4_ioctl ext4 44 425d 619d 0/27 auto-obsoleted due to no activity on 2023/08/20 05:40
linux-6.1 possible deadlock in ext4_ioctl (3) 1 4d18h 4d18h 0/3 upstream: reported on 2024/06/15 14:18
linux-5.15 possible deadlock in ext4_ioctl 1 138d 138d 0/3 auto-obsoleted due to no activity on 2024/05/12 20:19

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.77-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/10054 is trying to acquire lock:
ffff88808950e6d8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
ffff88808950e6d8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
ffff88808950e6d8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_ioctl+0x460f/0x5f60 fs/ext4/ioctl.c:1614

but task is already holding lock:
ffff88804bad20a0 (&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_write+0x21e/0x570 fs/ext4/super.c:7135
       write_blk fs/quota/quota_tree.c:64 [inline]
       get_free_dqblk+0x340/0x6c0 fs/quota/quota_tree.c:130
       do_insert_tree+0x299/0x1ae0 fs/quota/quota_tree.c:340
       do_insert_tree+0x72a/0x1ae0 fs/quota/quota_tree.c:375
       do_insert_tree+0x72a/0x1ae0 fs/quota/quota_tree.c:375
       do_insert_tree+0x72a/0x1ae0 fs/quota/quota_tree.c:375
       dq_insert_tree fs/quota/quota_tree.c:401 [inline]
       qtree_write_dquot+0x3b9/0x530 fs/quota/quota_tree.c:420
       v2_write_dquot+0x11c/0x190 fs/quota/quota_v2.c:358
       dquot_acquire+0x34d/0x680 fs/quota/dquot.c:470
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6769
       dqget+0x74e/0xe30 fs/quota/dquot.c:984
       __dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1562
       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+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #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:461
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6769
       dqget+0x74e/0xe30 fs/quota/dquot.c:984
       __dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1562
       ext4_create+0xb1/0x550 fs/ext4/namei.c:2827
       lookup_open fs/namei.c:3484 [inline]
       open_last_lookups fs/namei.c:3552 [inline]
       path_openat+0x12f1/0x2e60 fs/namei.c:3782
       do_filp_open+0x230/0x480 fs/namei.c:3812
       do_sys_openat2+0x13b/0x500 fs/open.c:1318
       do_sys_open fs/open.c:1334 [inline]
       __do_sys_openat fs/open.c:1350 [inline]
       __se_sys_openat fs/open.c:1345 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1345
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #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:505
       ext4_write_dquot+0x1e8/0x2b0 fs/ext4/super.c:6753
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty fs/quota/dquot.c:410 [inline]
       __dquot_alloc_space+0x574/0xf80 fs/quota/dquot.c:1792
       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+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #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
       swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
       ext4_ioctl+0x460f/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+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

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 ***

6 locks held by syz-executor.2/10054:
 #0: ffff88807f11a460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
 #1: ffff88804bad2218 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #1: ffff88804bad2218 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1165
 #2: ffff88808950e850 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:385 [inline]
 #2: ffff88808950e850 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 #2: ffff88808950e850 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: ext4_ioctl+0x25ff/0x5f60 fs/ext4/ioctl.c:1614
 #3: ffff88804bad23b8 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:801 [inline]
 #3: ffff88804bad23b8 (mapping.invalidate_lock){++++}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:402 [inline]
 #3: ffff88804bad23b8 (mapping.invalidate_lock){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 #3: ffff88804bad23b8 (mapping.invalidate_lock){++++}-{3:3}, at: ext4_ioctl+0x42d7/0x5f60 fs/ext4/ioctl.c:1614
 #4: ffff88807f11e990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f51/0x21b0 fs/jbd2/transaction.c:463
 #5: ffff88804bad20a0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 10054 Comm: syz-executor.2 Not tainted 6.1.77-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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
 swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
 __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 ext4_ioctl+0x460f/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+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fee2487dda9
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:00007fee255d70c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fee249ac120 RCX: 00007fee2487dda9
RDX: 0000000000000000 RSI: 0000000000006611 RDI: 0000000000000009
RBP: 00007fee248ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fee249ac120 R15: 00007fff3b3d1438
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/02/08 23:20 linux-6.1.y f1bb70486c9c 7f07e9b0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_ioctl
* Struck through repros no longer work on HEAD.