syzbot


possible deadlock in swap_inode_boot_loader

Status: upstream: reported on 2025/05/22 04:57
Reported-by: syzbot+7b8dd3f7763aaebe989d@syzkaller.appspotmail.com
First crash: 101d, last: 1d13h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in swap_inode_boot_loader origin:lts-only 4 syz error 3 42d 116d 0/3 upstream: reported syz repro on 2025/05/06 21:29

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.960/7317 is trying to acquire lock:
ffff888071723eb8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: swap_inode_boot_loader+0x529/0x1100 fs/ext4/ioctl.c:426

but task is already holding lock:
ffff8880555920a0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40 fs/ext4/move_extent.c:-1

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ei->i_data_sem/2){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       ext4_map_blocks+0x316/0x1b60 fs/ext4/inode.c:604
       ext4_getblk+0x1ab/0x6d0 fs/ext4/inode.c:890
       ext4_bread+0x26/0x170 fs/ext4/inode.c:946
       ext4_quota_write+0x230/0x570 fs/ext4/super.c:7203
       write_blk fs/quota/quota_tree.c:70 [inline]
       get_free_dqblk+0x312/0x660 fs/quota/quota_tree.c:136
       do_insert_tree+0x22b/0x1040 fs/quota/quota_tree.c:347
       do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402
       dq_insert_tree fs/quota/quota_tree.c:432 [inline]
       qtree_write_dquot+0x48d/0x5b0 fs/quota/quota_tree.c:451
       v2_write_dquot+0x108/0x190 fs/quota/quota_v2.c:361
       dquot_acquire+0x2d5/0x520 fs/quota/dquot.c:472
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6812
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x328/0xcb0 fs/quota/dquot.c:1517
       ext4_setattr+0x2ba/0x19f0 fs/ext4/inode.c:5479
       notify_change+0xc74/0xf40 fs/attr.c:499
       chown_common+0x486/0x620 fs/open.c:736
       do_fchownat+0x164/0x270 fs/open.c:767
       __do_sys_fchownat fs/open.c:782 [inline]
       __se_sys_fchownat fs/open.c:779 [inline]
       __x64_sys_fchownat+0xb1/0xc0 fs/open.c:779
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:335
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6812
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3b6/0xcb0 fs/quota/dquot.c:1517
       ext4_unlink+0x143/0x600 fs/ext4/namei.c:3363
       vfs_unlink+0x385/0x600 fs/namei.c:4322
       do_unlinkat+0x324/0x560 fs/namei.c:4390
       __do_sys_unlinkat fs/namei.c:4433 [inline]
       __se_sys_unlinkat fs/namei.c:4426 [inline]
       __x64_sys_unlinkat+0xd1/0xe0 fs/namei.c:4426
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6792
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0x5fc/0xe60 fs/quota/dquot.c:1752
       dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline]
       dquot_alloc_space+0x1e/0x50 include/linux/quotaops.h:313
       swap_inode_boot_loader+0xe90/0x1100 fs/ext4/ioctl.c:494
       __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
       ext4_ioctl+0x1bd0/0x3dd0 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 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 kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
       swap_inode_boot_loader+0x529/0x1100 fs/ext4/ioctl.c:426
       __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
       ext4_ioctl+0x1bd0/0x3dd0 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 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 ***

5 locks held by syz.2.960/7317:
 #0: ffff88807a520460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:437
 #1: ffff888055592218 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888055592218 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xd5/0x150 fs/inode.c:1208
 #2: ffff888071724030 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: swap_inode_boot_loader+0x70/0x1100 fs/ext4/ioctl.c:385
 #3: ffff8880717241d0 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:803 [inline]
 #3: ffff8880717241d0 (mapping.invalidate_lock){++++}-{3:3}, at: swap_inode_boot_loader+0x37f/0x1100 fs/ext4/ioctl.c:402
 #4: ffff8880555920a0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40 fs/ext4/move_extent.c:-1

stack backtrace:
CPU: 0 PID: 7317 Comm: syz.2.960 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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 kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
 swap_inode_boot_loader+0x529/0x1100 fs/ext4/ioctl.c:426
 __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 ext4_ioctl+0x1bd0/0x3dd0 fs/ext4/ioctl.c:1614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ffb7d38ebe9
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:00007ffb7e1ed038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffb7d5c5fa0 RCX: 00007ffb7d38ebe9
RDX: 0000000000000000 RSI: 0000000000006611 RDI: 0000000000000004
RBP: 00007ffb7d411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffb7d5c6038 R14: 00007ffb7d5c5fa0 R15: 00007ffd69766988
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/30 00:27 linux-6.1.y f89b6e15694c 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in swap_inode_boot_loader
2025/08/28 10:49 linux-6.1.y 0bc96de781b4 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in swap_inode_boot_loader
2025/08/11 10:58 linux-6.1.y 3594f306da12 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in swap_inode_boot_loader
2025/08/06 17:25 linux-6.1.y 3594f306da12 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in swap_inode_boot_loader
2025/06/15 01:03 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in swap_inode_boot_loader
2025/05/22 04:56 linux-6.1.y 325285d9fc86 0919b50b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in swap_inode_boot_loader
* Struck through repros no longer work on HEAD.