Hello,
syzbot found the following issue on:
HEAD commit: 9247f4e6573a Linux 6.6.98
git tree: linux-6.6.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=10bfa8f0580000
kernel config:
https://syzkaller.appspot.com/x/.config?x=cfe840f14e117c98
dashboard link:
https://syzkaller.appspot.com/bug?extid=c5216c54f2f6b76f6993
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/3855f6db0ca8/disk-9247f4e6.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/fe3d6afeb3a6/vmlinux-9247f4e6.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/7d8784621ac6/bzImage-9247f4e6.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+c5216c...@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
6.6.98-syzkaller #0 Not tainted
------------------------------------------------------
syz.1.356/7074 is trying to acquire lock:
ffff88814e2c80e0 (&type->s_umount_key#32){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
ffff88814e2c80e0 (&type->s_umount_key#32){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
but task is already holding lock:
ffff888148c9f408 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_flushbuf block/ioctl.c:373 [inline]
ffff888148c9f408 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_common_ioctl+0x814/0x23d0 block/ioctl.c:505
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #5 (&bdev->bd_holder_lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
bd_finish_claiming+0x22f/0x3f0 block/bdev.c:568
blkdev_get_by_dev+0x45c/0x600 block/bdev.c:801
bdev_open_by_dev+0x77/0x100 block/bdev.c:842
setup_bdev_super+0x59/0x660 fs/super.c:1496
mount_bdev+0x1dd/0x2d0 fs/super.c:1640
legacy_get_tree+0xea/0x180 fs/fs_context.c:662
vfs_get_tree+0x8c/0x280 fs/super.c:1764
do_new_mount+0x24b/0xa40 fs/namespace.c:3366
init_mount+0xd2/0x120 fs/init.c:25
do_mount_root+0x97/0x230 init/do_mounts.c:166
mount_root_generic+0x195/0x3c0 init/do_mounts.c:205
prepare_namespace+0xc2/0x100 init/do_mounts.c:489
kernel_init_freeable+0x413/0x570 init/main.c:1566
kernel_init+0x1d/0x1c0 init/main.c:1443
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
-> #4 (bdev_lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
bd_prepare_to_claim+0x1ba/0x480 block/bdev.c:510
truncate_bdev_range+0x4e/0x260 block/bdev.c:105
blkdev_fallocate+0x3ff/0x670 block/fops.c:792
vfs_fallocate+0x58e/0x700 fs/open.c:324
madvise_remove mm/madvise.c:1007 [inline]
madvise_vma_behavior mm/madvise.c:1031 [inline]
madvise_walk_vmas mm/madvise.c:1266 [inline]
do_madvise+0x15fe/0x3710 mm/madvise.c:1446
__do_sys_madvise mm/madvise.c:1459 [inline]
__se_sys_madvise mm/madvise.c:1457 [inline]
__x64_sys_madvise+0xa6/0xc0 mm/madvise.c:1457
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #3 (mapping.invalidate_lock#2){++++}-{3:3}:
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
filemap_invalidate_lock_shared include/linux/fs.h:859 [inline]
filemap_fault+0x5db/0x15a0 mm/filemap.c:3330
__do_fault+0x13b/0x4e0 mm/memory.c:4243
do_read_fault mm/memory.c:4616 [inline]
do_fault mm/memory.c:4753 [inline]
do_pte_missing mm/memory.c:3688 [inline]
handle_pte_fault mm/memory.c:5025 [inline]
__handle_mm_fault mm/memory.c:5166 [inline]
handle_mm_fault+0x3886/0x4920 mm/memory.c:5331
faultin_page mm/gup.c:868 [inline]
__get_user_pages+0x5ea/0x1470 mm/gup.c:1167
populate_vma_page_range+0x2b6/0x370 mm/gup.c:1593
__mm_populate+0x24c/0x380 mm/gup.c:1696
mm_populate include/linux/mm.h:3312 [inline]
vm_mmap_pgoff+0x2e7/0x400 mm/util.c:561
ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1427
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #2 (&mm->mmap_lock){++++}-{3:3}:
down_read_killable+0x50/0x340 kernel/locking/rwsem.c:1543
mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:155
get_mmap_lock_carefully mm/memory.c:5367 [inline]
lock_mm_and_find_vma+0x2a3/0x300 mm/memory.c:5418
do_user_addr_fault+0x36c/0x12e0 arch/x86/mm/fault.c:1345
handle_page_fault arch/x86/mm/fault.c:1465 [inline]
exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
fault_in_readable+0xd0/0x160 mm/gup.c:1904
fault_in_iov_iter_readable+0xbf/0x2e0 lib/iov_iter.c:216
generic_perform_write+0x1f2/0x5b0 mm/filemap.c:4006
ext4_buffered_write_iter+0xcc/0x350 fs/ext4/file.c:299
ext4_file_write_iter+0x1d9/0x1870 fs/ext4/file.c:-1
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x43b/0x940 fs/read_write.c:584
ksys_write+0x147/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #1 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
inode_lock_shared include/linux/fs.h:814 [inline]
ext4_bmap+0x4e/0x260 fs/ext4/inode.c:3139
bmap+0xa6/0xe0 fs/inode.c:1871
jbd2_journal_init_inode+0x87/0x3d0 fs/jbd2/journal.c:1711
ext4_open_inode_journal fs/ext4/super.c:5859 [inline]
ext4_load_journal fs/ext4/super.c:6018 [inline]
ext4_load_and_init_journal+0x315/0x2100 fs/ext4/super.c:4922
__ext4_fill_super fs/ext4/super.c:5398 [inline]
ext4_fill_super+0x415f/0x6620 fs/ext4/super.c:5729
get_tree_bdev+0x3e4/0x510 fs/super.c:1591
vfs_get_tree+0x8c/0x280 fs/super.c:1764
do_new_mount+0x24b/0xa40 fs/namespace.c:3366
init_mount+0xd2/0x120 fs/init.c:25
do_mount_root+0x97/0x230 init/do_mounts.c:166
mount_root_generic+0x195/0x3c0 init/do_mounts.c:205
prepare_namespace+0xc2/0x100 init/do_mounts.c:489
kernel_init_freeable+0x413/0x570 init/main.c:1566
kernel_init+0x1d/0x1c0 init/main.c:1443
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
-> #0 (&type->s_umount_key#32){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
__super_lock fs/super.c:58 [inline]
super_lock+0x167/0x360 fs/super.c:117
super_lock_shared fs/super.c:146 [inline]
super_lock_shared_active fs/super.c:1442 [inline]
fs_bdev_sync+0xa4/0x170 fs/super.c:1477
blkdev_flushbuf block/ioctl.c:375 [inline]
blkdev_common_ioctl+0x880/0x23d0 block/ioctl.c:505
blkdev_ioctl+0x4eb/0x6f0 block/ioctl.c:627
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
other info that might help us debug this:
Chain exists of:
&type->s_umount_key#32 --> bdev_lock --> &bdev->bd_holder_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&bdev->bd_holder_lock);
lock(bdev_lock);
lock(&bdev->bd_holder_lock);
rlock(&type->s_umount_key#32);
*** DEADLOCK ***
1 lock held by syz.1.356/7074:
#0: ffff888148c9f408 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_flushbuf block/ioctl.c:373 [inline]
#0: ffff888148c9f408 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_common_ioctl+0x814/0x23d0 block/ioctl.c:505
stack backtrace:
CPU: 0 PID: 7074 Comm: syz.1.356 Not tainted 6.6.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
__super_lock fs/super.c:58 [inline]
super_lock+0x167/0x360 fs/super.c:117
super_lock_shared fs/super.c:146 [inline]
super_lock_shared_active fs/super.c:1442 [inline]
fs_bdev_sync+0xa4/0x170 fs/super.c:1477
blkdev_flushbuf block/ioctl.c:375 [inline]
blkdev_common_ioctl+0x880/0x23d0 block/ioctl.c:505
blkdev_ioctl+0x4eb/0x6f0 block/ioctl.c:627
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8bac18e929
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:00007f8bacf49038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8bac3b5fa0 RCX: 00007f8bac18e929
RDX: 0000000000000008 RSI: 0000000000001261 RDI: 0000000000000004
RBP: 00007f8bac210ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8bac3b5fa0 R15: 00007fff8b2dd068
</TASK>
---
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