syzbot

syz.0.17[5920]: memfd_create() called without MFD_EXEC or MFD_NOEXEC_SEAL set
loop0: detected capacity change from 0 to 128
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/5920 is trying to acquire lock:
ffffffff8ca648e8 (bdev_lock){+.+.}-{3:3}, at: bd_prepare_to_claim+0x1ba/0x480 block/bdev.c:527

but task is already holding lock:
ffff888148c8a040 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:849 [inline]
ffff888148c8a040 (mapping.invalidate_lock){++++}-{3:3}, at: blkdev_fallocate+0x22b/0x6a0 block/fops.c:789

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (mapping.invalidate_lock){++++}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       filemap_invalidate_lock include/linux/fs.h:849 [inline]
       set_blocksize+0x249/0x4b0 block/bdev.c:161
       sb_set_blocksize block/bdev.c:178 [inline]
       sb_min_blocksize+0xbe/0x190 block/bdev.c:194
       ext4_load_super fs/ext4/super.c:5042 [inline]
       __ext4_fill_super fs/ext4/super.c:5251 [inline]
       ext4_fill_super+0x6df/0x66c0 fs/ext4/super.c:5724
       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:3386
       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:1578
       kernel_init+0x1d/0x1c0 init/main.c:1455
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #3 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:804 [inline]
       set_blocksize+0x201/0x4b0 block/bdev.c:160
       sb_set_blocksize block/bdev.c:178 [inline]
       sb_min_blocksize+0xbe/0x190 block/bdev.c:194
       fat_fill_super+0x1b21/0x4c00 fs/fat/inode.c:1644
       mount_bdev+0x22b/0x2d0 fs/super.c:1643
       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:3386
       do_mount fs/namespace.c:3726 [inline]
       __do_sys_mount fs/namespace.c:3935 [inline]
       __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
       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 (&type->s_umount_key#56){++++}-{3:3}:
       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:381 [inline]
       blkdev_common_ioctl+0x881/0x2460 block/ioctl.c:511
       blkdev_ioctl+0x4eb/0x6f0 block/ioctl.c:633
       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

-> #1 (&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:585
       blkdev_get_by_dev+0x45c/0x600 block/bdev.c:818
       bdev_open_by_dev+0x77/0x100 block/bdev.c:859
       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:3386
       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:1578
       kernel_init+0x1d/0x1c0 init/main.c:1455
       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 (bdev_lock){+.+.}-{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
       __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:527
       truncate_bdev_range+0x4e/0x260 block/bdev.c:105
       blkdev_fallocate+0x50d/0x6a0 block/fops.c:798
       vfs_fallocate+0x58e/0x700 fs/open.c:324
       ksys_fallocate fs/open.c:347 [inline]
       __do_sys_fallocate fs/open.c:355 [inline]
       __se_sys_fallocate fs/open.c:353 [inline]
       __x64_sys_fallocate+0xc1/0x110 fs/open.c:353
       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:
  bdev_lock --> &sb->s_type->i_mutex_key#8 --> mapping.invalidate_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(mapping.invalidate_lock);
                               lock(&sb->s_type->i_mutex_key#8);
                               lock(mapping.invalidate_lock);
  lock(bdev_lock);

 *** DEADLOCK ***

2 locks held by syz.0.17/5920:
 #0: ffff888148c89eb0 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #0: ffff888148c89eb0 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: blkdev_fallocate+0x205/0x6a0 block/fops.c:788
 #1: ffff888148c8a040 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:849 [inline]
 #1: ffff888148c8a040 (mapping.invalidate_lock){++++}-{3:3}, at: blkdev_fallocate+0x22b/0x6a0 block/fops.c:789

stack backtrace:
CPU: 0 PID: 5920 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 __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:527
 truncate_bdev_range+0x4e/0x260 block/bdev.c:105
 blkdev_fallocate+0x50d/0x6a0 block/fops.c:798
 vfs_fallocate+0x58e/0x700 fs/open.c:324
 ksys_fallocate fs/open.c:347 [inline]
 __do_sys_fallocate fs/open.c:355 [inline]
 __se_sys_fallocate fs/open.c:353 [inline]
 __x64_sys_fallocate+0xc1/0x110 fs/open.c:353
 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: 0033:0x7f4f3af8f749
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:00007ffffdad1288 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f4f3b1e5fa0 RCX: 00007f4f3af8f749
RDX: 0000000000004000 RSI: 0000000000000010 RDI: 0000000000000004
RBP: 00007f4f3b013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4f3b1e5fa0 R14: 00007f4f3b1e5fa0 R15: 0000000000000004
 </TASK>