On Thu, Sep 4, 2025 at 7:37 PM syzbot <syzbot+1090a418b58c19e9a57b@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 8f5ae30d69d7 Linux 6.17-rc1 > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > console output: https://syzkaller.appspot.com/x/log.txt?x=15322e62580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=8c5ac3d8b8abfcb > dashboard link: https://syzkaller.appspot.com/bug?extid=1090a418b58c19e9a57b > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 > userspace arch: arm64 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=121cea42580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15589e62580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/18a2e4bd0c4a/disk-8f5ae30d.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/3b5395881b25/vmlinux-8f5ae30d.xz > kernel image: https://storage.googleapis.com/syzbot-assets/e875f4e3b7ff/Image-8f5ae30d.gz.xz > mounted in repro: https://storage.googleapis.com/syzbot-assets/cf46540aa8ee/mount_0.gz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+1090a418b58c19e9a57b@xxxxxxxxxxxxxxxxxxxxxxxxx > > bcachefs (loop0): resume_logged_ops... done > bcachefs (loop0): delete_dead_inodes... done > bcachefs (loop0): done starting filesystem > ============================================ > WARNING: possible recursive locking detected > 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 Not tainted > -------------------------------------------- > syz.0.19/6755 is trying to acquire lock: > ffff0000ec7c5c68 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline] > ffff0000ec7c5c68 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: vfs_link+0x2f0/0x590 fs/namei.c:4845 > > but task is already holding lock: > ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline] > ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: ovl_create_temp fs/overlayfs/dir.c:228 [inline] > ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: ovl_create_over_whiteout fs/overlayfs/dir.c:473 [inline] > ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: ovl_create_or_link+0x608/0x11b8 fs/overlayfs/dir.c:629 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&sb->s_type->i_mutex_key#21); > lock(&sb->s_type->i_mutex_key#21); > > *** DEADLOCK *** > > May be due to missing lock nesting notation > > 6 locks held by syz.0.19/6755: > #0: ffff0000dcc7e428 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:557 > #1: ffff0000ec7b1e50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:914 [inline] > #1: ffff0000ec7b1e50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: filename_create+0x1ac/0x32c fs/namei.c:4139 > #2: ffff0000ec7b2418 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline] > #2: ffff0000ec7b2418 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: vfs_link+0x2f0/0x590 fs/namei.c:4845 > #3: ffff0000ec7b27d0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:672 [inline] > #3: ffff0000ec7b27d0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_nlink_start+0x2fc/0x6e0 fs/overlayfs/util.c:1176 > #4: ffff0000d2034428 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:557 > #5: ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline] > #5: ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: ovl_create_temp fs/overlayfs/dir.c:228 [inline] > #5: ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: ovl_create_over_whiteout fs/overlayfs/dir.c:473 [inline] > #5: ffff0000ec7c54d0 (&sb->s_type->i_mutex_key#21){++++}-{4:4}, at: ovl_create_or_link+0x608/0x11b8 fs/overlayfs/dir.c:629 > > stack backtrace: > CPU: 0 UID: 0 PID: 6755 Comm: syz.0.19 Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 > Call trace: > show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) > __dump_stack+0x30/0x40 lib/dump_stack.c:94 > dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 > dump_stack+0x1c/0x28 lib/dump_stack.c:129 > print_deadlock_bug+0x2e8/0x2f0 kernel/locking/lockdep.c:3041 > check_deadlock kernel/locking/lockdep.c:3093 [inline] > validate_chain kernel/locking/lockdep.c:3895 [inline] > __lock_acquire+0x2940/0x30a4 kernel/locking/lockdep.c:5237 > lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 > down_write+0x50/0xc0 kernel/locking/rwsem.c:1590 > inode_lock include/linux/fs.h:869 [inline] > vfs_link+0x2f0/0x590 fs/namei.c:4845 > ovl_do_link fs/overlayfs/overlayfs.h:227 [inline] > ovl_create_real+0x11c/0x3fc fs/overlayfs/dir.c:179 > ovl_create_temp fs/overlayfs/dir.c:229 [inline] > ovl_create_over_whiteout fs/overlayfs/dir.c:473 [inline] > ovl_create_or_link+0x62c/0x11b8 fs/overlayfs/dir.c:629 > ovl_link+0x1d8/0x258 fs/overlayfs/dir.c:746 > vfs_link+0x3e0/0x590 fs/namei.c:4854 > do_linkat+0x224/0x48c fs/namei.c:4924 > __do_sys_linkat fs/namei.c:4952 [inline] > __se_sys_linkat fs/namei.c:4949 [inline] > __arm64_sys_linkat+0xdc/0xf8 fs/namei.c:4949 > __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] > invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 > el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 > do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 > el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 > el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing. > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report #syz dup: WARNING in shmem_unlink Thanks, Amir.
