From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f79.google.com (mail-ot1-f79.google.com [209.85.210.79]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2055D4071CA for ; Mon, 8 Jun 2026 23:15:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780960534; cv=none; b=bA1G/gjZAEgWez579NMW3ZtbvcioO5uiP0MWbr53v+rD+1fizGDWJ3gyFpivrOI7blTo5QvqHUvnvu2kwTMGBvoMwO+GffKIVaw6c4UDZvXikawRFrHSkRRlQcjAgHJM1wu3dqF7NxUyOu+sOtbrYt2/kbCaqP11OYRl1dEkBfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780960534; c=relaxed/simple; bh=u/c2UJgHba4bu+luPnrKhYslUgNgA/CgLZn1nBCNkU4=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=DBB0fco36q0Pm4dpyzJC62mOkIJ2K9TFpQYtzl4ZPPkZQ/mMAYJ+m12J1Kj+yVMTO3tog+ZguXM3lhEEIiqKRNUlWz92S7s4QG7Sx3EhSzFNUylJC/hKwbh7AnQNxq/3KdfQQALPMsdneUgJF9eGwGcrhc1qsn5WRZ+gWBOEyoY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.210.79 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-ot1-f79.google.com with SMTP id 46e09a7af769-7e6d9be94a2so3842578a34.1 for ; Mon, 08 Jun 2026 16:15:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780960532; x=1781565332; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=L5S5wmIGUcqFIkrVsA5/P1zutrYnuAieN/KICqmjtD4=; b=M3lcbcpnoITOoQkz3DHc4cPYPw6Y33p+H+rVf414QQkXVhwKH55dD8IXMymzR8p2au 1tqHH+6nN4dlCejlVGyd1hSPUZvZVQH4EyJmy2N7HqTXIjJKSVrDNAaEEiNfHO4dpGPM K5N5JMMvRheGv01JLCbrkYedDiHv24N+2Zjyz8HK53UyQCAaiLljCZXSUKSsjUdwVhm1 IYC8JRKSZ/zT4AczYQsaVZf7336Nx2XIjpCBQ6LLplJa4kmqRD4mwGc7ysUIv3GnxgxY 2S08U5J+wrN+9CuQrxuDkeqlulJ4apjuO+yEZD9lo7VcH0xKMf5kEknZ4IBcArRrJxmr x7SQ== X-Forwarded-Encrypted: i=1; AFNElJ+go/2d7x1XJoqLquDJ3f4oEnZUBDWXwCe/D7jDbjXiJ4yds3CRc9Piu8Yipc3LQHtIagb1McmCzdOOeiyh@vger.kernel.org X-Gm-Message-State: AOJu0YxBm5gziqFguy8GKe0na1eKv02QSPcr2FAsOV0nUuygpMHPZmn2 OOV4a0dMn21EGfDhcA3v+r7BKNRZC0Xz/bO0dP+HWlA/52EPWaH1x1m1emAeVSliIkfLRRAQCTI TIatXIwFzPJq9tCbR6CySrU55qrOFcF3wOoZ1tU2gDxo+3ARxqDdguiGIOsM= Precedence: bulk X-Mailing-List: linux-unionfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1514:b0:69d:9288:66bc with SMTP id 006d021491bc7-69e68b09a6fmr8367147eaf.5.1780960532137; Mon, 08 Jun 2026 16:15:32 -0700 (PDT) Date: Mon, 08 Jun 2026 16:15:32 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a274d14.c25708ab.1b19ef.0016.GAE@google.com> Subject: [syzbot] [overlayfs?] possible deadlock in mnt_want_write (8) From: syzbot To: amir73il@gmail.com, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: ec7ef10b77a6 Merge branch 'for-next/core' into for-kernelci 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=17a17dd2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=522222e78af9b9d2 dashboard link: https://syzkaller.appspot.com/bug?extid=1e5626d6fd59853cbfaa compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 userspace arch: arm64 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/22c81873d970/disk-ec7ef10b.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/ba2c817c4ea9/vmlinux-ec7ef10b.xz kernel image: https://storage.googleapis.com/syzbot-assets/04c4e1c1bb56/Image-ec7ef10b.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+1e5626d6fd59853cbfaa@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.5.673/7842 is trying to acquire lock: ffff0000d814a410 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:493 but task is already holding lock: ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline] ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_nlink_start+0xc8/0x350 fs/overlayfs/util.c:1173 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&ovl_i_lock_key[depth]){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x160/0xef8 kernel/locking/mutex.c:820 mutex_lock_interruptible_nested+0x24/0x30 kernel/locking/mutex.c:898 ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline] ovl_copy_up_start+0x58/0x264 fs/overlayfs/util.c:735 ovl_copy_up_one fs/overlayfs/copy_up.c:1182 [inline] ovl_copy_up_flags+0x768/0x28a4 fs/overlayfs/copy_up.c:1243 ovl_copy_up+0x24/0x34 fs/overlayfs/copy_up.c:1282 ovl_link+0x8c/0x26c fs/overlayfs/dir.c:774 vfs_link+0x40c/0x580 fs/namei.c:5774 filename_linkat+0x224/0x478 fs/namei.c:5842 __do_sys_linkat fs/namei.c:5868 [inline] __se_sys_linkat fs/namei.c:5863 [inline] __arm64_sys_linkat+0xe8/0x118 fs/namei.c:5863 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #1 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1625 inode_lock include/linux/fs.h:1029 [inline] lock_two_nondirectories+0xc4/0x148 fs/inode.c:1254 ext4_move_extents+0x194/0x3580 fs/ext4/move_extent.c:589 __ext4_ioctl fs/ext4/ioctl.c:1657 [inline] ext4_ioctl+0x2a14/0x4234 fs/ext4/ioctl.c:1922 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #0 (sb_writers#3){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1780/0x2f44 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x368 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write+0x5c/0x294 include/linux/fs/super.h:125 mnt_want_write+0x44/0x9c fs/namespace.c:493 ovl_want_write fs/overlayfs/util.c:38 [inline] ovl_nlink_start+0x154/0x350 fs/overlayfs/util.c:1177 ovl_do_remove+0x1c0/0xa04 fs/overlayfs/dir.c:954 ovl_rmdir+0x24/0x34 fs/overlayfs/dir.c:993 vfs_rmdir+0x34c/0x5a0 fs/namei.c:5366 filename_rmdir+0x208/0x3dc fs/namei.c:5421 __do_sys_unlinkat fs/namei.c:5596 [inline] __se_sys_unlinkat fs/namei.c:5589 [inline] __arm64_sys_unlinkat+0xc8/0x104 fs/namei.c:5589 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 other info that might help us debug this: Chain exists of: sb_writers#3 --> &ovl_i_mutex_key[depth] --> &ovl_i_lock_key[depth] Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ovl_i_lock_key[depth]); lock(&ovl_i_mutex_key[depth]); lock(&ovl_i_lock_key[depth]); rlock(sb_writers#3); *** DEADLOCK *** 4 locks held by syz.5.673/7842: #0: ffff0000d924c410 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:493 #1: ffff0000dc944300 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1074 [inline] #1: ffff0000dc944300 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: __start_dirop+0xa0/0xf4 fs/namei.c:2914 #2: ffff0000dc946ec0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline] #2: ffff0000dc946ec0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: vfs_rmdir+0x110/0x5a0 fs/namei.c:5351 #3: ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline] #3: ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_nlink_start+0xc8/0x350 fs/overlayfs/util.c:1173 stack backtrace: CPU: 1 UID: 0 PID: 7842 Comm: syz.5.673 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 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_circular_bug+0x328/0x330 kernel/locking/lockdep.c:2043 check_noncircular+0x158/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1780/0x2f44 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x368 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write+0x5c/0x294 include/linux/fs/super.h:125 mnt_want_write+0x44/0x9c fs/namespace.c:493 ovl_want_write fs/overlayfs/util.c:38 [inline] ovl_nlink_start+0x154/0x350 fs/overlayfs/util.c:1177 ovl_do_remove+0x1c0/0xa04 fs/overlayfs/dir.c:954 ovl_rmdir+0x24/0x34 fs/overlayfs/dir.c:993 vfs_rmdir+0x34c/0x5a0 fs/namei.c:5366 filename_rmdir+0x208/0x3dc fs/namei.c:5421 __do_sys_unlinkat fs/namei.c:5596 [inline] __se_sys_unlinkat fs/namei.c:5589 [inline] __arm64_sys_unlinkat+0xc8/0x104 fs/namei.c:5589 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 --- 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@googlegroups.com. 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 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 If you want to undo deduplication, reply with: #syz undup