From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f197.google.com (mail-oi1-f197.google.com [209.85.167.197]) (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 F363D514752 for ; Fri, 2 Oct 2026 20:11:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790971893; cv=none; b=P+uDMKOQFXDzrok51XiCN8dzHJGQaBt2RatknEOyLzXBe9YahpipOUk0nugVFd4blUMBexLVZQKOhUIqwSPuvznoHu0RsM04s8GF+XNikpxcnWeVKiiaaLDXEkCH2y8pSsJGKTaoO2cP0gyVd41WT+GQI5nM7bm6oMTaTiOnzLk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790971893; c=relaxed/simple; bh=khPh14Pceb2xrIP/Q35E8Ty/zjps/OZrik46SvHKJwU=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=aFU/1P1KRW1Nd2mfVQvIi+Zt2jIEFOv7LxVv1Qo5ktx6tAUy0K92P4Uc/HcNfPGd94JRWub+xSFtsp15kDINLDGZOrCCkQ4qHyzOnVuBC7ExrdcHMSDBRi89BtOEmxfty8QsTbwg9VyiDchRpVteOGVLn97wf9537QQaE8FHrlA= 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=209.85.167.197 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-oi1-f197.google.com with SMTP id 5614622812f47-4ea2c058e67so8264963b6e.1 for ; Fri, 02 Oct 2026 13:11:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790971891; x=1791576691; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=sMGooLKsXYFPTfvyOy4AlOUY1TGy9Q+HaH3JlZUNrJo=; b=f4ESQqTb/NlEuo4nIBuNH/1QRMegv4oWRdJwUr/VfNApPDH5htkPvI7C12r5sKsXIc JbGJd1Q4+71jGx3B6vBS6KrTHAFviJ1nck9RyJzOpBKznLuAP0GuSfD2ABJLiyZYAaf1 xkW1F13pPaYbt2A+tW2e1NuWHuegYVFv4RmvItBZRpTl7+Guzc2m2rgHKC5UOxUqTYwS /B2uJ8pktAGo/CXc40GzGF2XDhFaEFZVJVVhI2yz8e25Vh7CT5ww1SYefTkCZsUhYzyf zx8eoAgW8IWIUDCrrIp2Wy1+Kfy06MHdeoCMB5DuVgZpRTEIIz1qwk2gANyDL/i7MTxZ szrg== X-Forwarded-Encrypted: i=1; AKwUvBy6Og2ebUejAQMkQ+4r4v2ohU0P8PQpGIFxEBH3o/el4t/UUJAQEqQfVUnE88pQPpDBC0Qyv4s38BbkEck=@vger.kernel.org X-Gm-Message-State: AFuF++ljPvU5MtjnCOZgx84zDnT1WU2VMP9VkJVxwGSre6+XFBod00ne OK5CtxtaerSw33XJNY0VSM1DULt93XNGkxyAH8PpwHjdKMXrAw0Fr1SOUlsGCL9VHeRUapxqSYC /gQj3X2JRGK85UFeooI+0H0eYtsxi6Ydxhcijq7h6lkHHlaSZSelBVw9WiR8= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:4f14:b0:4c4:d8a0:2773 with SMTP id 5614622812f47-4f67a0f6c02mr483176b6e.32.1790971890910; Fri, 02 Oct 2026 13:11:30 -0700 (PDT) Date: Fri, 02 Oct 2026 13:11:30 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ac00ff2.9ad129c8.3858c0.0004.GAE@google.com> Subject: [syzbot] [overlayfs?] possible deadlock in iterate_dir (4) 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: 6474fa070f2b Add linux-next specific files for 20260929 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=11744725580000 kernel config: https://syzkaller.appspot.com/x/.config?x=3477d5a04d788556 dashboard link: https://syzkaller.appspot.com/bug?extid=7c4b3d05083880a09cdd compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/0b184b600605/disk-6474fa07.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/71aa06781faf/vmlinux-6474fa07.xz kernel image: https://storage.googleapis.com/syzbot-assets/250dcdc25f2b/bzImage-6474fa07.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7c4b3d05083880a09cdd@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.241/6613 is trying to acquire lock: ffff888079d74140 (&type->i_mutex_dir_key#4){++++}-{4:4}, at: iterate_dir+0x209/0x4d0 fs/readdir.c:103 but task is already holding lock: ffff888059293d88 (&ovl_i_mutex_dir_key[depth]#2){++++}-{4:4}, at: wrap_directory_iterator+0x5a/0xe0 fs/readdir.c:56 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&ovl_i_mutex_dir_key[depth]#2){++++}-{4:4}: down_read+0x45/0x320 kernel/locking/rwsem.c:1574 inode_lock_shared include/linux/fs.h:1039 [inline] lookup_slow+0x46/0x80 fs/namei.c:1935 ovl_lookup_positive_unlocked fs/overlayfs/namei.c:216 [inline] ovl_lookup_single+0x323/0xe90 fs/overlayfs/namei.c:260 ovl_lookup_layer+0x377/0x440 fs/overlayfs/namei.c:365 ovl_lookup_layers fs/overlayfs/namei.c:1168 [inline] ovl_lookup+0x9ae/0x1c80 fs/overlayfs/namei.c:1403 lookup_open+0x94b/0x1970 fs/namei.c:4530 open_last_lookups fs/namei.c:4769 [inline] path_openat+0x673/0x1da0 fs/namei.c:5008 do_file_open+0x23e/0x4a0 fs/namei.c:5040 do_sys_openat2+0x115/0x200 fs/open.c:1442 do_sys_open fs/open.c:1448 [inline] __do_sys_openat fs/open.c:1464 [inline] __se_sys_openat fs/open.c:1459 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1459 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (DCACHE_PAR_LOOKUP){+.+.}-{0:0}: d_wait_lookup fs/dcache.c:2838 [inline] __d_alloc_parallel+0xc32/0x1700 fs/dcache.c:2942 __lookup_slow+0x82/0x2f0 fs/namei.c:1904 lookup_slow+0x59/0x80 fs/namei.c:1936 walk_component fs/namei.c:2282 [inline] lookup_last fs/namei.c:2789 [inline] path_lookupat+0x3f5/0x8c0 fs/namei.c:2813 filename_lookup+0x265/0x5d0 fs/namei.c:2842 do_readlinkat+0xe3/0x510 fs/stat.c:571 __do_sys_readlink fs/stat.c:605 [inline] __se_sys_readlink fs/stat.c:602 [inline] __x64_sys_readlink+0x7f/0x90 fs/stat.c:602 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&type->i_mutex_dir_key#4){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 down_read_killable+0x4b/0x3b0 kernel/locking/rwsem.c:1599 iterate_dir+0x209/0x4d0 fs/readdir.c:103 ovl_dir_read+0x141/0x4a0 fs/overlayfs/readdir.c:388 ovl_dir_read_merged+0x2fb/0x520 fs/overlayfs/readdir.c:451 ovl_cache_get fs/overlayfs/readdir.c:504 [inline] ovl_iterate_merged fs/overlayfs/readdir.c:846 [inline] ovl_iterate+0xd5a/0x2160 fs/overlayfs/readdir.c:906 wrap_directory_iterator+0x96/0xe0 fs/readdir.c:67 iterate_dir+0x2e2/0x4d0 fs/readdir.c:110 __do_sys_getdents64 fs/readdir.c:399 [inline] __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#4 --> DCACHE_PAR_LOOKUP --> &ovl_i_mutex_dir_key[depth]#2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ovl_i_mutex_dir_key[depth]#2); lock(DCACHE_PAR_LOOKUP); lock(&ovl_i_mutex_dir_key[depth]#2); rlock(&type->i_mutex_dir_key#4); *** DEADLOCK *** locks held by syz.1.241/6613: 2, last CPU#1: #0: ffff88807eb65cf0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408 #1: ffff888059293d88 (&ovl_i_mutex_dir_key[depth]#2){++++}-{4:4}, at: wrap_directory_iterator+0x5a/0xe0 fs/readdir.c:56 stack backtrace: CPU: 1 UID: 0 PID: 6613 Comm: syz.1.241 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219 check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 down_read_killable+0x4b/0x3b0 kernel/locking/rwsem.c:1599 iterate_dir+0x209/0x4d0 fs/readdir.c:103 ovl_dir_read+0x141/0x4a0 fs/overlayfs/readdir.c:388 ovl_dir_read_merged+0x2fb/0x520 fs/overlayfs/readdir.c:451 ovl_cache_get fs/overlayfs/readdir.c:504 [inline] ovl_iterate_merged fs/overlayfs/readdir.c:846 [inline] ovl_iterate+0xd5a/0x2160 fs/overlayfs/readdir.c:906 wrap_directory_iterator+0x96/0xe0 fs/readdir.c:67 iterate_dir+0x2e2/0x4d0 fs/readdir.c:110 __do_sys_getdents64 fs/readdir.c:399 [inline] __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5cfbb9e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5cfc9c0028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f5cfbe25fa0 RCX: 00007f5cfbb9e159 RDX: 0000000000001000 RSI: 0000200000001dc0 RDI: 0000000000000009 RBP: 00007f5cfbc3506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5cfbe26038 R14: 00007f5cfbe25fa0 R15: 00007ffe433bef38 --- 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