From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f77.google.com (mail-oo1-f77.google.com [209.85.161.77]) (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 D07C116DEB1 for ; Mon, 8 Dec 2025 00:54:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.77 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765155265; cv=none; b=NQWpGlpCuTCYJSdflF25S1XE26MFU7k8xcez2INMpjcU1bNmD6axnFg/4bi5jxcGZxXfa7ZrpPKsewPJqNLOKhELaZmLpBb0TZq++dWz9sxZTJjUbgVqc+9D74XUSJ2YDt8qFLJN/1p686v0ohea5Ag7NgXMBBsfCN/PxYtx//s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765155265; c=relaxed/simple; bh=/o41xEs0sEdxf2fQ6yykbW83mjM6XxTKr3E8aCQ3LMw=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=BO25eqFe2J+lvPYvZmL57RmWeLmsJntOU3FJ34fNyuhKijcqsk886cSuebHGYRnMIcnzkIJODnr9htQTNXOR+/gF1vLPk2i020q6Tzk//nKwcm/lWwQBS4H/874hsOuGJn47lu3gQb5J1/8ZGc83hT3B5gJpoRaWWzc8aOxFcRc= 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=209.85.161.77 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-oo1-f77.google.com with SMTP id 006d021491bc7-656b3efc41aso4731888eaf.3 for ; Sun, 07 Dec 2025 16:54:23 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765155263; x=1765760063; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=1EdWlikPG84Jcbzgl/AUO8KwIo1Jk1ztUHjenfDFld4=; b=iLTRHT7achb/I3z94anNvFGzn84XHrs1hkDJ3r13SISgXASzbJ/gdBbeW2a4yFFCUe vLGsfbMa8/OZxSj/mxXiGmUGAqokliHlWZfI8anmvm5UaSIaeFvl2LwQ+yTf+mQD8PzB Z9qrM0BFLfdm3CFkZg8FKVbl2GE531mv2XwSPF0BCFtuA/IIrh3s+TI4W5cU6iz4Aa6g m99j44ZdylHAdDPCdEwOLCpAQq6WOAU0FqdoEr1ErFzz4A5ZYWe7k0SdEn2Cbcq0+c8S lHQH8G/nrKatkeEFJe6bVOdbVWT9JUf/bDECj7MLYQz7rL9H8dJo6ed7szX/xWZEtdbs wAMw== X-Forwarded-Encrypted: i=1; AJvYcCVFANY2le1CTqTfWgCbjzB2Qo27jCqj4Me1TxkgHhzA1jT51rlOT1U5W+n/+0uMKH6WQGByAz4j8mj6jG0=@vger.kernel.org X-Gm-Message-State: AOJu0Yw+V0IfP45v+NePndcvuJffdb9otcraLaXTCFo/AR6o+ZdKoDoq lwJ1974rn5LqxxAjuWgK+kj9H39zTGcHPgYj8UNhPsxOfYeMzK6nltaFQTwYaM+S3jXKfzykgX+ 4RaLe3nmNpbXQlZufky+Hsd55RNSxEn5D0zaK/D1HzuqKQrUORidA2YKJ+uQ= X-Google-Smtp-Source: AGHT+IEYdEwIJuXlRXS7qyX+o5mdGOBIL0cNiGkxDkA2F6SAk2CrsGraGJFTY+VrjNJgFcb/4rk8yNRWQDGCGOmehhUAoGQkW1PG Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1993:b0:659:9a49:8f4e with SMTP id 006d021491bc7-6599a8e16c5mr2496943eaf.19.1765155263011; Sun, 07 Dec 2025 16:54:23 -0800 (PST) Date: Sun, 07 Dec 2025 16:54:22 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <693621be.a70a0220.38f243.0072.GAE@google.com> Subject: [syzbot] [btrfs?] possible deadlock in join_transaction (3) From: syzbot To: clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 05c93f3395ed 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=14386ab4580000 kernel config: https://syzkaller.appspot.com/x/.config?x=3b5338ad1e59a06c dashboard link: https://syzkaller.appspot.com/bug?extid=c597e3e4382fe9c65845 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 userspace arch: arm64 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/6b5c913e373c/disk-05c93f33.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/15e75f1266ef/vmlinux-05c93f33.xz kernel image: https://storage.googleapis.com/syzbot-assets/dd930129c578/Image-05c93f33.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c597e3e4382fe9c65845@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u8:9/7952 is trying to acquire lock: ffff0000f7ac2538 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x134/0xb5c fs/btrfs/transaction.c:317 but task is already holding lock: ffff0000d5af8610 (sb_internal#4){.+.+}-{0:0}, at: btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (sb_internal#4){.+.+}-{0:0}: 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.h:1916 [inline] sb_start_intwrite include/linux/fs.h:2099 [inline] start_transaction+0x5bc/0x155c fs/btrfs/transaction.c:699 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:830 btrfs_dirty_inode+0x90/0x190 fs/btrfs/inode.c:6272 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6306 inode_update_time fs/inode.c:2129 [inline] touch_atime+0x2e4/0x818 fs/inode.c:2202 file_accessed include/linux/fs.h:2673 [inline] btrfs_file_mmap_prepare+0xc4/0x130 fs/btrfs/file.c:2049 vfs_mmap_prepare include/linux/fs.h:2410 [inline] call_mmap_prepare mm/vma.c:2586 [inline] __mmap_region mm/vma.c:2654 [inline] mmap_region+0x940/0x1d28 mm/vma.c:2740 do_mmap+0x968/0xfac mm/mmap.c:558 vm_mmap_pgoff+0x2d8/0x45c mm/util.c:581 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:604 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #4 (&mm->mmap_lock){++++}-{4:4}: down_read_killable+0x60/0x32c kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x28/0x8c include/linux/mmap_lock.h:377 get_mmap_lock_carefully mm/mmap_lock.c:377 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/mmap_lock.c:428 do_page_fault+0x50c/0x13cc arch/arm64/mm/fault.c:678 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:793 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:933 el1_abort+0x40/0x64 arch/arm64/kernel/entry-common.c:303 el1h_64_sync_handler+0x50/0xfc arch/arm64/kernel/entry-common.c:437 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:591 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] filldir64+0x2ec/0x6bc fs/readdir.c:379 dir_emit include/linux/fs.h:3988 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1910 iterate_dir+0x2dc/0x478 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64 fs/readdir.c:396 [inline] __arm64_sys_getdents64+0x110/0x2fc fs/readdir.c:396 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #3 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x48/0x60c fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xd4/0x12c fs/kernfs/dir.c:1093 sysfs_create_dir_ns+0x114/0x24c fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a8/0xb20 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x118/0x17c lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x110/0x268 fs/btrfs/sysfs.c:2645 btrfs_quota_enable+0x210/0x2438 fs/btrfs/qgroup.c:1022 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3667 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5333 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+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #2 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598 __mutex_lock kernel/locking/mutex.c:760 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812 btrfs_quota_enable+0x24c/0x2438 fs/btrfs/qgroup.c:1051 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3667 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5333 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+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #1 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x190/0xb5c fs/btrfs/transaction.c:321 start_transaction+0x778/0x155c fs/btrfs/transaction.c:705 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 btrfs_rebuild_free_space_tree+0xac/0x6c0 fs/btrfs/free-space-tree.c:1340 btrfs_start_pre_rw_mount+0xed8/0x1728 fs/btrfs/disk-io.c:3062 open_ctree+0x24cc/0x358c fs/btrfs/disk-io.c:3619 btrfs_fill_super fs/btrfs/super.c:987 [inline] btrfs_get_tree_super fs/btrfs/super.c:1951 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2094 [inline] btrfs_get_tree+0xd94/0x15dc fs/btrfs/super.c:2128 vfs_get_tree+0x90/0x28c fs/super.c:1758 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3642 [inline] do_new_mount+0x284/0x944 fs/namespace.c:3718 path_mount+0x5b4/0xdfc fs/namespace.c:4028 do_mount fs/namespace.c:4041 [inline] __do_sys_mount fs/namespace.c:4229 [inline] __se_sys_mount fs/namespace.c:4206 [inline] __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4206 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #0 (btrfs_trans_num_writers){++++}-{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+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 join_transaction+0x164/0xb5c fs/btrfs/transaction.c:320 start_transaction+0x778/0x155c fs/btrfs/transaction.c:705 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 btrfs_qgroup_rescan_worker+0x280/0x19f8 fs/btrfs/qgroup.c:3824 btrfs_work_helper+0x380/0xca8 fs/btrfs/async-thread.c:312 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 other info that might help us debug this: Chain exists of: btrfs_trans_num_writers --> &mm->mmap_lock --> sb_internal#4 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(sb_internal#4); lock(&mm->mmap_lock); lock(sb_internal#4); rlock(btrfs_trans_num_writers); *** DEADLOCK *** 3 locks held by kworker/u8:9/7952: #0: ffff0000f51cb148 ((wq_completion)btrfs-qgroup-rescan){+.+.}-{0:0}, at: process_one_work+0x63c/0x155c kernel/workqueue.c:3237 #1: ffff8000a43c7be0 ((work_completion)(&work->normal_work)){+.+.}-{0:0}, at: process_one_work+0x6d4/0x155c kernel/workqueue.c:3237 #2: ffff0000d5af8610 (sb_internal#4){.+.+}-{0:0}, at: btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 stack backtrace: CPU: 0 UID: 0 PID: 7952 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Workqueue: btrfs-qgroup-rescan btrfs_work_helper 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+0x324/0x32c kernel/locking/lockdep.c:2043 check_noncircular+0x154/0x174 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+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 join_transaction+0x164/0xb5c fs/btrfs/transaction.c:320 start_transaction+0x778/0x155c fs/btrfs/transaction.c:705 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 btrfs_qgroup_rescan_worker+0x280/0x19f8 fs/btrfs/qgroup.c:3824 btrfs_work_helper+0x380/0xca8 fs/btrfs/async-thread.c:312 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 BTRFS info (device loop7): qgroup scan completed (inconsistency flag cleared) --- 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