From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f70.google.com (mail-oo1-f70.google.com [209.85.161.70]) (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 0355A1A9F94 for ; Sun, 22 Feb 2026 20:59:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.70 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771793976; cv=none; b=BnwkWrUyI9zEuhj9qFzB6zCftfzZ3SMaW8mss0BBPaRdKtf+nFX3d7sSxQHWMDvBd+M1u2GG1npeC8HNL+/7OL8ei5iKOOm2I6BGpGRFpUiwL+qfrl7a90R9CyQIEVseE3Woc9Flf8JhlWlhn5z6v+m+SGAFjc++k5PI0PrSk8w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771793976; c=relaxed/simple; bh=gHbqcyWrnknI5+8IkEGauVFljz8Po3Uefy8XWruAvus=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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006d021491bc7-679c4278245mr3416090eaf.18.1771793973977; Sun, 22 Feb 2026 12:59:33 -0800 (PST) Date: Sun, 22 Feb 2026 12:59:33 -0800 In-Reply-To: <6953bc09.050a0220.329c0f.0592.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <699b6e35.a70a0220.2c38d7.0182.GAE@google.com> Subject: Re: [syzbot] [ext4?] possible deadlock in wait_transaction_locked (3) From: syzbot To: jack@suse.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tytso@mit.edu Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 32a92f8c8932 Convert more 'alloc_obj' cases to default GFP.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16a7d95a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=35a2f9886a9bccfa dashboard link: https://syzkaller.appspot.com/bug?extid=5d19358d7eb30ffb0cc5 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1543055a580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104f8006580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/1c446301a138/disk-32a92f8c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/245be1b900af/vmlinux-32a92f8c.xz kernel image: https://storage.googleapis.com/syzbot-assets/16e0d6bc53db/bzImage-32a92f8c.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/1c55fb38005a/mount_0.gz fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=14a3a55a580000) IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+5d19358d7eb30ffb0cc5@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u8:11/1186 is trying to acquire lock: ffff888036d5ebb0 (jbd2_handle){++++}-{0:0}, at: wait_transaction_locked+0x1a9/0x280 fs/jbd2/transaction.c:151 but task is already holding lock: ffff888036d52c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: percpu_down_read include/linux/percpu-rwsem.h:77 [inline] ffff888036d52c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1813 [inline] ffff888036d52c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x205/0x3b0 fs/ext4/inode.c:3018 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sbi->s_writepages_rwsem){++++}-{0:0}: percpu_down_read_internal+0x48/0x1d0 include/linux/percpu-rwsem.h:53 percpu_down_read include/linux/percpu-rwsem.h:77 [inline] ext4_writepages_down_read fs/ext4/ext4.h:1813 [inline] ext4_writepages+0x205/0x3b0 fs/ext4/inode.c:3018 do_writepages+0x32e/0x550 mm/page-writeback.c:2554 __writeback_single_inode+0x133/0x11a0 fs/fs-writeback.c:1749 writeback_single_inode+0x488/0xd60 fs/fs-writeback.c:1868 write_inode_now+0x1c2/0x290 fs/fs-writeback.c:2953 iput_final fs/inode.c:1956 [inline] iput+0x8c1/0xe80 fs/inode.c:2015 ext4_xattr_block_set+0x1fd4/0x2ad0 fs/ext4/xattr.c:2204 ext4_xattr_move_to_block fs/ext4/xattr.c:2669 [inline] ext4_xattr_make_inode_space fs/ext4/xattr.c:2744 [inline] ext4_expand_extra_isize_ea+0x12cf/0x1ea0 fs/ext4/xattr.c:2832 __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6297 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6340 [inline] __ext4_mark_inode_dirty+0x45c/0x730 fs/ext4/inode.c:6418 ext4_evict_inode+0x7a1/0xeb0 fs/ext4/inode.c:255 evict+0x61e/0xb10 fs/inode.c:846 ext4_orphan_cleanup+0xc38/0x1470 fs/ext4/orphan.c:472 __ext4_fill_super fs/ext4/super.c:5668 [inline] ext4_fill_super+0x5a0b/0x6320 fs/ext4/super.c:5791 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3760 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3836 do_mount fs/namespace.c:4159 [inline] __do_sys_mount fs/namespace.c:4348 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4325 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&ei->xattr_sem){++++}-{4:4}: down_write+0x3a/0x50 kernel/locking/rwsem.c:1590 ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline] ext4_xattr_set_handle+0x19c/0x14c0 fs/ext4/xattr.c:2372 ext4_initxattrs+0x9f/0x110 fs/ext4/xattr_security.c:44 security_inode_init_security+0x296/0x3d0 security/security.c:1344 __ext4_new_inode+0x332f/0x3d20 fs/ext4/ialloc.c:1324 ext4_create+0x233/0x470 fs/ext4/namei.c:2820 lookup_open fs/namei.c:4483 [inline] open_last_lookups fs/namei.c:4583 [inline] path_openat+0x13b4/0x38a0 fs/namei.c:4827 do_file_open+0x23e/0x4a0 fs/namei.c:4859 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (jbd2_handle){++++}-{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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 wait_transaction_locked+0x1c2/0x280 fs/jbd2/transaction.c:151 add_transaction_credits fs/jbd2/transaction.c:222 [inline] start_this_handle+0x7dc/0x2290 fs/jbd2/transaction.c:403 jbd2__journal_start+0x2c0/0x5b0 fs/jbd2/transaction.c:501 __ext4_journal_start_sb+0x203/0x620 fs/ext4/ext4_jbd2.c:114 __ext4_journal_start fs/ext4/ext4_jbd2.h:242 [inline] ext4_do_writepages+0xf97/0x46e0 fs/ext4/inode.c:2907 ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3019 do_writepages+0x32e/0x550 mm/page-writeback.c:2554 __writeback_single_inode+0x133/0x11a0 fs/fs-writeback.c:1749 writeback_sb_inodes+0x944/0x1970 fs/fs-writeback.c:2040 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2117 wb_writeback+0x46a/0xb70 fs/fs-writeback.c:2228 wb_check_old_data_flush fs/fs-writeback.c:2332 [inline] wb_do_writeback fs/fs-writeback.c:2385 [inline] wb_workfn+0xb52/0xf60 fs/fs-writeback.c:2413 process_one_work kernel/workqueue.c:3275 [inline] process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: jbd2_handle --> &ei->xattr_sem --> &sbi->s_writepages_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&sbi->s_writepages_rwsem); lock(&ei->xattr_sem); lock(&sbi->s_writepages_rwsem); lock(jbd2_handle); *** DEADLOCK *** 4 locks held by kworker/u8:11/1186: #0: ffff88801f6af138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline] #0: ffff88801f6af138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358 #1: ffffc90006487c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline] #1: ffffc90006487c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358 #2: ffff888036d540d0 (&type->s_umount_key#32){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:565 #3: ffff888036d52c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: percpu_down_read include/linux/percpu-rwsem.h:77 [inline] #3: ffff888036d52c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1813 [inline] #3: ffff888036d52c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x205/0x3b0 fs/ext4/inode.c:3018 stack backtrace: CPU: 1 UID: 0 PID: 1186 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 wait_transaction_locked+0x1c2/0x280 fs/jbd2/transaction.c:151 add_transaction_credits fs/jbd2/transaction.c:222 [inline] start_this_handle+0x7dc/0x2290 fs/jbd2/transaction.c:403 jbd2__journal_start+0x2c0/0x5b0 fs/jbd2/transaction.c:501 __ext4_journal_start_sb+0x203/0x620 fs/ext4/ext4_jbd2.c:114 __ext4_journal_start fs/ext4/ext4_jbd2.h:242 [inline] ext4_do_writepages+0xf97/0x46e0 fs/ext4/inode.c:2907 ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3019 do_writepages+0x32e/0x550 mm/page-writeback.c:2554 __writeback_single_inode+0x133/0x11a0 fs/fs-writeback.c:1749 writeback_sb_inodes+0x944/0x1970 fs/fs-writeback.c:2040 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2117 wb_writeback+0x46a/0xb70 fs/fs-writeback.c:2228 wb_check_old_data_flush fs/fs-writeback.c:2332 [inline] wb_do_writeback fs/fs-writeback.c:2385 [inline] wb_workfn+0xb52/0xf60 fs/fs-writeback.c:2413 process_one_work kernel/workqueue.c:3275 [inline] process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- 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.