From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.167.200 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793624992; b=LS1Hto5z5ZV2iH/onMvX1YSDAiIhk9kjabiDkei4D3Dgm/DhjqilTNMumZilysgpn+g2 Z4R6qQDu0tvC3WOF39bJzgtyD5V7UcUITg9uq2L8MU8eWxciRYIwpl7bV6hyDmwsryPfs jGDI3vWxAmsuZf25LGYSg9ZMNs8OUwVQQcW0brknwzMlMNRlFjg6bzzJKG9wEXgguKNOY 2mBQNro7kq7Xw6HWzch11VD4i09FYekIklhPmsjrfKHZ2udz/uKb0H77h+GhhJ0mwJemG NGI+ym6qcMPXyUjJqqife2SUvyDxm34gaAskVvzbux5CLtV+UBycBlWEziPQlqyNIkQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793624992; h=DMARC-Filter:Received:X-Google-DKIM-Signature:X-Forwarded-Encrypted: X-Gm-Message-State:MIME-Version:X-Received:Date: X-Google-Appengine-App-Id:X-Google-Appengine-App-Id-Alias:Message-ID: Subject:From:To:Content-Type; bh=jqBUz6nIoIfKS3gUvjdI9+AWIpUhKAXXkzURXSQOsdU=; b=0MtuLHKaqraFEKYFj5FoA5Oage729Gg6oWhiYzyLbQSdPNd2y7aQuu3X56lhcOV7nQmB EEaag74f6o2OPAgWhXvwhxpKqshaXHp5OWJqmVHSjVbND8meos4drjPCkcu5x1ulJwP/1 YEJd07ifWYx4GncbUgtGkUK1LSzjXvKOJGxeY7G1eaj7GKB+5cQNyI3BXxT/nTc1T8LK1 XeS5SXO0zOkNXCTdVWNESDL5QAumZP2SezFzw+r2UPpnBdRHYVRKQZgWH+vqe4njsKQHm xdBTDaQ3BVclLafzr0NPU9p2ZIExigIb79K9hZOtA6yr/CjX+dGtthfbMhKqCBl7t4w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.remote-ip=209.85.167.200 Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC57E606A334 for ; Mon, 2 Nov 2026 13:09:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org EC57E606A334 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-f200.google.com with SMTP id 5614622812f47-4ab8b4887d4so2714658b6e.1 for ; Mon, 02 Nov 2026 05:09:51 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793624991; x=1794229791; 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=jqBUz6nIoIfKS3gUvjdI9+AWIpUhKAXXkzURXSQOsdU=; b=cPKsgk96VieZignveodEnDEYEiGYbtB/LCYBJy56mRkuZWh5O2S6gEz7qZPy43nFJi EbcdjAX4ZbR21cbhVLkspePexs2+u5gsx6my7YqhzIfqoZu5b5sdJgRgamjhLEZvzNFF ZeaIxfQe99XLJjLVbt1pBU1/xRRPs3g7e5C6qB/wLEt43bLi8YtUkfD+GpTb1IsTfla1 Ji0i441IgHC7dBXO1ENss+AxjYguoISGAySEP5nviZ8VPOH2PbD9lb+DVMFXnTVUsGAm HRf5PNYj5HubMRiiqqpgLBgYf6tXMPCWLAXn/nNa/BeCowxZ17a6MXYHrbkSXkQDhxjC zy9g== X-Forwarded-Encrypted: i=1; AKwUvBzKlqrvS4MxaiA3IDdzX+1TnCwCD6hxy1lEWjwqRV6konsczMGgObH6G/iw4BQJqty/PRWl2gpO8vY9AIY=@vger.kernel.org X-Gm-Message-State: AFq9FYJHCi23E86WeeIkLd8LEq5cuBx+Ce5KSOWs3QZ86vLnd18TAeMo DEXYELo1oGmUzr02aNDn3s10v/rkIw9k3fcyBkHU+hmhRYIKyjmM1EfYmTnn6eIG0ecFzsH9aTO gSxpEmIbrnrRUdwyOKhAMEpVCAmhbLAFScj9gLUhCKccId1JKaA5TrX97M7g= X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Received: by 2002:a05:6808:1310:b0:4f4:2b4c:d66a with SMTP id 5614622812f47-5640dcea140mr6263705b6e.12.1793624990946; Mon, 02 Nov 2026 05:09:50 -0800 (PST) Date: Mon, 02 Nov 2026 05:09:50 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ae88b9e.64e51036.15cf6a.0027.GAE@google.com> Subject: [syzbot] [btrfs?] WARNING in btrfs_release_global_block_rsv (3) From: syzbot To: dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, mason@kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 36aad21d50d1 Merge tag 'ksmbd-for-7.4-rc1-part2' of git://.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13724959580000 kernel config: https://syzkaller.appspot.com/x/.config?x=dc4462df6d1062fe dashboard link: https://syzkaller.appspot.com/bug?extid=7ec60f4482abeecb0fd8 compiler: Debian clang version 22.1.8 (1~deb13u4), 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/96a3448f37dc/disk-36aad21d.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/0b79495726f5/vmlinux-36aad21d.xz kernel image: https://storage.googleapis.com/syzbot-assets/4480be87f78d/bzImage-36aad21d.xz AI-generated root cause summary: In Btrfs, when an extent is freed and reallocated with a smaller size before its delayed refs are processed, update_existing_head_ref() overwrites existing->num_bytes with the new size before adjusting checksum deletion accounting. When existing->total_ref_mod transitions from negative to non-negative, btrfs_delayed_refs_rsv_release() calculates and releases fewer csum leaves than were originally accounted in add_delayed_ref_head(). This permanently leaks delayed_refs_rsv size and reserved space, leading to metadata space exhaustion (premature -ENOSPC) during runtime and triggering a WARNING on unmount in btrfs_release_global_block_rsv(). full analysis: https://syzkaller.appspot.com/x/ai_root_cause?x=7ec60f4482abeecb0fd8 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7ec60f4482abeecb0fd8@syzkaller.appspotmail.com BTRFS info (device loop6): last unmount of filesystem db05bf05-c4f4-4d41-ba1f-eb57295b561b ------------[ cut here ]------------ fs_info->delayed_refs_rsv.reserved > 0 WARNING: fs/btrfs/block-rsv.c:481 at btrfs_release_global_block_rsv+0x2e4/0x300 fs/btrfs/block-rsv.c:481, CPU#1: syz-executor/6147 Modules linked in: CPU: 1 UID: 0 PID: 6147 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026 RIP: 0010:btrfs_release_global_block_rsv+0x2e4/0x300 fs/btrfs/block-rsv.c:481 Code: 0f 0b 90 e9 c1 fe ff ff e8 69 cd 84 fd 90 0f 0b 90 e9 eb fe ff ff e8 5b cd 84 fd 90 0f 0b 90 e9 15 ff ff ff e8 4d cd 84 fd 90 <0f> 0b 90 e9 46 ff ff ff e8 3f cd 84 fd 90 0f 0b 90 e9 69 ff ff ff RSP: 0018:ffffc90006717ad0 EFLAGS: 00010293 RAX: ffffffff84430bd3 RBX: ffff8880636e4768 RCX: ffff888031809f40 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff8880636e42b0 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffffbfff21ab138 R12: ffff8880636e4000 R13: 0000000000000000 R14: 0000000000008000 R15: dffffc0000000000 FS: 000055557537f500(0000) GS:ffff888124816000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2f2de04e00 CR3: 000000003d9c0000 CR4: 00000000003526f0 Call Trace: btrfs_free_block_groups+0xdc2/0x1040 fs/btrfs/block-group.c:4444 close_ctree+0x7d1/0x1200 fs/btrfs/disk-io.c:4575 generic_shutdown_super+0x140/0x2d0 fs/super.c:723 kill_anon_super+0x3b/0x70 fs/super.c:1315 btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2139 deactivate_locked_super+0xbe/0x110 fs/super.c:558 cleanup_mnt+0x204/0x2a0 fs/namespace.c:1396 task_work_run+0x1d9/0x260 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f43e2c70797 Code: a2 c7 05 5c 9f 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007ffe17fa6818 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f43e2d05f93 RCX: 00007f43e2c70797 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe17fa68d0 RBP: 00007ffe17fa68d0 R08: 00007ffe17fa78d0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe17fa7960 R13: 00007f43e2d05f93 R14: 000000000003637c R15: 00007ffe17fa79a0 --- 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