From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f78.google.com (mail-ot1-f78.google.com [209.85.210.78]) (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 90E4E282F34 for ; Mon, 17 Aug 2026 02:15:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786932933; cv=none; b=tEKQkTYyfjeEWoOrDrGm470mud0IFCg9w4mm8yRzPA51EyvQExbGso5aSErr5zxlnMrvTa8Ex3fLLBvIKUt6ntqnD+Sl3sRCMWcSevtNMKpSry6bNSkcgw0oZBusn2iB8YW8hG8jaEen3+dgasDwJyEW+qIgn5yfHmuHa+P1WOM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786932933; c=relaxed/simple; bh=mNkSF1ZcoMn+ga59hTYTohTkP7ZiRYj4ZunpmVCfzo4=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=Cs8EaSMs04RVIGgMYJYTWVfvi8p8c4CyuJGy9P7maEa120jGRd0xvj2pzLk6oByhyEZJy5RrFwrYJEPFmCPpA2IaBcbTa6F1pnwGzZqjLehIEfJblhwZckDdSuvcaitDvV4awakakz2z8qn8e5GTgsxadOTeLn0wQTt8I+MZfN8= 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=209.85.210.78 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-f78.google.com with SMTP id 46e09a7af769-7eb89852728so2179305a34.3 for ; Sun, 16 Aug 2026 19:15:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786932930; x=1787537730; 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=/VsnQs59f+hlKY30my1HgtF1nrtn+p2VRuv+FAV5UAQ=; b=GJIUDwcvFwn2IXOzvYkvhwne3v3S/91Es+7tXGmrUpYRdwQkQtZo1if1NPzYRnK8Ei 2BY/j9h5JpWwvlve92aD039KZcf/QKFhRySNqvDEgj34FWyFfhuMAbwngwLCFPDayL96 P91sndfp3TzJ9INDdfiuI+6hi2pG6j6huh2FymK55rXMywDF38LLtSP+VbS7aJjc2JHt QfB2HMywEK+4GAPBLpZbeMzdeLT4f8ghvRRPKuFxaIKp2xeCDBAKiHOgnxD2HrCX3uX5 os0BTScGlgJcqCFPCZBzBrApi6jT8Gfd+JO1vzty5l+tymBuC//l2PFPnUylLrLP6bEH N9UA== X-Forwarded-Encrypted: i=1; AHgh+Rpww2Db0eqiZ2qEbvlpNsrQLUVsG+Y02dll1JGhW6RgBkOCMLs7f6UeuX8lo21FL0F9d/QBlcoOOe9EuNc=@vger.kernel.org X-Gm-Message-State: AOJu0YzkV38FEPEgvMc3psP+zZtkdU6PigSd7dpJ0QgIqFBLOxuhv+AD crSzUvaMnGzKuipQ3uNn1f2RQtCfqjO35MSTwJ1sOauS03WT0BO22ECOpal0TLRApnw55SmV1al TGEhgENFa25Lku/Zyc4j+Zkc5HvIlYfn2n08tkyph/8lA8GnViJqk8AVFiys= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1986:b0:6a3:c5:30ca with SMTP id 006d021491bc7-6b0d6919fc7mr19587446eaf.31.1786932930395; Sun, 16 Aug 2026 19:15:30 -0700 (PDT) Date: Sun, 16 Aug 2026 19:15:30 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a826ec2.dbb3a75c.20434b.003e.GAE@google.com> Subject: [syzbot] [exfat?] WARNING in fat12_ent_put From: syzbot To: hirofumi@mail.parknet.co.jp, linkinjeon@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, sj1557.seo@samsung.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 28d012efb432 Add linux-next specific files for 20260812 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=104eec79580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5a13c7bc480b5c3f dashboard link: https://syzkaller.appspot.com/bug?extid=e64c6472a3d96a75172a 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/de882be6df4b/disk-28d012ef.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/412cb9fb7e2d/vmlinux-28d012ef.xz kernel image: https://storage.googleapis.com/syzbot-assets/9d7096c27f1b/bzImage-28d012ef.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+e64c6472a3d96a75172a@syzkaller.appspotmail.com Buffer I/O error on dev loop0, logical block 1, lost sync page write ------------[ cut here ]------------ !buffer_uptodate(bh) WARNING: fs/buffer.c:991 at mark_buffer_dirty+0x299/0x410 fs/buffer.c:991, CPU#1: syz.0.824/10458 Modules linked in: CPU: 1 UID: 0 PID: 10458 Comm: syz.0.824 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:mark_buffer_dirty+0x299/0x410 fs/buffer.c:991 Code: 4c 89 f7 e8 49 11 d8 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 34 53 fb ff e8 9f a3 69 ff eb 8c e8 98 a3 69 ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 8a a3 69 ff 90 0f 0b 90 e9 cf fd ff ff RSP: 0018:ffffc900065273f8 EFLAGS: 00010287 RAX: ffffffff825e07c8 RBX: ffff888056e9e460 RCX: 0000000000080000 RDX: ffffc90003f49000 RSI: 0000000000001234 RDI: 0000000000001235 RBP: dffffc0000000001 R08: ffff888056e9e467 R09: 1ffff1100add3c8c R10: dffffc0000000000 R11: ffffed100add3c8d R12: dffffc0000000000 R13: 1ffff92000ca4eb6 R14: ffffc900065275b0 R15: ffff888050e4ccf8 FS: 00007fe3dc5436c0(0000) GS:ffff888124dfc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e6edff8 CR3: 000000007c12c000 CR4: 00000000003526f0 Call Trace: mmb_mark_buffer_dirty+0x2c/0x1f0 fs/buffer.c:624 fat12_ent_put+0x1b7/0x2f0 fs/fat/fatent.c:173 fat_ent_write+0xb8/0x190 fs/fat/fatent.c:422 fat_chain_add+0x409/0x8e0 fs/fat/misc.c:140 fat_add_cluster fs/fat/inode.c:113 [inline] __fat_get_block fs/fat/inode.c:155 [inline] fat_get_block+0x768/0xae0 fs/fat/inode.c:190 __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2030 block_write_begin fs/buffer.c:2144 [inline] cont_write_begin+0x71b/0xac0 fs/buffer.c:2506 fat_write_begin+0x7a/0x150 fs/fat/inode.c:230 cont_expand_zero fs/buffer.c:2434 [inline] cont_write_begin+0x2d6/0xac0 fs/buffer.c:2496 fat_write_begin+0x7a/0x150 fs/fat/inode.c:230 generic_cont_expand_simple+0x146/0x210 fs/buffer.c:2397 fat_cont_expand+0x61/0x1f0 fs/fat/file.c:226 fat_fallocate+0x22f/0x2f0 fs/fat/file.c:304 vfs_fallocate+0x65a/0x7e0 fs/open.c:338 ksys_fallocate fs/open.c:362 [inline] __do_sys_fallocate fs/open.c:367 [inline] __se_sys_fallocate fs/open.c:365 [inline] __x64_sys_fallocate+0xbf/0x110 fs/open.c:365 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: 0033:0x7fe3db59e0d9 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:00007fe3dc543028 EFLAGS: 00000246 ORIG_RAX: 000000000000011d RAX: ffffffffffffffda RBX: 00007fe3db825fa0 RCX: 00007fe3db59e0d9 RDX: 0000000000000009 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00007fe3db635024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe3db826038 R14: 00007fe3db825fa0 R15: 00007fffaef17d98 --- 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