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Wed, 27 Aug 2025 06:45:27 -0700 (PDT) MIME-Version: 1.0 References: <68a841d7.050a0220.37038e.0051.GAE@google.com> In-Reply-To: <68a841d7.050a0220.37038e.0051.GAE@google.com> From: Aleksandr Nogikh Date: Wed, 27 Aug 2025 15:45:16 +0200 X-Gm-Features: Ac12FXy3XsS3r_1Xsoljd22xWwY_l_Rgh701RqGb2u2OIv6ofdVJaEbx_TPotDk Message-ID: Subject: Re: [syzbot] [fs?] [mm?] linux-next test error: WARNING in __folio_start_writeback To: syzbot , joannelkoong@gmail.com, David Hildenbrand , mszeredi@redhat.com Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-next@vger.kernel.org, sfr@canb.auug.org.au, syzkaller-bugs@googlegroups.com, willy@infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: ua5dp1k97fdmoypb66w3d6sq6w4qdn4b X-Rspam-User: X-Rspamd-Queue-Id: B4E3BC001A X-Rspamd-Server: rspam01 X-HE-Tag: 1756302328-319166 X-HE-Meta: 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 ybw6+Tj3 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 Ue4ZYNIa Ph9A0DKJyDl73PHNBxQKA2cHM/Bz8Hrnwgu1aqXd3MWCvjnXQJ9RRsJdv1WXzZfe7eBxwtglw2MnHkLSFMSgVMUjF0S1Lgag X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: I've bisected the problem to the following commit: commit 167f21a81a9c4dbd6970a4ee3853aecad405fa7f (HEAD) Author: Joanne Koong Date: Mon Jul 7 16:46:06 2025 -0700 mm: remove BDI_CAP_WRITEBACK_ACCT There are no users of BDI_CAP_WRITEBACK_ACCT now that fuse doesn't do its own writeback accounting. This commit removes BDI_CAP_WRITEBACK_ACCT. Joanne Koong, could you please take a look at the syzbot report below? On Fri, Aug 22, 2025 at 12:09=E2=80=AFPM syzbot wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 0f4c93f7eb86 Add linux-next specific files for 20250822 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=3D172c07bc58000= 0 > kernel config: https://syzkaller.appspot.com/x/.config?x=3D21eed27c0dead= b92 > dashboard link: https://syzkaller.appspot.com/bug?extid=3D0630e71306742d4= b2aea > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f604= 9-1~exp1~20250616065826.132), Debian LLD 20.1.7 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/669ede8f5d66/dis= k-0f4c93f7.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/50feda89fe89/vmlinu= x-0f4c93f7.xz > kernel image: https://storage.googleapis.com/syzbot-assets/317a0d3516fb/b= zImage-0f4c93f7.xz > > IMPORTANT: if you fix the issue, please add the following tag to the comm= it: > Reported-by: syzbot+0630e71306742d4b2aea@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > WARNING: ./include/linux/backing-dev.h:243 at inode_to_wb include/linux/b= acking-dev.h:239 [inline], CPU#1: kworker/u8:6/2949 > WARNING: ./include/linux/backing-dev.h:243 at __folio_start_writeback+0x9= d5/0xb70 mm/page-writeback.c:3027, CPU#1: kworker/u8:6/2949 > Modules linked in: > CPU: 1 UID: 0 PID: 2949 Comm: kworker/u8:6 Not tainted syzkaller #0 PREEM= PT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS G= oogle 07/12/2025 > Workqueue: writeback wb_workfn (flush-8:0) > RIP: 0010:inode_to_wb include/linux/backing-dev.h:239 [inline] > RIP: 0010:__folio_start_writeback+0x9d5/0xb70 mm/page-writeback.c:3027 > Code: 28 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 ce a2 29 0= 0 49 8b 07 25 ff 3f 00 00 e9 1b fa ff ff e8 7c 04 c6 ff 90 <0f> 0b 90 e9 d6= fb ff ff e8 6e 04 c6 ff 48 c7 c7 a0 f8 5f 8e 4c 89 > RSP: 0018:ffffc9000bb06ea0 EFLAGS: 00010293 > RAX: ffffffff81fad344 RBX: ffffea00050de8c0 RCX: ffff88802ee29e00 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: ffffc9000bb07010 R08: ffffc9000bb06f97 R09: 0000000000000000 > R10: ffffc9000bb06f80 R11: fffff52001760df3 R12: ffffea00050de8c8 > R13: 0000000000000000 R14: ffff888023060880 R15: ffff888023060660 > FS: 0000000000000000(0000) GS:ffff8881258c3000(0000) knlGS:0000000000000= 000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f7354907000 CR3: 000000000e338000 CR4: 00000000003526f0 > Call Trace: > > __block_write_full_folio+0x75f/0xe10 fs/buffer.c:1928 > blkdev_writepages+0xd1/0x170 block/fops.c:484 > do_writepages+0x32e/0x550 mm/page-writeback.c:2604 > __writeback_single_inode+0x145/0xff0 fs/fs-writeback.c:1680 > writeback_sb_inodes+0x6c7/0x1010 fs/fs-writeback.c:1976 > __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2047 > wb_writeback+0x44f/0xaf0 fs/fs-writeback.c:2158 > wb_check_old_data_flush fs/fs-writeback.c:2262 [inline] > wb_do_writeback fs/fs-writeback.c:2315 [inline] > wb_workfn+0xaef/0xef0 fs/fs-writeback.c:2343 > process_one_work kernel/workqueue.c:3236 [inline] > process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 > worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 > kthread+0x711/0x8a0 kernel/kthread.c:463 > ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > > > --- > 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 >