On Tue, Oct 1, 2024 at 12:24 PM syzbot <syzbot+217a976dc26ef2fa8711@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: e32cde8d2bd7 Merge tag 'sched_ext-for-6.12-rc1-fixes-1' of.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=12e8bdd0580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=1b5201b91035a876 > dashboard link: https://syzkaller.appspot.com/bug?extid=217a976dc26ef2fa8711 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/a585cdb91cda/disk-e32cde8d.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/dbeec5d7b296/vmlinux-e32cde8d.xz > kernel image: https://storage.googleapis.com/syzbot-assets/000fd790e08a/bzImage-e32cde8d.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+217a976dc26ef2fa8711@xxxxxxxxxxxxxxxxxxxxxxxxx > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 5296 at fs/fuse/file.c:1989 fuse_write_file_get fs/fuse/file.c:1989 [inline] > WARNING: CPU: 0 PID: 5296 at fs/fuse/file.c:1989 fuse_write_file_get fs/fuse/file.c:1986 [inline] > WARNING: CPU: 0 PID: 5296 at fs/fuse/file.c:1989 fuse_writepages+0x497/0x5a0 fs/fuse/file.c:2368 > Modules linked in: > CPU: 0 UID: 0 PID: 5296 Comm: kworker/u8:8 Not tainted 6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > Workqueue: writeback wb_workfn (flush-0:52) > RIP: 0010:fuse_write_file_get fs/fuse/file.c:1989 [inline] > RIP: 0010:fuse_write_file_get fs/fuse/file.c:1986 [inline] > RIP: 0010:fuse_writepages+0x497/0x5a0 fs/fuse/file.c:2368 > Code: 00 00 00 44 89 f8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc e8 79 b6 90 fe 48 8b 7c 24 08 e8 af 6f 27 08 e8 6a b6 90 fe 90 <0f> 0b 90 41 bf fb ff ff ff eb 8b e8 59 b6 90 fe 48 8b 7c 24 18 be > RSP: 0018:ffffc900044ff4a8 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: ffffc900044ff4f8 RCX: 0000000000000000 > RDX: ffff88802d42da00 RSI: ffffffff82fcd286 RDI: 0000000000000001 > RBP: ffff88805c994aa0 R08: 0000000000000000 R09: ffffed100b9329d7 > R10: ffff88805c994ebb R11: 0000000000000003 R12: ffffc900044ff840 > R13: ffff88805c994880 R14: ffff88805f330000 R15: ffff88805c994d50 > FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000020055000 CR3: 000000005df4a000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > do_writepages+0x1a3/0x7f0 mm/page-writeback.c:2683 > __writeback_single_inode+0x166/0xfa0 fs/fs-writeback.c:1658 > writeback_sb_inodes+0x603/0xfa0 fs/fs-writeback.c:1954 > wb_writeback+0x199/0xb50 fs/fs-writeback.c:2134 > wb_do_writeback fs/fs-writeback.c:2281 [inline] > wb_workfn+0x294/0xbc0 fs/fs-writeback.c:2321 > process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229 > process_scheduled_works kernel/workqueue.c:3310 [inline] > worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391 > kthread+0x2c1/0x3a0 kernel/kthread.c:389 > ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > </TASK> > #syz dup: [syzbot] [fuse?] WARNING in fuse_write_file_get (2) This is the same warning reported in https://lore.kernel.org/linux-fsdevel/66fbae38.050a0220.6bad9.0051.GAE@xxxxxxxxxx/T/#u The warning is complaining about this WARN_ON here https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/fuse/file.c#n1989. I think this warning can get triggered if there's a race between a write() and a close() where the page is dirty in the cache after the release has happened. Then when writeback (eg fuse_writepages()) is triggered, we hit this warning. (this possibility has always existed, it was surfaced after this refactoring commit 4046d3adcca4: "move fuse file initialization to wpa allocation time" but the actual logic hasn't been changed). I think we can address this by instead calling "data.ff = __fuse_write_file_get(fi);" in fuse_writepages(). I'll submit a fix for this to Miklos's tree. Thanks, Joanne > > --- > 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@xxxxxxxxxxxxxxxx. > > 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 >
