On Sat, 2024-07-06 at 21:37 -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 1dd28064d416 Merge tag 'integrity-v6.10-fix' of ssh://ra.k.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16814d76980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=1ace69f521989b1f > dashboard link: https://syzkaller.appspot.com/bug?extid=b568ba42c85a332a88ee > compiler: Debian clang version 15.0.6, 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/20c723869b92/disk-1dd28064.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/c2a9a7382516/vmlinux-1dd28064.xz > kernel image: https://storage.googleapis.com/syzbot-assets/9872fe6f2853/bzImage-1dd28064.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+b568ba42c85a332a88ee@xxxxxxxxxxxxxxxxxxxxxxxxx > > INFO: task syz.0.2871:13167 blocked for more than 143 seconds. > Not tainted 6.10.0-rc6-syzkaller-00212-g1dd28064d416 #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz.0.2871 state:D stack:26704 pid:13167 tgid:13165 ppid:10304 flags:0x00000004 > Call Trace: > <TASK> > context_switch kernel/sched/core.c:5408 [inline] > __schedule+0x1796/0x49d0 kernel/sched/core.c:6745 > __schedule_loop kernel/sched/core.c:6822 [inline] > schedule+0x14b/0x320 kernel/sched/core.c:6837 > schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6894 > __mutex_lock_common kernel/locking/mutex.c:684 [inline] > __mutex_lock+0x6a4/0xd70 kernel/locking/mutex.c:752 > nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:632 > nfsd_umount+0x43/0xd0 fs/nfsd/nfsctl.c:1412 > deactivate_locked_super+0xc4/0x130 fs/super.c:473 > put_fs_context+0x94/0x780 fs/fs_context.c:516 > fscontext_release+0x65/0x80 fs/fsopen.c:73 > __fput+0x24a/0x8a0 fs/file_table.c:422 > task_work_run+0x24f/0x310 kernel/task_work.c:180 > resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] > exit_to_user_mode_loop kernel/entry/common.c:114 [inline] > exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] > __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] > syscall_exit_to_user_mode+0x168/0x360 kernel/entry/common.c:218 > do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f11fe775bd9 > RSP: 002b:00007f11ff494048 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 > RAX: 0000000000000000 RBX: 00007f11fe903f60 RCX: 00007f11fe775bd9 > RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000003 > RBP: 00007f11fe7e4aa1 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 000000000000000b R14: 00007f11fe903f60 R15: 00007ffc04bba328 > </TASK> > > Showing all locks held in the system: > 1 lock held by khungtaskd/30: > #0: ffffffff8e333f20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline] > #0: ffffffff8e333f20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline] > #0: ffffffff8e333f20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6614 > 3 locks held by kworker/u8:4/66: > #0: ffff888015089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3223 [inline] > #0: ffff888015089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3329 > #1: ffffc900020afd00 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3224 [inline] > #1: ffffc900020afd00 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3329 > #2: ffffffff8e3391c0 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x4c/0x530 kernel/rcu/tree.c:4448 > 4 locks held by udevd/4534: > #0: ffff88805a0fdd58 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb7/0xd60 fs/seq_file.c:182 > #1: ffff88806542ec88 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154 > #2: ffff88805af532d8 (kn->active#5){++++}-{0:0}, at: kernfs_seq_start+0x72/0x3b0 fs/kernfs/file.c:155 > #3: ffff8880686c90e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1009 [inline] > #3: ffff8880686c90e8 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17d/0x340 drivers/base/core.c:2743 > 2 locks held by getty/4842: > #0: ffff88802f9d10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 > #1: ffffc9000312b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b5/0x1e10 drivers/tty/n_tty.c:2211 > 3 locks held by kworker/u9:10/5101: > #0: ffff88802e1fa148 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3223 [inline] > #0: ffff88802e1fa148 ((wq_completion)hci2){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3329 > #1: ffffc90003827d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3224 [inline] > #1: ffffc90003827d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3329 > #2: ffff888020eb4d88 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1ec/0x400 net/bluetooth/hci_sync.c:322 > 2 locks held by syz.4.2691/12623: > #0: ffffffff8f63ad70 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 > #1: ffffffff8e5fff48 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_nl_listener_set_doit+0x12d/0x1a90 fs/nfsd/nfsctl.c:1940 > 2 locks held by syz.0.2871/13167: > #0: ffff88804e1920e0 (&type->s_umount_key#77){++++}-{3:3}, at: __super_lock fs/super.c:56 [inline] > #0: ffff88804e1920e0 (&type->s_umount_key#77){++++}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline] > #0: ffff88804e1920e0 (&type->s_umount_key#77){++++}-{3:3}, at: deactivate_super+0xb5/0xf0 fs/super.c:505 > #1: ffffffff8e5fff48 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:632 Above there are two tasks that are holding/blocked on the nfsd_mutex. The first is the stuck thread. The second is a task that took it in nfsd_nl_listener_set_doit. I don't see a way to exit that function without releasing that mutex, so it seems likely that thread is stuck too for some reason. Unfortunately, we don't have a stack trace from that task, so I can't tell what it's doing. > 1 lock held by udevd/14823: > 2 locks held by syz-executor/15993: > #0: ffffffff8f5d4908 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline] > #0: ffffffff8f5d4908 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x842/0x1180 net/core/rtnetlink.c:6632 > #1: ffffffff8e3392f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline] > #1: ffffffff8e3392f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x451/0x830 kernel/rcu/tree_exp.h:939 > 1 lock held by syz.4.3895/16063: > #0: ffff88804e1920e0 (&type->s_umount_key#77){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline] > #0: ffff88804e1920e0 (&type->s_umount_key#77){++++}-{3:3}, at: super_lock+0x27c/0x400 fs/super.c:120 > 4 locks held by kvm-nx-lpage-re/16077: > #0: ffffffff8e361f28 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock include/linux/cgroup.h:368 [inline] > #0: ffffffff8e361f28 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_attach_task_all+0x27/0xe0 kernel/cgroup/cgroup-v1.c:61 > #1: ffffffff8e1ce5b0 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_attach_lock+0x11/0x40 kernel/cgroup/cgroup.c:2413 > #2: ffffffff8e362110 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_attach_task_all+0x31/0xe0 kernel/cgroup/cgroup-v1.c:62 > #3: ffffffff8e3392f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline] > #3: ffffffff8e3392f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x381/0x830 kernel/rcu/tree_exp.h:939 > > ============================================= > > NMI backtrace for cpu 1 > CPU: 1 PID: 30 Comm: khungtaskd Not tainted 6.10.0-rc6-syzkaller-00212-g1dd28064d416 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 > nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113 > nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62 > trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline] > check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline] > watchdog+0xfde/0x1020 kernel/hung_task.c:379 > kthread+0x2f0/0x390 kernel/kthread.c:389 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > </TASK> > Sending NMI from CPU 1 to CPUs 0: > NMI backtrace for cpu 0 > CPU: 0 PID: 1109 Comm: kworker/u8:6 Not tainted 6.10.0-rc6-syzkaller-00212-g1dd28064d416 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 > Workqueue: writeback wb_workfn (flush-8:0) > RIP: 0010:bio_add_page+0xb7/0x840 block/bio.c:1118 > Code: 05 00 00 8b 5d 00 45 89 f4 41 f7 d4 89 df 44 89 e6 e8 dd 6f 11 fd 44 39 e3 76 0a e8 13 6e 11 fd e9 20 04 00 00 48 89 6c 24 28 <49> 8d 5f 70 48 89 d8 48 c1 e8 03 48 89 44 24 30 42 0f b6 04 28 84 > RSP: 0018:ffffc900045ce610 EFLAGS: 00000213 > RAX: 0000000000000000 RBX: 000000000000a000 RCX: ffff888022311e00 > RDX: ffff888022311e00 RSI: 00000000ffffefff RDI: 000000000000a000 > RBP: ffff88802eb37a28 R08: ffffffff8484b8a3 R09: 1ffffd4000090b30 > R10: dffffc0000000000 R11: fffff94000090b31 R12: 00000000ffffefff > R13: dffffc0000000000 R14: 0000000000001000 R15: ffff88802eb37a00 > FS: 0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000001b30e11ff8 CR3: 000000000e132000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <NMI> > </NMI> > <TASK> > bio_add_folio+0x52/0x80 block/bio.c:1160 > io_submit_add_bh fs/ext4/page-io.c:422 [inline] > ext4_bio_write_folio+0x1691/0x1da0 fs/ext4/page-io.c:560 > mpage_submit_folio+0x1af/0x230 fs/ext4/inode.c:1869 > mpage_process_page_bufs+0x6c9/0x8d0 fs/ext4/inode.c:1982 > mpage_prepare_extent_to_map+0xec7/0x1c80 fs/ext4/inode.c:2490 > ext4_do_writepages+0xc52/0x3d40 fs/ext4/inode.c:2632 > ext4_writepages+0x213/0x3c0 fs/ext4/inode.c:2768 > do_writepages+0x359/0x870 mm/page-writeback.c:2656 > __writeback_single_inode+0x165/0x10b0 fs/fs-writeback.c:1651 > writeback_sb_inodes+0x99c/0x1380 fs/fs-writeback.c:1947 > __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2018 > wb_writeback+0x495/0xd40 fs/fs-writeback.c:2129 > wb_check_old_data_flush fs/fs-writeback.c:2233 [inline] > wb_do_writeback fs/fs-writeback.c:2286 [inline] > wb_workfn+0xba1/0x1090 fs/fs-writeback.c:2314 > process_one_work kernel/workqueue.c:3248 [inline] > process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3329 > worker_thread+0x86d/0xd50 kernel/workqueue.c:3409 > kthread+0x2f0/0x390 kernel/kthread.c:389 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > </TASK> > > > --- > 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 -- Jeff Layton <jlayton@xxxxxxxxxx>
