Re: [syzbot] [net?] INFO: task hung in tls_sw_sendpage (3)

Eric Dumazet
2023-02-27T20:35:58Z

On Mon, Feb 27, 2023 at 9:33 PM syzbot
<syzbot+9c0268252b8ef967c62e@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: d9fc1511728c Merge tag 'net-6.2-rc4' of git://git.kernel.o..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1243daa6480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2b6ecad960fc703e
> dashboard link: https://syzkaller.appspot.com/bug?extid=9c0268252b8ef967c62e
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/7e45a73db0f3/disk-d9fc1511.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/09ac811286ca/vmlinux-d9fc1511.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/0985b60a6dbc/bzImage-d9fc1511.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9c0268252b8ef967c62e@syzkaller.appspotmail.com
>
> INFO: task syz-executor.5:30321 blocked for more than 143 seconds.
> Not tainted 6.2.0-rc3-syzkaller-00165-gd9fc1511728c #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor.5 state:D
> stack:26480 pid:30321 ppid:5106 flags:0x00004004
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5293 [inline]
> __schedule+0xb8a/0x5450 kernel/sched/core.c:6606
> schedule+0xde/0x1b0 kernel/sched/core.c:6682
> schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6741
> __mutex_lock_common kernel/locking/mutex.c:679 [inline]
> __mutex_lock+0xa48/0x1360 kernel/locking/mutex.c:747
> tls_sw_sendpage+0x83/0xe0 net/tls/tls_sw.c:1278
> inet_sendpage+0xd4/0x140 net/ipv4/af_inet.c:844
> kernel_sendpage.part.0+0x1d5/0x700 net/socket.c:3555
> kernel_sendpage net/socket.c:3552 [inline]
> sock_sendpage+0xe3/0x140 net/socket.c:1054
> pipe_to_sendpage+0x2b1/0x380 fs/splice.c:361
> splice_from_pipe_feed fs/splice.c:415 [inline]
> __splice_from_pipe+0x449/0x8a0 fs/splice.c:559
> splice_from_pipe fs/splice.c:594 [inline]
> generic_splice_sendpage+0xd8/0x140 fs/splice.c:743
> do_splice_from fs/splice.c:764 [inline]
> direct_splice_actor+0x114/0x180 fs/splice.c:931
> splice_direct_to_actor+0x335/0x8a0 fs/splice.c:886
> do_splice_direct+0x1ab/0x280 fs/splice.c:974
> do_sendfile+0xb19/0x1270 fs/read_write.c:1255
> __do_sys_sendfile64 fs/read_write.c:1323 [inline]
> __se_sys_sendfile64 fs/read_write.c:1309 [inline]
> __x64_sys_sendfile64+0x1d0/0x210 fs/read_write.c:1309
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f2463e8c0c9
> RSP: 002b:00007f2464b88168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
> RAX: ffffffffffffffda RBX: 00007f2463fac050 RCX: 00007f2463e8c0c9
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000006
> RBP: 00007f2463ee7ae9 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000800100020013 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffd6bb8eb7f R14: 00007f2464b88300 R15: 0000000000022000
> </TASK>
>
> Showing all locks held in the system:
> 1 lock held by rcu_tasks_kthre/12:
> #0: ffffffff8c790f30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x26/0xc70 kernel/rcu/tasks.h:507
> 1 lock held by rcu_tasks_trace/13:
> #0: ffffffff8c790c30 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x26/0xc70 kernel/rcu/tasks.h:507
> 1 lock held by khungtaskd/27:
> #0: ffffffff8c791a80 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x57/0x264 kernel/locking/lockdep.c:6494
> 2 locks held by kworker/u4:3/46:
> 2 locks held by getty/4749:
> #0: ffff8880279ed098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x26/0x80 drivers/tty/tty_ldisc.c:244
> #1: ffffc900015802f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef4/0x13e0 drivers/tty/n_tty.c:2177
> 2 locks held by kworker/u4:9/5267:
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x86d/0x1710 kernel/workqueue.c:2260
> #1:
> ffffc90004e8fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1710 kernel/workqueue.c:2264
> 3 locks held by kworker/0:13/7504:
> #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
> #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
> #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
> #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
> #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
> #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x86d/0x1710 kernel/workqueue.c:2260
> #1: ffffc9000317fda8 ((work_completion)(&(&sw_ctx_tx->tx_work.work)->work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1710 kernel/workqueue.c:2264
> #2: ffff88803bd894d8 (&ctx->tx_lock){+.+.}-{3:3}, at: tx_work_handler+0x12b/0x190 net/tls/tls_sw.c:2419
> 2 locks held by kworker/u4:7/21254:
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
> #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x86d/0x1710 kernel/workqueue.c:2260
> #1: ffffc9000512fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1710 kernel/workqueue.c:2264
> 3 locks held by kworker/u4:14/22476:
> 1 lock held by syz-executor.5/30321:
> #0: ffff88803bd894d8 (&ctx->tx_lock){+.+.}-{3:3}, at: tls_sw_sendpage+0x83/0xe0 net/tls/tls_sw.c:1278
> 3 locks held by syz-executor.0/1632:
>
> =============================================
>
> NMI backtrace for cpu 0
> CPU: 0 PID: 27 Comm: khungtaskd Not tainted 6.2.0-rc3-syzkaller-00165-gd9fc1511728c #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
> nmi_cpu_backtrace.cold+0x24/0x18a lib/nmi_backtrace.c:111
> nmi_trigger_cpumask_backtrace+0x333/0x3c0 lib/nmi_backtrace.c:62
> trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
> check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
> watchdog+0xc75/0xfc0 kernel/hung_task.c:377
> kthread+0x2e8/0x3a0 kernel/kthread.c:376
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
> </TASK>
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1
> CPU: 1 PID: 1610 Comm: syz-executor.1 Not tainted 6.2.0-rc3-syzkaller-00165-gd9fc1511728c #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
> RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
> RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline]
> RIP: 0010:lock_is_held_type+0xee/0x140 kernel/locking/lockdep.c:5713
> Code: c0 45 31 ed 44 39 f0 41 0f 94 c5 48 c7 c7 e0 4e 4c 8a e8 35 15 00 00 b8 ff ff ff ff 65 0f c1 05 e0 60 fc 75 83 f8 01 75 29 9c <58> f6 c4 02 75 3d 48 f7 04 24 00 02 00 00 74 01 fb 48 83 c4 08 44
> RSP: 0018:ffffc9000320f508 EFLAGS: 00000046
> RAX: 0000000000000001 RBX: 0000000000000002 RCX: 0000000000000001
> RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
> RBP: ffffffff8c7919c0 R08: 0000000000000000 R09: ffffffff8e72f857
> R10: fffffbfff1ce5f0a R11: 0000000000000000 R12: ffff888025e09d40
> R13: 0000000000000000 R14: 00000000ffffffff R15: ffff888025e0a7a0
> FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f289dd821b8 CR3: 0000000032a9e000 CR4: 0000000000350ee0
> Call Trace:
> <TASK>
> lock_is_held include/linux/lockdep.h:283 [inline]
> rcu_read_lock_sched_held+0x3e/0x70 kernel/rcu/update.c:125
> trace_lock_acquire include/trace/events/lock.h:24 [inline]
> lock_acquire+0x500/0x630 kernel/locking/lockdep.c:5639
> rcu_lock_acquire include/linux/rcupdate.h:325 [inline]
> rcu_read_lock include/linux/rcupdate.h:764 [inline]
> folio_memcg_lock+0x3e/0x630 mm/memcontrol.c:2103
> page_remove_rmap+0x5f/0x1210 mm/rmap.c:1397
> zap_pte_range mm/memory.c:1405 [inline]
> zap_pmd_range mm/memory.c:1529 [inline]
> zap_pud_range mm/memory.c:1558 [inline]
> zap_p4d_range mm/memory.c:1579 [inline]
> unmap_page_range+0x234d/0x3c30 mm/memory.c:1600
> unmap_single_vma+0x190/0x2a0 mm/memory.c:1646
> unmap_vmas+0x226/0x370 mm/memory.c:1685
> exit_mmap+0x18d/0x7b0 mm/mmap.c:3085
> __mmput+0x128/0x4c0 kernel/fork.c:1207
> mmput+0x60/0x70 kernel/fork.c:1229
> exit_mm kernel/exit.c:563 [inline]
> do_exit+0x9ac/0x2950 kernel/exit.c:854
> do_group_exit+0xd4/0x2a0 kernel/exit.c:1012
> get_signal+0x21c3/0x2450 kernel/signal.c:2859
> arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
> exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
> exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203
> __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
> syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
> do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f249da8c0c9
> Code: Unable to access opcode bytes at 0x7f249da8c09f.
> RSP: 002b:00007f249e82b218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: 0000000000000001 RBX: 00007f249dbabf88 RCX: 00007f249da8c0c9
> RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f249dbabf8c
> RBP: 00007f249dbabf80 R08: 00007fffed1f8080 R09: 0000000000000000
> R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f249dbabf8c
> R13: 00007fffed11f2df R14: 00007f249e82b300 R15: 0000000000022000
> </TASK>
>
>
> ---
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>
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This looks suspicious to me

commit 79ffe6087e9145d2377385cac48d0d6a6b4225a5
Author: Jakub Kicinski <kuba@kernel.org>
Date: Tue Nov 5 14:24:35 2019 -0800

net/tls: add a TX lock

If tls_sw_sendpage() has to call sk_stream_wait_memory(),
sk_stream_wait_memory() is properly releasing the socket lock,
but knows nothing about mutex_{un}lock(&tls_ctx->tx_lock);