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* Unbreakable loop in fuse_fill_write_pages()
@ 2020-10-13 17:11 Qian Cai
  2020-10-13 18:40 ` Vivek Goyal
  0 siblings, 1 reply; 9+ messages in thread
From: Qian Cai @ 2020-10-13 17:11 UTC (permalink / raw)
  To: Miklos Szeredi, Vivek Goyal
  Cc: Alexander Viro, Stefan Hajnoczi, linux-fsdevel, linux-kernel, virtio-fs

Running some fuzzing on virtiofs with an unprivileged user on today's linux-next 
could trigger soft-lockups below.

# virtiofsd --socket-path=/tmp/vhostqemu -o source=$TESTDIR -o cache=always -o no_posix_lock

Basically, everything was blocking on inode_lock(inode) because one thread
(trinity-c33) was holding it but stuck in the loop in fuse_fill_write_pages()
and unable to exit for more than 10 minutes before I executed sysrq-t.
Afterwards, the systems was totally unresponsive:

kernel:NMI watchdog: Watchdog detected hard LOCKUP on cpu 8

To exit the loop, it needs,

iov_iter_advance(ii, tmp) to set "tmp" to non-zero for each iteration.

and

	} while (iov_iter_count(ii) && count < fc->max_write &&
		 ap->num_pages < max_pages && offset == 0);

== the thread is stuck in the loop ==
[10813.290694] task:trinity-c33     state:D stack:25888 pid:254219 ppid: 87180
flags:0x00004004
[10813.292671] Call Trace:
[10813.293379]  __schedule+0x71d/0x1b50
[10813.294182]  ? __sched_text_start+0x8/0x8
[10813.295146]  ? mark_held_locks+0xb0/0x110
[10813.296117]  schedule+0xbf/0x270
[10813.296782]  ? __lock_page_killable+0x276/0x830
[10813.297867]  io_schedule+0x17/0x60
[10813.298772]  __lock_page_killable+0x33b/0x830
[10813.299695]  ? wait_on_page_bit+0x710/0x710
[10813.300609]  ? __lock_page_or_retry+0x3c0/0x3c0
[10813.301894]  ? up_read+0x1a3/0x730
[10813.302791]  ? page_cache_free_page.isra.45+0x390/0x390
[10813.304077]  filemap_fault+0x2bd/0x2040
[10813.305019]  ? read_cache_page_gfp+0x10/0x10
[10813.306041]  ? lock_downgrade+0x700/0x700
[10813.306958]  ? replace_page_cache_page+0x1130/0x1130
[10813.308124]  __do_fault+0xf5/0x530
[10813.308968]  handle_mm_fault+0x1c0e/0x25b0
[10813.309955]  ? copy_page_range+0xfe0/0xfe0
[10813.310895]  do_user_addr_fault+0x383/0x820
[10813.312084]  exc_page_fault+0x56/0xb0
[10813.312979]  asm_exc_page_fault+0x1e/0x30
[10813.313978] RIP: 0010:iov_iter_fault_in_readable+0x271/0x350
fault_in_pages_readable at include/linux/pagemap.h:745
(inlined by) iov_iter_fault_in_readable at lib/iov_iter.c:438
[10813.315293] Code: 48 39 d7 0f 82 1a ff ff ff 0f 01 cb 0f ae e8 44 89 c0 8a 0a
0f 01 ca 88 4c 24 70 85 c0 74 da e9 f8 fe ff ff 0f 01 cb 0f ae e8 <8a> 11 0f 01
ca 88 54 24 30 85 c0 0f 85 04 ff ff ff 48 29 ee e9
 45
[10813.319196] RSP: 0018:ffffc90017ccf830 EFLAGS: 00050246
[10813.320446] RAX: 0000000000000000 RBX: 1ffff92002f99f08 RCX: 00007fe284f1004c
[10813.322202] RDX: 0000000000000001 RSI: 0000000000001000 RDI: ffff8887a7664000
[10813.323729] RBP: 0000000000001000 R08: 0000000000000000 R09: 0000000000000000
[10813.325282] R10: ffffc90017ccfd48 R11: ffffed102789d5ff R12: ffff8887a7664020
[10813.326898] R13: ffffc90017ccfd40 R14: dffffc0000000000 R15: 0000000000e0df6a
[10813.328456]  ? iov_iter_revert+0x8e0/0x8e0
[10813.329404]  ? copyin+0x96/0xc0
[10813.330230]  ? iov_iter_copy_from_user_atomic+0x1f0/0xa40
[10813.331742]  fuse_perform_write+0x3eb/0xf20 [fuse]
fuse_fill_write_pages at fs/fuse/file.c:1150
(inlined by) fuse_perform_write at fs/fuse/file.c:1226
[10813.332880]  ? fuse_file_fallocate+0x5f0/0x5f0 [fuse]
[10813.334090]  fuse_file_write_iter+0x6b7/0x900 [fuse]
[10813.335191]  do_iter_readv_writev+0x42b/0x6d0
[10813.336161]  ? new_sync_write+0x610/0x610
[10813.337194]  do_iter_write+0x11f/0x5b0
[10813.338177]  ? __sb_start_write+0x229/0x2d0
[10813.339169]  vfs_writev+0x16d/0x2d0
[10813.339973]  ? vfs_iter_write+0xb0/0xb0
[10813.340950]  ? __fdget_pos+0x9c/0xb0
[10813.342039]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10813.343120]  ? rcu_read_lock_bh_held+0xb0/0xb0
[10813.344104]  ? find_held_lock+0x33/0x1c0
[10813.345050]  do_writev+0xfb/0x1e0
[10813.345920]  ? vfs_writev+0x2d0/0x2d0
[10813.346802]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
[10813.348026]  ? syscall_enter_from_user_mode+0x1c/0x50
[10813.349197]  do_syscall_64+0x33/0x40
[10813.350026]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

== soft-lockups ==
[10579.953730][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10579.955016][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10579.956467][  T348] task:trinity-c25     state:D stack:26704 pid:253906 ppid: 87180 flags:0x00004002
[10579.958028][  T348] Call Trace:
[10579.958609][  T348]  __schedule+0x71d/0x1b50
[10579.959309][  T348]  ? __sched_text_start+0x8/0x8
[10579.960144][  T348]  schedule+0xbf/0x270
[10579.960774][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10579.961828][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10579.962675][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10579.963721][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10579.964658][  T348]  ? lock_acquire+0x1c8/0x820
[10579.965453][  T348]  ? down_write+0x138/0x150
[10579.966237][  T348]  ? down_write+0xb3/0x150
[10579.966994][  T348]  down_write+0x138/0x150
[10579.967787][  T348]  ? down_write_killable_nested+0x170/0x170
[10579.968844][  T348]  fuse_flush+0x1a0/0x500 [fuse]
[10579.969732][  T348]  ? fuse_file_lock+0x190/0x190 [fuse]
[10579.970741][  T348]  filp_close+0x97/0x110
[10579.971560][  T348]  put_files_struct+0x15a/0x250
[10579.972393][  T348]  do_exit+0x8a9/0x23a0
[10579.973107][  T348]  ? mm_update_next_owner+0x740/0x740
[10579.974048][  T348]  ? up_read+0x1a3/0x730
[10579.974712][  T348]  ? down_read_nested+0x420/0x420
[10579.975589][  T348]  ? syscall_enter_from_user_mode+0x17/0x50
[10579.976686][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10579.977625][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10579.978522][  T348]  do_group_exit+0xeb/0x2d0
[10579.979329][  T348]  __x64_sys_exit_group+0x35/0x40
[10579.980173][  T348]  do_syscall_64+0x33/0x40
[10579.980898][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10579.981979][  T348] RIP: 0033:0x7fe287a39256
[10579.982726][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a3922c.
[10579.983989][  T348] RSP: 002b:00007ffc5fb89ee8 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7
[10579.985426][  T348] RAX: ffffffffffffffda RBX: 00007fe288002000 RCX: 00007fe287a39256
[10579.986747][  T348] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[10579.988090][  T348] RBP: 0000000000001000 R08: 00000000000000e7 R09: ffffffffffffff80
[10579.989422][  T348] R10: 0000000000000005 R11: 0000000000000206 R12: 00007fe288002001
[10579.990762][  T348] R13: 00007fe288002fe9 R14: 000000000000003a R15: 0000000055555556
[10579.992179][  T348] INFO: task trinity-c38:253929 blocked for more than 122 seconds.
[10579.993503][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10579.994787][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10579.996298][  T348] task:trinity-c38     state:D stack:26896 pid:253929 ppid: 87180 flags:0x00000004
[10579.997897][  T348] Call Trace:
[10579.998475][  T348]  __schedule+0x71d/0x1b50
[10579.999216][  T348]  ? __sched_text_start+0x8/0x8
[10580.000107][  T348]  schedule+0xbf/0x270
[10580.000823][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10580.001794][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10580.002676][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.003684][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.004650][  T348]  ? lock_acquire+0x1c8/0x820
[10580.005405][  T348]  ? chmod_common+0x148/0x390
[10580.006219][  T348]  ? lock_acquire+0x1c8/0x820
[10580.007035][  T348]  ? rcu_read_unlock+0x40/0x40
[10580.007765][  T348]  ? down_write+0x138/0x150
[10580.008562][  T348]  down_write+0x138/0x150
[10580.009244][  T348]  ? down_write_killable_nested+0x170/0x170
[10580.010254][  T348]  ? __sb_start_write+0x229/0x2d0
[10580.011140][  T348]  chmod_common+0x148/0x390
[10580.011949][  T348]  ? __x64_sys_chroot+0x1e0/0x1e0
[10580.012740][  T348]  ? lock_downgrade+0x700/0x700
[10580.013567][  T348]  ? syscall_enter_from_user_mode+0x17/0x50
[10580.014569][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.015460][  T348]  __x64_sys_fchmod+0x6c/0xa0
[10580.016249][  T348]  do_syscall_64+0x33/0x40
[10580.017004][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.017995][  T348] RIP: 0033:0x7fe287a6778d
[10580.018796][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a67763.
[10580.020098][  T348] RSP: 002b:00007ffc5fb8abe8 EFLAGS: 00000246 ORIG_RAX: 000000000000005b
[10580.021572][  T348] RAX: ffffffffffffffda RBX: 000000000000005b RCX: 00007fe287a6778d
[10580.022902][  T348] RDX: fffffffffffffffb RSI: 0000000000000084 RDI: 00000000000001a0
[10580.024246][  T348] RBP: 000000000000005b R08: 00000000bcbcbcbc R09: 00000000000000d8
[10580.025580][  T348] R10: 00bfa42b104256ef R11: 0000000000000246 R12: 0000000000000002
[10580.026934][  T348] R13: 00007fe288043058 R14: 00007fe2881546c0 R15: 00007fe288043000
[10580.028237][  T348] INFO: task trinity-c2:254053 blocked for more than 122 seconds.
[10580.029594][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.030838][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.032359][  T348] task:trinity-c2      state:D stack:26704 pid:254053 ppid: 87180 flags:0x00004002
[10580.033911][  T348] Call Trace:
[10580.034442][  T348]  __schedule+0x71d/0x1b50
[10580.035243][  T348]  ? __sched_text_start+0x8/0x8
[10580.036011][  T348]  schedule+0xbf/0x270
[10580.036750][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10580.037721][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10580.038554][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.039528][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.040460][  T348]  ? lock_acquire+0x1c8/0x820
[10580.041325][  T348]  ? down_write+0x138/0x150
[10580.042058][  T348]  ? down_write+0xb3/0x150
[10580.042833][  T348]  down_write+0x138/0x150
[10580.043535][  T348]  ? down_write_killable_nested+0x170/0x170
[10580.044569][  T348]  fuse_flush+0x1a0/0x500 [fuse]
[10580.045408][  T348]  ? fuse_file_lock+0x190/0x190 [fuse]
[10580.046338][  T348]  filp_close+0x97/0x110
[10580.047069][  T348]  put_files_struct+0x15a/0x250
[10580.047884][  T348]  do_exit+0x8a9/0x23a0
[10580.048652][  T348]  ? mm_update_next_owner+0x740/0x740
[10580.049585][  T348]  ? up_read+0x1a3/0x730
[10580.050306][  T348]  ? down_read_nested+0x420/0x420
[10580.051309][  T348]  ? syscall_enter_from_user_mode+0x17/0x50
[10580.052326][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.053330][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.054269][  T348]  do_group_exit+0xeb/0x2d0
[10580.054996][  T348]  __x64_sys_exit_group+0x35/0x40
[10580.055871][  T348]  do_syscall_64+0x33/0x40
[10580.056661][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.057602][  T348] RIP: 0033:0x7fe287a39256
[10580.058376][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a3922c.
[10580.059638][  T348] RSP: 002b:00007ffc5fb89f28 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7
[10580.061034][  T348] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fe287a39256
[10580.062400][  T348] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[10580.063772][  T348] RBP: 0000000000001000 R08: 00000000000000e7 R09: ffffffffffffff80
[10580.065155][  T348] R10: 0000000000000005 R11: 0000000000000206 R12: 00007fe28813f058
[10580.066553][  T348] R13: 00007fe28813f058 R14: 0000000000000001 R15: 0000000000000030
[10580.067903][  T348] INFO: task trinity-c18:254111 blocked for more than 122 seconds.
[10580.069228][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.070412][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.071999][  T348] task:trinity-c18     state:D stack:26704 pid:254111 ppid: 87180 flags:0x00004002
[10580.073522][  T348] Call Trace:
[10580.074081][  T348]  __schedule+0x71d/0x1b50
[10580.074837][  T348]  ? __sched_text_start+0x8/0x8
[10580.075639][  T348]  schedule+0xbf/0x270
[10580.076359][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10580.077348][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10580.078158][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.079179][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.080200][  T348]  ? lock_acquire+0x1c8/0x820
[10580.080946][  T348]  ? down_write+0x138/0x150
[10580.081715][  T348]  ? down_write+0xb3/0x150
[10580.082530][  T348]  down_write+0x138/0x150
[10580.083205][  T348]  ? down_write_killable_nested+0x170/0x170
[10580.084211][  T348]  fuse_flush+0x1a0/0x500 [fuse]
[10580.085075][  T348]  ? fuse_file_lock+0x190/0x190 [fuse]
[10580.085977][  T348]  filp_close+0x97/0x110
[10580.086671][  T348]  put_files_struct+0x15a/0x250
[10580.087576][  T348]  do_exit+0x8a9/0x23a0
[10580.088207][  T348]  ? _raw_spin_unlock+0x1/0x30
[10580.089073][  T348]  ? _raw_spin_unlock_irq+0x1f/0x30
[10580.090009][  T348]  ? signal_setup_done+0x1a3/0x230
[10580.090875][  T348]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
[10580.091871][  T348]  ? mm_update_next_owner+0x740/0x740
[10580.092796][  T348]  ? fpu__clear+0xd5/0x240
[10580.093593][  T348]  ? __local_bh_enable_ip+0xa0/0xf0
[10580.094518][  T348]  ? fpu__clear+0xeb/0x240
[10580.095331][  T348]  ? syscall_enter_from_user_mode+0x17/0x50
[10580.096347][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.097322][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.098190][  T348]  do_group_exit+0xeb/0x2d0
[10580.099028][  T348]  __x64_sys_exit_group+0x35/0x40
[10580.099905][  T348]  do_syscall_64+0x33/0x40
[10580.100637][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.101694][  T348] RIP: 0033:0x7fe287a39256
[10580.102472][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a3922c.
[10580.103736][  T348] RSP: 002b:00007ffc5fb89ce8 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7
[10580.105231][  T348] RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 00007fe287a39256
[10580.106578][  T348] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[10580.107917][  T348] RBP: 0000000000000000 R08: 00000000000000e7 R09: ffffffffffffff80
[10580.109213][  T348] R10: 0000000000000005 R11: 0000000000000206 R12: 00007ffc5fb8aa00
[10580.110526][  T348] R13: 0000000000423e96 R14: 00007ffc5fb8ab40 R15: 0000000000000001
[10580.111923][  T348] INFO: task trinity-c14:254134 blocked for more than 123 seconds.
[10580.113207][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.114465][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.115942][  T348] task:trinity-c14     state:D stack:26448 pid:254134 ppid: 87180 flags:0x00000004
[10580.117496][  T348] Call Trace:
[10580.118065][  T348]  __schedule+0x71d/0x1b50
[10580.118804][  T348]  ? __sched_text_start+0x8/0x8
[10580.119711][  T348]  schedule+0xbf/0x270
[10580.120378][  T348]  schedule_preempt_disabled+0xc/0x20
[10580.121307][  T348]  __mutex_lock+0x9f1/0x1360
[10580.122117][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.122828][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
[10580.123780][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.124696][  T348]  ? rcu_read_lock_bh_held+0xb0/0xb0
[10580.125522][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.126289][  T348]  __fdget_pos+0x9c/0xb0
[10580.126981][  T348]  do_writev+0x6d/0x1e0
[10580.127650][  T348]  ? vfs_writev+0x2d0/0x2d0
[10580.128394][  T348]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
[10580.129423][  T348]  ? syscall_enter_from_user_mode+0x1c/0x50
[10580.130416][  T348]  do_syscall_64+0x33/0x40
[10580.131233][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.132250][  T348] RIP: 0033:0x7fe287a6778d
[10580.133013][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a67763.
[10580.134223][  T348] RSP: 002b:00007ffc5fb8abe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
[10580.135718][  T348] RAX: ffffffffffffffda RBX: 0000000000000014 RCX: 00007fe287a6778d
[10580.137065][  T348] RDX: 0000000000000049 RSI: 000000000267d300 RDI: 00000000000001a0
[10580.138443][  T348] RBP: 0000000000000014 R08: 00000000efefefef R09: 000000005e5e5e5e
[10580.139820][  T348] R10: 0041a7001010e807 R11: 0000000000000246 R12: 0000000000000002
[10580.141190][  T348] R13: 00007fe2880eb058 R14: 00007fe2881546c0 R15: 00007fe2880eb000
[10580.142571][  T348] INFO: task trinity-c36:254165 blocked for more than 123 seconds.
[10580.143924][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.145158][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.146636][  T348] task:trinity-c36     state:D stack:26704 pid:254165 ppid: 87180 flags:0x00000004
[10580.148260][  T348] Call Trace:
[10580.148789][  T348]  __schedule+0x71d/0x1b50
[10580.149532][  T348]  ? __sched_text_start+0x8/0x8
[10580.150343][  T348]  schedule+0xbf/0x270
[10580.151044][  T348]  schedule_preempt_disabled+0xc/0x20
[10580.152006][  T348]  __mutex_lock+0x9f1/0x1360
[10580.152777][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.153484][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
[10580.154432][  T348]  ? find_held_lock+0x33/0x1c0
[10580.155220][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.155934][  T348]  __fdget_pos+0x9c/0xb0
[10580.156660][  T348]  __x64_sys_getdents+0xff/0x230
[10580.157488][  T348]  ? __x64_sys_old_readdir+0x170/0x170
[10580.158429][  T348]  ? iterate_dir+0x610/0x610
[10580.159176][  T348]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
[10580.160214][  T348]  ? syscall_enter_from_user_mode+0x1c/0x50
[10580.161253][  T348]  do_syscall_64+0x33/0x40
[10580.162005][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.162964][  T348] RIP: 0033:0x7fe287a6778d
[10580.163713][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a67763.
[10580.164940][  T348] RSP: 002b:00007ffc5fb8abe8 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
[10580.166354][  T348] RAX: ffffffffffffffda RBX: 000000000000004e RCX: 00007fe287a6778d
[10580.167703][  T348] RDX: 0000000000000004 RSI: 00007fe285f4c000 RDI: 00000000000001a0
[10580.169039][  T348] RBP: 000000000000004e R08: fffffffffffffff9 R09: fffffffffffffff6
[10580.170347][  T348] R10: 149a823509203c58 R11: 0000000000000246 R12: 0000000000000002
[10580.171835][  T348] R13: 00007fe288051058 R14: 00007fe2881546c0 R15: 00007fe288051000
[10580.173198][  T348] INFO: task trinity-c10:254420 blocked for more than 123 seconds.
[10580.174601][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.175869][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.177311][  T348] task:trinity-c10     state:D stack:26896 pid:254420 ppid: 87180 flags:0x00000004
[10580.178940][  T348] Call Trace:
[10580.179573][  T348]  __schedule+0x71d/0x1b50
[10580.180306][  T348]  ? __sched_text_start+0x8/0x8
[10580.181142][  T348]  schedule+0xbf/0x270
[10580.181874][  T348]  schedule_preempt_disabled+0xc/0x20
[10580.182748][  T348]  __mutex_lock+0x9f1/0x1360
[10580.183502][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.184251][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
[10580.185163][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.186072][  T348]  ? rcu_read_lock_bh_held+0xb0/0xb0
[10580.187012][  T348]  ? __task_pid_nr_ns+0x127/0x3a0
[10580.187871][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.188578][  T348]  __fdget_pos+0x9c/0xb0
[10580.189326][  T348]  ksys_read+0x66/0x1c0
[10580.189998][  T348]  ? vfs_write+0x5b0/0x5b0
[10580.190818][  T348]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
[10580.191920][  T348]  ? syscall_enter_from_user_mode+0x1c/0x50
[10580.192936][  T348]  do_syscall_64+0x33/0x40
[10580.193615][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.194632][  T348] RIP: 0033:0x7fe287a6778d
[10580.195401][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a67763.
[10580.196638][  T348] RSP: 002b:00007ffc5fb8abe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[10580.198043][  T348] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe287a6778d
[10580.199400][  T348] RDX: 0000000000001000 RSI: 00007fe285b4c000 RDI: 00000000000001a0
[10580.200781][  T348] RBP: 0000000000000000 R08: 00aa60de2c3afd2c R09: 000000000000e000
[10580.202209][  T348] R10: ffffffffffffffdb R11: 0000000000000246 R12: 0000000000000002
[10580.203567][  T348] R13: 00007fe288107058 R14: 00007fe2881546c0 R15: 00007fe288107000
[10580.204886][  T348] INFO: task trinity-c42:254437 blocked for more than 123 seconds.
[10580.206177][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.207398][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.208828][  T348] task:trinity-c42     state:D stack:27088 pid:254437 ppid: 87180 flags:0x00000004
[10580.210393][  T348] Call Trace:
[10580.210891][  T348]  __schedule+0x71d/0x1b50
[10580.211768][  T348]  ? __sched_text_start+0x8/0x8
[10580.212537][  T348]  schedule+0xbf/0x270
[10580.213236][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10580.214213][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10580.215010][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.215990][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.216942][  T348]  ? lock_acquire+0x1c8/0x820
[10580.217787][  T348]  ? mark_lock.part.47+0x109/0x1910
[10580.218584][  T348]  ? down_write+0x138/0x150
[10580.219335][  T348]  ? down_write+0xb3/0x150
[10580.220101][  T348]  down_write+0x138/0x150
[10580.220792][  T348]  ? down_write_killable_nested+0x170/0x170
[10580.221843][  T348]  fuse_file_write_iter+0x22e/0x900 [fuse]
[10580.222859][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.223904][  T348]  new_sync_write+0x3aa/0x610
[10580.224631][  T348]  ? new_sync_read+0x600/0x600
[10580.225427][  T348]  ? vfs_write+0x36c/0x5b0
[10580.226166][  T348]  ? rcu_read_lock_any_held+0xcd/0xf0
[10580.227018][  T348]  vfs_write+0x3e9/0x5b0
[10580.227804][  T348]  ksys_pwrite64+0x116/0x140
[10580.228621][  T348]  ? __x64_sys_pread64+0xf0/0xf0
[10580.229375][  T348]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
[10580.230364][  T348]  ? syscall_enter_from_user_mode+0x1c/0x50
[10580.231427][  T348]  do_syscall_64+0x33/0x40
[10580.232203][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.233152][  T348] RIP: 0033:0x7fe287a6778d
[10580.233913][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a67763.
[10580.235172][  T348] RSP: 002b:00007ffc5fb8abe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
[10580.236639][  T348] RAX: ffffffffffffffda RBX: 0000000000000012 RCX: 00007fe287a6778d
[10580.237930][  T348] RDX: 0000000000000986 RSI: 000000000266e960 RDI: 00000000000001a0
[10580.239174][  T348] RBP: 0000000000000012 R08: 00000000232714aa R09: 0000000000000077
[10580.240466][  T348] R10: 4200490003c05550 R11: 0000000000000246 R12: 0000000000000002
[10580.241848][  T348] R13: 00007fe288027058 R14: 00007fe2881546c0 R15: 00007fe288027000
[10580.243194][  T348] INFO: task trinity-subchil:254451 blocked for more than 123 seconds.
[10580.244565][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.245760][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.247194][  T348] task:trinity-subchil state:D stack:27664 pid:254451 ppid:254226 flags:0x00004000
[10580.248682][  T348] Call Trace:
[10580.249157][  T348]  __schedule+0x71d/0x1b50
[10580.249926][  T348]  ? __sched_text_start+0x8/0x8
[10580.250653][  T348]  schedule+0xbf/0x270
[10580.251479][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10580.252378][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10580.253114][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.254133][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.255099][  T348]  ? lock_acquire+0x1c8/0x820
[10580.255813][  T348]  ? down_write+0x138/0x150
[10580.256597][  T348]  ? down_write+0xb3/0x150
[10580.257350][  T348]  down_write+0x138/0x150
[10580.258012][  T348]  ? down_write_killable_nested+0x170/0x170
[10580.259034][  T348]  fuse_flush+0x1a0/0x500 [fuse]
[10580.259927][  T348]  ? fuse_file_lock+0x190/0x190 [fuse]
[10580.260774][  T348]  filp_close+0x97/0x110
[10580.261521][  T348]  put_files_struct+0x15a/0x250
[10580.262402][  T348]  do_exit+0x8a9/0x23a0
[10580.263052][  T348]  ? mm_update_next_owner+0x740/0x740
[10580.263949][  T348]  ? up_read+0x1a3/0x730
[10580.264699][  T348]  ? down_read_nested+0x420/0x420
[10580.265463][  T348]  ? syscall_enter_from_user_mode+0x17/0x50
[10580.266417][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.267335][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.268302][  T348]  do_group_exit+0xeb/0x2d0
[10580.268978][  T348]  __x64_sys_exit_group+0x35/0x40
[10580.269801][  T348]  do_syscall_64+0x33/0x40
[10580.270565][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.271568][  T348] RIP: 0033:0x7fe287a39256
[10580.272331][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a3922c.
[10580.273576][  T348] RSP: 002b:00007ffc5fb8ac68 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
[10580.275038][  T348] RAX: ffffffffffffffda RBX: 00007fe2880b3000 RCX: 00007fe287a39256
[10580.276310][  T348] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[10580.277673][  T348] RBP: 0000000000000000 R08: 00000000000000e7 R09: ffffffffffffff80
[10580.279016][  T348] R10: 0000000000000005 R11: 0000000000000202 R12: 00007fe2880b3000
[10580.280344][  T348] R13: 00007fe2880b3058 R14: 0000000000000000 R15: 0000000000000030
[10580.281779][  T348] INFO: task trinity-subchil:254452 blocked for more than 123 seconds.
[10580.283124][  T348]       Tainted: G           O      5.9.0-next-20201013+ #2
[10580.284289][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[10580.285737][  T348] task:trinity-subchil state:D stack:27664 pid:254452 ppid:254342 flags:0x00004000
[10580.287279][  T348] Call Trace:
[10580.287752][  T348]  __schedule+0x71d/0x1b50
[10580.288578][  T348]  ? __sched_text_start+0x8/0x8
[10580.289384][  T348]  schedule+0xbf/0x270
[10580.289993][  T348]  rwsem_down_write_slowpath+0x8ea/0xf30
[10580.290973][  T348]  ? rwsem_mark_wake+0x8d0/0x8d0
[10580.291919][  T348]  ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
[10580.292913][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.293864][  T348]  ? lock_acquire+0x1c8/0x820
[10580.294685][  T348]  ? down_write+0x138/0x150
[10580.295407][  T348]  ? down_write+0xb3/0x150
[10580.296178][  T348]  down_write+0x138/0x150
[10580.296964][  T348]  ? down_write_killable_nested+0x170/0x170
[10580.297959][  T348]  fuse_flush+0x1a0/0x500 [fuse]
[10580.298792][  T348]  ? fuse_file_lock+0x190/0x190 [fuse]
[10580.299719][  T348]  filp_close+0x97/0x110
[10580.300390][  T348]  put_files_struct+0x15a/0x250
[10580.301290][  T348]  do_exit+0x8a9/0x23a0
[10580.301918][  T348]  ? mm_update_next_owner+0x740/0x740
[10580.302843][  T348]  ? up_read+0x1a3/0x730
[10580.303605][  T348]  ? down_read_nested+0x420/0x420
[10580.304378][  T348]  ? syscall_enter_from_user_mode+0x17/0x50
[10580.305392][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.306346][  T348]  ? rcu_read_lock_sched_held+0x9c/0xd0
[10580.307267][  T348]  do_group_exit+0xeb/0x2d0
[10580.307925][  T348]  __x64_sys_exit_group+0x35/0x40
[10580.308785][  T348]  do_syscall_64+0x33/0x40
[10580.309512][  T348]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10580.310465][  T348] RIP: 0033:0x7fe287a39256
[10580.311280][  T348] Code: Unable to access opcode bytes at RIP 0x7fe287a3922c.
[10580.312520][  T348] RSP: 002b:00007ffc5fb8ac68 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
[10580.313932][  T348] RAX: ffffffffffffffda RBX: 00007fe2880c1000 RCX: 00007fe287a39256
[10580.315276][  T348] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[10580.316697][  T348] RBP: 0000000000000000 R08: 00000000000000e7 R09: ffffffffffffff80
[10580.318096][  T348] R10: 0000000000000005 R11: 0000000000000202 R12: 00007fe2880c1000
[10580.319423][  T348] R13: 00007fe2880c1058 R14: 0000000000000000 R15: 0000000000000030
[10580.320790][  T348] 
[10580.320790][  T348] Showing all locks held in the system:
[10580.322269][  T348] 1 lock held by khungtaskd/348:
[10580.323092][  T348]  #0: ffffffff984ceee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire.constprop.52+0x0/0x30
[10580.324875][  T348] 2 locks held by systemd-journal/787:
[10580.325886][  T348] 5 locks held by in:imjournal/54792:
[10580.326834][  T348] 2 locks held by trinity-c11/253653:
[10580.327686][  T348]  #0: ffff888bccaf2098 (&rq->lock){-.-.}-{2:2}, at: newidle_balance+0x9c9/0xec0
[10580.329282][  T348]  #1: ffffffff984ceee0 (rcu_read_lock){....}-{1:2}, at: perf_iterate_sb+0x0/0x510
[10580.330893][  T348] 1 lock held by trinity-c25/253906:
[10580.331886][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.333762][  T348] 2 locks held by trinity-c38/253929:
[10580.334690][  T348]  #0: ffff888133e59430 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x37/0xa0
[10580.336191][  T348]  #1: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: chmod_common+0x148/0x390
[10580.338056][  T348] 2 locks held by trinity-c3/254046:
[10580.338886][  T348]  #0: ffff888bcd1b2098 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x208/0x1b50
[10580.340366][  T348]  #1: ffff88814c96d620 (&ctx->lock){-.-.}-{2:2}, at: __perf_event_task_sched_out+0x41e/0x1450
[10580.342178][  T348] 1 lock held by trinity-c2/254053:
[10580.343074][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.344792][  T348] 1 lock held by trinity-c18/254111:
[10580.345695][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.347647][  T348] 1 lock held by trinity-c14/254134:
[10580.348480][  T348]  #0: ffff888765a3c730 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x9c/0xb0
[10580.350051][  T348] 1 lock held by trinity-c36/254165:
[10580.350867][  T348]  #0: ffff888765a3c730 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x9c/0xb0
[10580.352486][  T348] 3 locks held by trinity-c33/254219:
[10580.353342][  T348]  #0: ffff888765a3c730 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x9c/0xb0
[10580.354938][  T348]  #1: ffff888133e59430 (sb_writers#16){.+.+}-{0:0}, at: vfs_writev+0x20d/0x2d0
[10580.356485][  T348]  #2: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_file_write_iter+0x22e/0x900 [fuse]
[10580.358569][  T348] 2 locks held by trinity-c17/254306:
[10580.359425][  T348]  #0: ffff888bcca72098 (&rq->lock){-.-.}-{2:2}, at: newidle_balance+0x9c9/0xec0
[10580.361024][  T348]  #1: ffff888926d8b820 (&ctx->lock){-.-.}-{2:2}, at: __perf_event_task_sched_out+0x41e/0x1450
[10580.362834][  T348] 2 locks held by trinity-c34/254348:
[10580.363761][  T348]  #0: ffff888bccc32098 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x208/0x1b50
[10580.365306][  T348]  #1: ffffffff984e2f08 (tk_core.seq.seqcount){----}-{0:0}, at: __perf_event_task_sched_out+0x41e/0x1450
[10580.367250][  T348] 1 lock held by trinity-c10/254420:
[10580.368134][  T348]  #0: ffff888765a3c730 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x9c/0xb0
[10580.369683][  T348] 2 locks held by trinity-c42/254437:
[10580.370590][  T348]  #0: ffff888133e59430 (sb_writers#16){.+.+}-{0:0}, at: vfs_write+0x36c/0x5b0
[10580.372159][  T348]  #1: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_file_write_iter+0x22e/0x900 [fuse]
[10580.374134][  T348] 1 lock held by trinity-subchil/254451:
[10580.375141][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.376963][  T348] 1 lock held by trinity-subchil/254452:
[10580.377925][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.379894][  T348] 1 lock held by trinity-c28/254453:
[10580.380783][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.382701][  T348] 1 lock held by trinity-subchil/254454:
[10580.383660][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.385554][  T348] 1 lock held by trinity-subchil/254455:
[10580.386562][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.388314][  T348] 1 lock held by trinity-c27/254456:
[10580.389224][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.391160][  T348] 1 lock held by trinity-subchil/254457:
[10580.392087][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.393979][  T348] 1 lock held by trinity-subchil/254460:
[10580.394948][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.396757][  T348] 1 lock held by trinity-c9/254461:
[10580.397644][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.399508][  T348] 1 lock held by trinity-subchil/254462:
[10580.400442][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.402424][  T348] 1 lock held by trinity-c24/254464:
[10580.403378][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.405237][  T348] 1 lock held by trinity-c46/254466:
[10580.406179][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.408058][  T348] 1 lock held by trinity-subchil/254468:
[10580.409026][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.410934][  T348] 1 lock held by trinity-c34/254469:
[10580.411903][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.413665][  T348] 1 lock held by trinity-subchil/254470:
[10580.414648][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.416421][  T348] 1 lock held by trinity-subchil/254471:
[10580.417365][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.419298][  T348] 1 lock held by trinity-subchil/254472:
[10580.420149][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.422064][  T348] 1 lock held by trinity-c30/254474:
[10580.422953][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.424714][  T348] 1 lock held by trinity-subchil/254475:
[10580.425695][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.427465][  T348] 1 lock held by trinity-c31/254476:
[10580.428366][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.430304][  T348] 1 lock held by trinity-c11/254477:
[10580.431160][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.433073][  T348] 1 lock held by trinity-c0/254478:
[10580.433979][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.435779][  T348] 1 lock held by trinity-subchil/254481:
[10580.436739][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.438628][  T348] 1 lock held by trinity-c29/254482:
[10580.439521][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.441414][  T348] 1 lock held by trinity-c8/254484:
[10580.442344][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.444198][  T348] 1 lock held by trinity-c5/254485:
[10580.445123][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.447055][  T348] 1 lock held by trinity-c15/254486:
[10580.447923][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.449816][  T348] 1 lock held by trinity-subchil/254487:
[10580.450749][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.452639][  T348] 1 lock held by trinity-c4/254488:
[10580.453494][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.455363][  T348] 1 lock held by trinity-subchil/254489:
[10580.456303][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.458074][  T348] 1 lock held by trinity-c3/254490:
[10580.458975][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.460773][  T348] 1 lock held by trinity-c21/254493:
[10580.461776][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.463657][  T348] 1 lock held by trinity-subchil/254495:
[10580.464497][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.466363][  T348] 1 lock held by trinity-subchil/254496:
[10580.467312][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.469139][  T348] 1 lock held by trinity-subchil/254497:
[10580.470096][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.471975][  T348] 1 lock held by trinity-c32/254498:
[10580.472774][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.474634][  T348] 1 lock held by trinity-c43/254499:
[10580.475441][  T348]  #0: ffff8886e59d2088 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: fuse_flush+0x1a0/0x500 [fuse]
[10580.477308][  T348] 
[10580.477652][  T348] =============================================
[10580.477652][  T348


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 17:11 Unbreakable loop in fuse_fill_write_pages() Qian Cai
@ 2020-10-13 18:40 ` Vivek Goyal
  2020-10-13 18:58   ` Vivek Goyal
  2020-10-15 13:18   ` Qian Cai
  0 siblings, 2 replies; 9+ messages in thread
From: Vivek Goyal @ 2020-10-13 18:40 UTC (permalink / raw)
  To: Qian Cai
  Cc: Miklos Szeredi, Alexander Viro, Stefan Hajnoczi, linux-fsdevel,
	linux-kernel, virtio-fs

On Tue, Oct 13, 2020 at 01:11:05PM -0400, Qian Cai wrote:
> Running some fuzzing on virtiofs with an unprivileged user on today's linux-next 
> could trigger soft-lockups below.
> 
> # virtiofsd --socket-path=/tmp/vhostqemu -o source=$TESTDIR -o cache=always -o no_posix_lock
> 
> Basically, everything was blocking on inode_lock(inode) because one thread
> (trinity-c33) was holding it but stuck in the loop in fuse_fill_write_pages()
> and unable to exit for more than 10 minutes before I executed sysrq-t.
> Afterwards, the systems was totally unresponsive:
> 
> kernel:NMI watchdog: Watchdog detected hard LOCKUP on cpu 8
> 
> To exit the loop, it needs,
> 
> iov_iter_advance(ii, tmp) to set "tmp" to non-zero for each iteration.
> 
> and
> 
> 	} while (iov_iter_count(ii) && count < fc->max_write &&
> 		 ap->num_pages < max_pages && offset == 0);
> 
> == the thread is stuck in the loop ==
> [10813.290694] task:trinity-c33     state:D stack:25888 pid:254219 ppid: 87180
> flags:0x00004004
> [10813.292671] Call Trace:
> [10813.293379]  __schedule+0x71d/0x1b50
> [10813.294182]  ? __sched_text_start+0x8/0x8
> [10813.295146]  ? mark_held_locks+0xb0/0x110
> [10813.296117]  schedule+0xbf/0x270
> [10813.296782]  ? __lock_page_killable+0x276/0x830
> [10813.297867]  io_schedule+0x17/0x60
> [10813.298772]  __lock_page_killable+0x33b/0x830

This seems to suggest that filemap_fault() is blocked on page lock and
is sleeping. For some reason it never wakes up. Not sure why.

And this will be called from.

fuse_fill_write_pages()
   iov_iter_fault_in_readable()

So fuse code will take inode_lock() and then looks like same process
is sleeping waiting on page lock. And rest of the processes get blocked
behind inode lock.

If we are woken up (while waiting on page lock), we should make forward
progress. Question is what page it is and why the entity which is
holding lock is not releasing lock.

Thanks
Vivek

> [10813.299695]  ? wait_on_page_bit+0x710/0x710
> [10813.300609]  ? __lock_page_or_retry+0x3c0/0x3c0
> [10813.301894]  ? up_read+0x1a3/0x730
> [10813.302791]  ? page_cache_free_page.isra.45+0x390/0x390
> [10813.304077]  filemap_fault+0x2bd/0x2040
> [10813.305019]  ? read_cache_page_gfp+0x10/0x10
> [10813.306041]  ? lock_downgrade+0x700/0x700
> [10813.306958]  ? replace_page_cache_page+0x1130/0x1130
> [10813.308124]  __do_fault+0xf5/0x530
> [10813.308968]  handle_mm_fault+0x1c0e/0x25b0
> [10813.309955]  ? copy_page_range+0xfe0/0xfe0
> [10813.310895]  do_user_addr_fault+0x383/0x820
> [10813.312084]  exc_page_fault+0x56/0xb0
> [10813.312979]  asm_exc_page_fault+0x1e/0x30
> [10813.313978] RIP: 0010:iov_iter_fault_in_readable+0x271/0x350
> fault_in_pages_readable at include/linux/pagemap.h:745
> (inlined by) iov_iter_fault_in_readable at lib/iov_iter.c:438
> [10813.315293] Code: 48 39 d7 0f 82 1a ff ff ff 0f 01 cb 0f ae e8 44 89 c0 8a 0a
> 0f 01 ca 88 4c 24 70 85 c0 74 da e9 f8 fe ff ff 0f 01 cb 0f ae e8 <8a> 11 0f 01
> ca 88 54 24 30 85 c0 0f 85 04 ff ff ff 48 29 ee e9
>  45
> [10813.319196] RSP: 0018:ffffc90017ccf830 EFLAGS: 00050246
> [10813.320446] RAX: 0000000000000000 RBX: 1ffff92002f99f08 RCX: 00007fe284f1004c
> [10813.322202] RDX: 0000000000000001 RSI: 0000000000001000 RDI: ffff8887a7664000
> [10813.323729] RBP: 0000000000001000 R08: 0000000000000000 R09: 0000000000000000
> [10813.325282] R10: ffffc90017ccfd48 R11: ffffed102789d5ff R12: ffff8887a7664020
> [10813.326898] R13: ffffc90017ccfd40 R14: dffffc0000000000 R15: 0000000000e0df6a
> [10813.328456]  ? iov_iter_revert+0x8e0/0x8e0
> [10813.329404]  ? copyin+0x96/0xc0
> [10813.330230]  ? iov_iter_copy_from_user_atomic+0x1f0/0xa40
> [10813.331742]  fuse_perform_write+0x3eb/0xf20 [fuse]
> fuse_fill_write_pages at fs/fuse/file.c:1150
> (inlined by) fuse_perform_write at fs/fuse/file.c:1226
> [10813.332880]  ? fuse_file_fallocate+0x5f0/0x5f0 [fuse]
> [10813.334090]  fuse_file_write_iter+0x6b7/0x900 [fuse]
> [10813.335191]  do_iter_readv_writev+0x42b/0x6d0
> [10813.336161]  ? new_sync_write+0x610/0x610
> [10813.337194]  do_iter_write+0x11f/0x5b0
> [10813.338177]  ? __sb_start_write+0x229/0x2d0
> [10813.339169]  vfs_writev+0x16d/0x2d0
> [10813.339973]  ? vfs_iter_write+0xb0/0xb0
> [10813.340950]  ? __fdget_pos+0x9c/0xb0
> [10813.342039]  ? rcu_read_lock_sched_held+0x9c/0xd0
> [10813.343120]  ? rcu_read_lock_bh_held+0xb0/0xb0
> [10813.344104]  ? find_held_lock+0x33/0x1c0
> [10813.345050]  do_writev+0xfb/0x1e0
> [10813.345920]  ? vfs_writev+0x2d0/0x2d0
> [10813.346802]  ? lockdep_hardirqs_on_prepare+0x27c/0x3d0
> [10813.348026]  ? syscall_enter_from_user_mode+0x1c/0x50
> [10813.349197]  do_syscall_64+0x33/0x40
> [10813.350026]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 18:40 ` Vivek Goyal
@ 2020-10-13 18:58   ` Vivek Goyal
  2020-10-13 19:12     ` Qian Cai
  2020-10-13 19:53     ` Qian Cai
  2020-10-15 13:18   ` Qian Cai
  1 sibling, 2 replies; 9+ messages in thread
From: Vivek Goyal @ 2020-10-13 18:58 UTC (permalink / raw)
  To: Qian Cai
  Cc: Miklos Szeredi, Alexander Viro, Stefan Hajnoczi, linux-fsdevel,
	linux-kernel, virtio-fs

On Tue, Oct 13, 2020 at 02:40:26PM -0400, Vivek Goyal wrote:
> On Tue, Oct 13, 2020 at 01:11:05PM -0400, Qian Cai wrote:
> > Running some fuzzing on virtiofs with an unprivileged user on today's linux-next 
> > could trigger soft-lockups below.
> > 
> > # virtiofsd --socket-path=/tmp/vhostqemu -o source=$TESTDIR -o cache=always -o no_posix_lock
> > 
> > Basically, everything was blocking on inode_lock(inode) because one thread
> > (trinity-c33) was holding it but stuck in the loop in fuse_fill_write_pages()
> > and unable to exit for more than 10 minutes before I executed sysrq-t.
> > Afterwards, the systems was totally unresponsive:
> > 
> > kernel:NMI watchdog: Watchdog detected hard LOCKUP on cpu 8
> > 
> > To exit the loop, it needs,
> > 
> > iov_iter_advance(ii, tmp) to set "tmp" to non-zero for each iteration.
> > 
> > and
> > 
> > 	} while (iov_iter_count(ii) && count < fc->max_write &&
> > 		 ap->num_pages < max_pages && offset == 0);
> > 
> > == the thread is stuck in the loop ==
> > [10813.290694] task:trinity-c33     state:D stack:25888 pid:254219 ppid: 87180
> > flags:0x00004004
> > [10813.292671] Call Trace:
> > [10813.293379]  __schedule+0x71d/0x1b50
> > [10813.294182]  ? __sched_text_start+0x8/0x8
> > [10813.295146]  ? mark_held_locks+0xb0/0x110
> > [10813.296117]  schedule+0xbf/0x270
> > [10813.296782]  ? __lock_page_killable+0x276/0x830
> > [10813.297867]  io_schedule+0x17/0x60
> > [10813.298772]  __lock_page_killable+0x33b/0x830
> 
> This seems to suggest that filemap_fault() is blocked on page lock and
> is sleeping. For some reason it never wakes up. Not sure why.
> 
> And this will be called from.
> 
> fuse_fill_write_pages()
>    iov_iter_fault_in_readable()
> 
> So fuse code will take inode_lock() and then looks like same process
> is sleeping waiting on page lock. And rest of the processes get blocked
> behind inode lock.
> 
> If we are woken up (while waiting on page lock), we should make forward
> progress. Question is what page it is and why the entity which is
> holding lock is not releasing lock.

I am wondering if virtiofsd still alive and responding to requests? I
see another task which is blocked on getdents() for more than 120s.

[10580.142571][  T348] INFO: task trinity-c36:254165 blocked for more than 123
+seconds.
[10580.143924][  T348]       Tainted: G           O	 5.9.0-next-20201013+ #2
[10580.145158][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
+disables this message.
[10580.146636][  T348] task:trinity-c36     state:D stack:26704 pid:254165 ppid:
+87180 flags:0x00000004
[10580.148260][  T348] Call Trace:
[10580.148789][  T348]  __schedule+0x71d/0x1b50
[10580.149532][  T348]  ? __sched_text_start+0x8/0x8
[10580.150343][  T348]  schedule+0xbf/0x270
[10580.151044][  T348]  schedule_preempt_disabled+0xc/0x20
[10580.152006][  T348]  __mutex_lock+0x9f1/0x1360
[10580.152777][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.153484][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
[10580.154432][  T348]  ? find_held_lock+0x33/0x1c0
[10580.155220][  T348]  ? __fdget_pos+0x9c/0xb0
[10580.155934][  T348]  __fdget_pos+0x9c/0xb0
[10580.156660][  T348]  __x64_sys_getdents+0xff/0x230

May be virtiofsd crashed and hence no requests are completing leading
to a hard lockup?

Vivek


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 18:58   ` Vivek Goyal
@ 2020-10-13 19:12     ` Qian Cai
  2020-10-13 19:53     ` Qian Cai
  1 sibling, 0 replies; 9+ messages in thread
From: Qian Cai @ 2020-10-13 19:12 UTC (permalink / raw)
  To: Vivek Goyal
  Cc: Miklos Szeredi, Alexander Viro, Stefan Hajnoczi, linux-fsdevel,
	linux-kernel, virtio-fs

On Tue, 2020-10-13 at 14:58 -0400, Vivek Goyal wrote:
> I am wondering if virtiofsd still alive and responding to requests? I
> see another task which is blocked on getdents() for more than 120s.
> 
> [10580.142571][  T348] INFO: task trinity-c36:254165 blocked for more than 123
> +seconds.
> [10580.143924][  T348]       Tainted: G           O	 5.9.0-next-20201013+ #2
> [10580.145158][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
> +disables this message.
> [10580.146636][  T348] task:trinity-c36     state:D stack:26704 pid:254165
> ppid:
> +87180 flags:0x00000004
> [10580.148260][  T348] Call Trace:
> [10580.148789][  T348]  __schedule+0x71d/0x1b50
> [10580.149532][  T348]  ? __sched_text_start+0x8/0x8
> [10580.150343][  T348]  schedule+0xbf/0x270
> [10580.151044][  T348]  schedule_preempt_disabled+0xc/0x20
> [10580.152006][  T348]  __mutex_lock+0x9f1/0x1360
> [10580.152777][  T348]  ? __fdget_pos+0x9c/0xb0
> [10580.153484][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
> [10580.154432][  T348]  ? find_held_lock+0x33/0x1c0
> [10580.155220][  T348]  ? __fdget_pos+0x9c/0xb0
> [10580.155934][  T348]  __fdget_pos+0x9c/0xb0
> [10580.156660][  T348]  __x64_sys_getdents+0xff/0x230
> 
> May be virtiofsd crashed and hence no requests are completing leading
> to a hard lockup?
No, it was not crashed. After I had to forcibly close the guest, the virtiofsd
daemon will exit normally. However, I can't tell exactly if the virtiofsd daemon
was still functioning normally. I'll enable the debug and retry to see if there
is anything interesting.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 18:58   ` Vivek Goyal
  2020-10-13 19:12     ` Qian Cai
@ 2020-10-13 19:53     ` Qian Cai
  2020-10-13 19:57       ` Vivek Goyal
  2020-10-14  8:26       ` [Virtio-fs] " Dr. David Alan Gilbert
  1 sibling, 2 replies; 9+ messages in thread
From: Qian Cai @ 2020-10-13 19:53 UTC (permalink / raw)
  To: Vivek Goyal
  Cc: Miklos Szeredi, Alexander Viro, Stefan Hajnoczi, linux-fsdevel,
	linux-kernel, virtio-fs

On Tue, 2020-10-13 at 14:58 -0400, Vivek Goyal wrote:

> I am wondering if virtiofsd still alive and responding to requests? I
> see another task which is blocked on getdents() for more than 120s.
> 
> [10580.142571][  T348] INFO: task trinity-c36:254165 blocked for more than 123
> +seconds.
> [10580.143924][  T348]       Tainted: G           O	 5.9.0-next-20201013+ #2
> [10580.145158][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
> +disables this message.
> [10580.146636][  T348] task:trinity-c36     state:D stack:26704 pid:254165
> ppid:
> +87180 flags:0x00000004
> [10580.148260][  T348] Call Trace:
> [10580.148789][  T348]  __schedule+0x71d/0x1b50
> [10580.149532][  T348]  ? __sched_text_start+0x8/0x8
> [10580.150343][  T348]  schedule+0xbf/0x270
> [10580.151044][  T348]  schedule_preempt_disabled+0xc/0x20
> [10580.152006][  T348]  __mutex_lock+0x9f1/0x1360
> [10580.152777][  T348]  ? __fdget_pos+0x9c/0xb0
> [10580.153484][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
> [10580.154432][  T348]  ? find_held_lock+0x33/0x1c0
> [10580.155220][  T348]  ? __fdget_pos+0x9c/0xb0
> [10580.155934][  T348]  __fdget_pos+0x9c/0xb0
> [10580.156660][  T348]  __x64_sys_getdents+0xff/0x230
> 
> May be virtiofsd crashed and hence no requests are completing leading
> to a hard lockup?
Virtiofsd is still working. Once this happened, I manually create a file on the
guest (in virtiofs) and then I can see the content of it from the host.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 19:53     ` Qian Cai
@ 2020-10-13 19:57       ` Vivek Goyal
  2020-10-13 20:10         ` Qian Cai
  2020-10-14  8:26       ` [Virtio-fs] " Dr. David Alan Gilbert
  1 sibling, 1 reply; 9+ messages in thread
From: Vivek Goyal @ 2020-10-13 19:57 UTC (permalink / raw)
  To: Qian Cai
  Cc: Miklos Szeredi, Alexander Viro, Stefan Hajnoczi, linux-fsdevel,
	linux-kernel, virtio-fs

On Tue, Oct 13, 2020 at 03:53:19PM -0400, Qian Cai wrote:
> On Tue, 2020-10-13 at 14:58 -0400, Vivek Goyal wrote:
> 
> > I am wondering if virtiofsd still alive and responding to requests? I
> > see another task which is blocked on getdents() for more than 120s.
> > 
> > [10580.142571][  T348] INFO: task trinity-c36:254165 blocked for more than 123
> > +seconds.
> > [10580.143924][  T348]       Tainted: G           O	 5.9.0-next-20201013+ #2
> > [10580.145158][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
> > +disables this message.
> > [10580.146636][  T348] task:trinity-c36     state:D stack:26704 pid:254165
> > ppid:
> > +87180 flags:0x00000004
> > [10580.148260][  T348] Call Trace:
> > [10580.148789][  T348]  __schedule+0x71d/0x1b50
> > [10580.149532][  T348]  ? __sched_text_start+0x8/0x8
> > [10580.150343][  T348]  schedule+0xbf/0x270
> > [10580.151044][  T348]  schedule_preempt_disabled+0xc/0x20
> > [10580.152006][  T348]  __mutex_lock+0x9f1/0x1360
> > [10580.152777][  T348]  ? __fdget_pos+0x9c/0xb0
> > [10580.153484][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
> > [10580.154432][  T348]  ? find_held_lock+0x33/0x1c0
> > [10580.155220][  T348]  ? __fdget_pos+0x9c/0xb0
> > [10580.155934][  T348]  __fdget_pos+0x9c/0xb0
> > [10580.156660][  T348]  __x64_sys_getdents+0xff/0x230
> > 
> > May be virtiofsd crashed and hence no requests are completing leading
> > to a hard lockup?
> Virtiofsd is still working. Once this happened, I manually create a file on the
> guest (in virtiofs) and then I can see the content of it from the host.

Hmm..., So how do I reproduce it. Just run trinity as root and it will
reproduce after some time?

Vivek


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 19:57       ` Vivek Goyal
@ 2020-10-13 20:10         ` Qian Cai
  0 siblings, 0 replies; 9+ messages in thread
From: Qian Cai @ 2020-10-13 20:10 UTC (permalink / raw)
  To: Vivek Goyal
  Cc: Miklos Szeredi, Alexander Viro, Stefan Hajnoczi, linux-fsdevel,
	linux-kernel, virtio-fs

On Tue, 2020-10-13 at 15:57 -0400, Vivek Goyal wrote:
> Hmm..., So how do I reproduce it. Just run trinity as root and it will
> reproduce after some time?

Only need to run it as unprivileged user after mounting virtiofs on /tmp
(trinity will need to create and use files there) as many as CPUs as possible.
Also, make sure your guest's memory usage does not exceed the host's /dev/shm
size. Otherwise, horrible things could happen.

$ trinity -C 48 --arch 64

It might get coredump or exit due to some other unrelated reasons, so just keep
retrying. It is best to apply your recent patch for the virtiofs false positive
warning first, so it won't taint the kernel which will stop the trinity. Today,
I had been able to reproduce it twice within half-hour each.




^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Virtio-fs] Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 19:53     ` Qian Cai
  2020-10-13 19:57       ` Vivek Goyal
@ 2020-10-14  8:26       ` Dr. David Alan Gilbert
  1 sibling, 0 replies; 9+ messages in thread
From: Dr. David Alan Gilbert @ 2020-10-14  8:26 UTC (permalink / raw)
  To: Qian Cai
  Cc: Vivek Goyal, Miklos Szeredi, linux-kernel, virtio-fs,
	Alexander Viro, linux-fsdevel

* Qian Cai (cai@redhat.com) wrote:
> On Tue, 2020-10-13 at 14:58 -0400, Vivek Goyal wrote:
> 
> > I am wondering if virtiofsd still alive and responding to requests? I
> > see another task which is blocked on getdents() for more than 120s.
> > 
> > [10580.142571][  T348] INFO: task trinity-c36:254165 blocked for more than 123
> > +seconds.
> > [10580.143924][  T348]       Tainted: G           O	 5.9.0-next-20201013+ #2
> > [10580.145158][  T348] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
> > +disables this message.
> > [10580.146636][  T348] task:trinity-c36     state:D stack:26704 pid:254165
> > ppid:
> > +87180 flags:0x00000004
> > [10580.148260][  T348] Call Trace:
> > [10580.148789][  T348]  __schedule+0x71d/0x1b50
> > [10580.149532][  T348]  ? __sched_text_start+0x8/0x8
> > [10580.150343][  T348]  schedule+0xbf/0x270
> > [10580.151044][  T348]  schedule_preempt_disabled+0xc/0x20
> > [10580.152006][  T348]  __mutex_lock+0x9f1/0x1360
> > [10580.152777][  T348]  ? __fdget_pos+0x9c/0xb0
> > [10580.153484][  T348]  ? mutex_lock_io_nested+0x1240/0x1240
> > [10580.154432][  T348]  ? find_held_lock+0x33/0x1c0
> > [10580.155220][  T348]  ? __fdget_pos+0x9c/0xb0
> > [10580.155934][  T348]  __fdget_pos+0x9c/0xb0
> > [10580.156660][  T348]  __x64_sys_getdents+0xff/0x230
> > 
> > May be virtiofsd crashed and hence no requests are completing leading
> > to a hard lockup?
> Virtiofsd is still working. Once this happened, I manually create a file on the
> guest (in virtiofs) and then I can see the content of it from the host.

If the virtiofsd is still running, attach gdb to it and get a full bt;

gdb --pid  whatever

(gdb) t a a bt full

that should show if it's stuck in one particular place.

Dave


> _______________________________________________
> Virtio-fs mailing list
> Virtio-fs@redhat.com
> https://www.redhat.com/mailman/listinfo/virtio-fs
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Unbreakable loop in fuse_fill_write_pages()
  2020-10-13 18:40 ` Vivek Goyal
  2020-10-13 18:58   ` Vivek Goyal
@ 2020-10-15 13:18   ` Qian Cai
  1 sibling, 0 replies; 9+ messages in thread
From: Qian Cai @ 2020-10-15 13:18 UTC (permalink / raw)
  To: Vivek Goyal, Miklos Szeredi
  Cc: Alexander Viro, Stefan Hajnoczi, linux-fsdevel, linux-kernel, virtio-fs

On Tue, 2020-10-13 at 14:40 -0400, Vivek Goyal wrote:
> > == the thread is stuck in the loop ==
> > [10813.290694] task:trinity-c33     state:D stack:25888 pid:254219 ppid:
> > 87180
> > flags:0x00004004
> > [10813.292671] Call Trace:
> > [10813.293379]  __schedule+0x71d/0x1b50
> > [10813.294182]  ? __sched_text_start+0x8/0x8
> > [10813.295146]  ? mark_held_locks+0xb0/0x110
> > [10813.296117]  schedule+0xbf/0x270
> > [10813.296782]  ? __lock_page_killable+0x276/0x830
> > [10813.297867]  io_schedule+0x17/0x60
> > [10813.298772]  __lock_page_killable+0x33b/0x830
> 
> This seems to suggest that filemap_fault() is blocked on page lock and
> is sleeping. For some reason it never wakes up. Not sure why.
> 
> And this will be called from.
> 
> fuse_fill_write_pages()
>    iov_iter_fault_in_readable()
> 
> So fuse code will take inode_lock() and then looks like same process
> is sleeping waiting on page lock. And rest of the processes get blocked
> behind inode lock.
> 
> If we are woken up (while waiting on page lock), we should make forward
> progress. Question is what page it is and why the entity which is
> holding lock is not releasing lock.

FYI, it was mentioned that this is likely a deadlock in FUSE:

https://lore.kernel.org/linux-fsdevel/CAHk-=wh9Eu-gNHzqgfvUAAiO=vJ+pWnzxkv+tX55xhGPFy+cOw@mail.gmail.com/




^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, back to index

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-13 17:11 Unbreakable loop in fuse_fill_write_pages() Qian Cai
2020-10-13 18:40 ` Vivek Goyal
2020-10-13 18:58   ` Vivek Goyal
2020-10-13 19:12     ` Qian Cai
2020-10-13 19:53     ` Qian Cai
2020-10-13 19:57       ` Vivek Goyal
2020-10-13 20:10         ` Qian Cai
2020-10-14  8:26       ` [Virtio-fs] " Dr. David Alan Gilbert
2020-10-15 13:18   ` Qian Cai

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