On 02/09/2014 08:41 PM, Sasha Levin wrote:

On 02/08/2014 10:25 PM, Hugh Dickins wrote:

quoted

Would trinity be likely to have a thread or process repeatedly faulting
in pages from the hole while it is being punched?

I can see how trinity would do that, but just to be certain - Cc davej.

On 02/08/2014 10:25 PM, Hugh Dickins wrote:

quoted

Does this happen with other holepunch filesystems?  If it does not,
I'd suppose it's because the tmpfs fault-in-newly-created-page path
is lighter than a consistent disk-based filesystem's has to be.
But we don't want to make the tmpfs path heavier to match them.

No, this is strictly limited to tmpfs, and AFAIK trinity tests hole
punching in other filesystems and I make sure to get a bunch of those
mounted before starting testing.

Just pinging this one again. I still see hangs in -next where the hang
location looks same as before:


[ 3602.443529] CPU: 6 PID: 1153 Comm: trinity-c35 Not tainted 3.15.0-next-20140612-sasha-00022-g5e4db85-dirty #645
[ 3602.443529] task: ffff8801b45eb000 ti: ffff8801a0b90000 task.ti: ffff8801a0b90000
[ 3602.443529] RIP: vtime_account_system (include/linux/seqlock.h:229 include/linux/seqlock.h:234 include/linux/seqlock.h:301 kernel/sched/cputime.c:664)
[ 3602.443529] RSP: 0018:ffff8801b4e03ef8  EFLAGS: 00000046
[ 3602.443529] RAX: ffffffffb31a83b8 RBX: ffff8801b45eb000 RCX: 0000000000000001
[ 3602.443529] RDX: ffffffffb31a80bb RSI: ffffffffb7915a75 RDI: 0000000000000082
[ 3602.443529] RBP: ffff8801b4e03f28 R08: 0000000000000001 R09: 0000000000000000
[ 3602.443529] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b45eb968
[ 3602.443529] R13: ffff8801b45eb938 R14: 0000000000000282 R15: ffff8801b45ebda0
[ 3602.443529] FS:  00007f93ac8ec700(0000) GS:ffff8801b4e00000(0000) knlGS:0000000000000000
[ 3602.443529] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3602.443529] CR2: 00007f93a8854c9f CR3: 000000018a189000 CR4: 00000000000006a0
[ 3602.443529] Stack:
[ 3602.443529]  ffff8801b45eb000 00000000001d7800 ffffffffb32bd749 ffff8801b45eb000
[ 3602.443529]  00000000001d7800 ffffffffb32bd749 ffff8801b4e03f48 ffffffffb31a83b8
[ 3602.443529]  ffff8801b4e03f48 ffff8801b45eb000 ffff8801b4e03f68 ffffffffb31666a0
[ 3602.443529] Call Trace:
[ 3602.443529]  <IRQ>
[ 3602.443529] vtime_common_account_irq_enter (kernel/sched/cputime.c:430)
[ 3602.443529] irq_enter (include/linux/vtime.h:63 include/linux/vtime.h:115 kernel/softirq.c:334)
[ 3602.443529] scheduler_ipi (kernel/sched/core.c:1589 include/linux/jump_label.h:115 include/linux/context_tracking_state.h:27 include/linux/tick.h:168 include/linux/tick.h:199 kernel/sched/core.c:1590)
[ 3602.443529] smp_reschedule_interrupt (arch/x86/kernel/smp.c:266)
[ 3602.443529] reschedule_interrupt (arch/x86/kernel/entry_64.S:1046)
[ 3602.443529]  <EOI>
[ 3602.443529] _raw_spin_unlock (include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:183)
[ 3602.443529] zap_pte_range (mm/memory.c:1218)
[ 3602.443529] unmap_single_vma (mm/memory.c:1256 mm/memory.c:1277 mm/memory.c:1302 mm/memory.c:1348)
[ 3602.443529] zap_page_range_single (include/linux/mmu_notifier.h:234 mm/memory.c:1429)
[ 3602.443529] unmap_mapping_range (mm/memory.c:2316 mm/memory.c:2392)
[ 3602.443529] truncate_inode_page (mm/truncate.c:136 mm/truncate.c:180)
[ 3602.443529] shmem_undo_range (mm/shmem.c:429)
[ 3602.443529] shmem_truncate_range (mm/shmem.c:527)
[ 3602.443529] shmem_fallocate (mm/shmem.c:1740)
[ 3602.443529] do_fallocate (include/linux/fs.h:1281 fs/open.c:299)
[ 3602.443529] SyS_madvise (mm/madvise.c:335 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
[ 3602.443529] tracesys (arch/x86/kernel/entry_64.S:542)
[ 3602.443529] Code: 09 00 00 48 89 5d e8 48 89 fb 4c 89 e7 4c 89 6d f8 e8 25 69 3b 03 83 83 30 09 00 00 01 48 8b 45 08 4c 8d ab 38 09 00 00 45 31 c9 <41> b8 01 00 00 00 31 c9 31 d2 31 f6 4c 89 ef 48 89 04 24 e8 e8
All code
========
   0:   09 00                   or     %eax,(%rax)
   2:   00 48 89                add    %cl,-0x77(%rax)
   5:   5d                      pop    %rbp
   6:   e8 48 89 fb 4c          callq  0x4cfb8953
   b:   89 e7                   mov    %esp,%edi
   d:   4c 89 6d f8             mov    %r13,-0x8(%rbp)
  11:   e8 25 69 3b 03          callq  0x33b693b
  16:   83 83 30 09 00 00 01    addl   $0x1,0x930(%rbx)
  1d:   48 8b 45 08             mov    0x8(%rbp),%rax
  21:   4c 8d ab 38 09 00 00    lea    0x938(%rbx),%r13
  28:   45 31 c9                xor    %r9d,%r9d
  2b:*  41 b8 01 00 00 00       mov    $0x1,%r8d                <-- trapping instruction
  31:   31 c9                   xor    %ecx,%ecx
  33:   31 d2                   xor    %edx,%edx
  35:   31 f6                   xor    %esi,%esi
  37:   4c 89 ef                mov    %r13,%rdi
  3a:   48 89 04 24             mov    %rax,(%rsp)
  3e:   e8                      .byte 0xe8
  3f:   e8                      .byte 0xe8
        ...

Code starting with the faulting instruction
===========================================
   0:   41 b8 01 00 00 00       mov    $0x1,%r8d
   6:   31 c9                   xor    %ecx,%ecx
   8:   31 d2                   xor    %edx,%edx
   a:   31 f6                   xor    %esi,%esi
   c:   4c 89 ef                mov    %r13,%rdi
   f:   48 89 04 24             mov    %rax,(%rsp)
  13:   e8                      .byte 0xe8
  14:   e8                      .byte 0xe8


Thanks,
Sasha

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