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From:   Justin Piszcz <jpiszcz@lucidpixels.com>
Date:   Thu, 16 May 2019 10:14:10 -0400
Message-ID: <CAO9zADww2v2ckHsNDwRgiyMr9b3JH1xOOSiRJ0Uh2XZT5c=MEQ@mail.gmail.com>
Subject: Re: 5.1 kernel: khugepaged stuck at 100%
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     LKML <linux-kernel@vger.kernel.org>
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On Tue, May 14, 2019 at 9:16 AM Kirill A. Shutemov <kirill@shutemov.name> wrote:

> Could you check what khugepaged doing?
>
> cat /proc/$(pidof khugepaged)/stack

It is doing it again, 10:12am - 2019-05-16

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
   77 root      39  19       0      0      0 R 100.0   0.0  92:06.94 khugepaged

Kernel: 5.1.2

$ sudo cat /proc/$(pidof khugepaged)/stack
[<0>] 0xffffffffffffffff

$ perf top

   PerfTop:    3716 irqs/sec  kernel:92.9%  exact: 99.1% lost: 68/68
drop: 0/0 [4000Hz cycles],  (all, 12 CPUs)
-------------------------------------------------------------------------------

    47.53%  [kernel]                 [k] compaction_alloc
    38.88%  [kernel]                 [k] __pageblock_pfn_to_page
     6.68%  [kernel]                 [k] nmi
     0.58%  [kernel]                 [k] __list_del_entry_valid
     0.48%  [kernel]                 [k] format_decode
     0.39%  [kernel]                 [k] __rb_insert_augmented
     0.25%  libdbus-1.so.3.19.9      [.] _dbus_string_hex_decode
     0.24%  [kernel]                 [k] entry_SYSCALL_64_after_hwframe
     0.20%  perf                     [.] rb_next
     0.19%  perf                     [.] __symbols__insert