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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Jones <davej@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@redhat.com>,
	Michel Lespinasse <walken@google.com>
Subject: Re: pipe/page fault oddness.
Date: Tue, 30 Sep 2014 09:10:26 -0700	[thread overview]
Message-ID: <CA+55aFzTEXxxh_4_BwVydw1UgCu-NRF95OrzVhj=cievXFTJTg@mail.gmail.com> (raw)
In-Reply-To: <20140930160510.GA15903@redhat.com>

On Tue, Sep 30, 2014 at 9:05 AM, Dave Jones <davej@redhat.com> wrote:
>
> I left it spinning overnight in case someone wanted me to probe it
> further, so I haven't tried reproducing it yet.  It took ~12 hours
> yesterday before it got in that state.  I'll restart it, and tell it
> to only use pipe fd's, which might speed things up a little.

Actually, if you haven't restarted it yet, do a few more "Sysrq-T"'s
to see if the stack below the page fault ever changes. Is it *always*
that "second access by fault_in_pages_writeable()" or migth there be
some looping going on in copy_page_to_iter() after all? (Quite
frankly, I don't see how such looping could happen with a good
compiler, and 4.8.3 should be good, but just in case).

It's an unlikely scenario, so if you already rebooted, not a big deal.

> model name      : Intel(R) Core(TM) i5-4670T CPU @ 2.30GHz

Ok, that pretty much throws the "maybe AMD did something different"
theory out of the water. Something subtler. Still worth trying the
revert.

            Linus

  reply	other threads:[~2014-09-30 16:10 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-30  3:33 pipe/page fault oddness Dave Jones
2014-09-30  4:27 ` Linus Torvalds
2014-09-30  4:33   ` Dave Jones
     [not found]     ` <CA+55aFwxdOBKHwwp7Zq1k19mHCyHYmYqigCVt59AtB-P7Zva1w@mail.gmail.com>
2014-09-30 15:52       ` Linus Torvalds
2014-09-30 16:03         ` Rik van Riel
2014-09-30 16:07           ` Dave Jones
2014-09-30 16:26           ` Linus Torvalds
2014-09-30 16:05         ` Dave Jones
2014-09-30 16:10           ` Linus Torvalds [this message]
2014-09-30 16:22             ` Dave Jones
2014-09-30 16:40               ` Dave Jones
2014-09-30 16:46                 ` Linus Torvalds
2014-09-30 18:20                   ` Dave Jones
2014-09-30 18:58                     ` Linus Torvalds
2014-10-01  8:19                       ` Hugh Dickins
2014-10-01 16:01                         ` Linus Torvalds
2014-10-01 16:18                           ` Linus Torvalds
2014-10-01 17:29                             ` Rik van Riel
2014-10-02  8:28                               ` Peter Zijlstra
2014-10-01 20:20                             ` Linus Torvalds
2014-10-01 21:09                               ` Rik van Riel
2014-10-01 22:08                               ` Sasha Levin
2014-10-01 22:28                                 ` Chuck Ebbert
2014-10-02  3:32                                   ` Sasha Levin
2014-10-02  8:03                                     ` Chuck Ebbert
2014-10-02 14:49                                       ` Sasha Levin
2014-10-01 22:42                                 ` Linus Torvalds
2014-10-02 14:25                                   ` Kirill A. Shutemov
2014-10-02 16:01                                     ` Linus Torvalds
2014-10-02 16:35                                       ` Kirill A. Shutemov
2014-10-02 15:04                                   ` Sasha Levin
2014-10-02 16:10                                     ` Linus Torvalds
2014-10-03  5:00                                       ` Sasha Levin
2014-10-03 15:43                                         ` Linus Torvalds
2014-10-03 15:58                                           ` Dave Jones
2014-10-03 16:02                                             ` Sasha Levin
2014-10-02 12:45                             ` Mel Gorman
2014-10-06 19:18                               ` Aneesh Kumar K.V
2014-10-07 12:45                                 ` Linus Torvalds
2014-10-08 10:37                                   ` Aneesh Kumar K.V
2014-10-02  8:47                           ` Hugh Dickins
2014-10-02 15:57                             ` Linus Torvalds
2014-09-30  4:35   ` Al Viro

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