From: Dave Jones <davej@redhat.com>
To: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Michel Lespinasse <walken@google.com>
Subject: Re: pipe/page fault oddness.
Date: Tue, 30 Sep 2014 12:07:29 -0400 [thread overview]
Message-ID: <20140930160729.GB15903@redhat.com> (raw)
In-Reply-To: <542AD43A.90706@redhat.com>
On Tue, Sep 30, 2014 at 12:03:06PM -0400, Rik van Riel wrote:
> > What kind of CPU is the problematic machine? There was some
> > question about just how architectural the whole "TLB entry causing
> > a page fault gets invalidated automatically" really is.
>
> Intel people told me at the time that the guarantee was architectural.
> I don't know whether other x86 manufacturers know this...
>
> Doing a local tlb flush from ptep_set_access_flags seems appropriate,
> if that is indeed the issue.
>
> On the other hand, do_wp_page does not seem to do a tlb flush when
> the old page is reused, so CPUs do get rid of inappropriate TLB
> entries. We would have noticed do_wp_page not working right :)
The puzzling thing is we've had that code change for two years
without issue. This isn't a new machine, so why would it only
be showing up bad effects now ?
Dave
next prev parent reply other threads:[~2014-09-30 16:07 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 [this message]
2014-09-30 16:26 ` Linus Torvalds
2014-09-30 16:05 ` Dave Jones
2014-09-30 16:10 ` Linus Torvalds
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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