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Message-ID: <20140930160729.GB15903@redhat.com> Date: Tue, 30 Sep 2014 12:07:29 -0400 From: Dave Jones <davej@...hat.com> To: Rik van Riel <riel@...hat.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org>, Al Viro <viro@...iv.linux.org.uk>, Linux Kernel <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>, Michel Lespinasse <walken@...gle.com> Subject: Re: pipe/page fault oddness. 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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