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From: David Vrabel <david.vrabel@citrix.com>
To: David Vrabel <david.vrabel@citrix.com>
Cc: Steven Noonan <steven@uplinklabs.net>,
	Mel Gorman <mgorman@suse.de>,
	Elena Ufimtseva <ufimtseva@gmail.com>,
	xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH 2/2] x86: use pv-ops in {pte, pmd}_{set, clear}_flags()
Date: Mon, 24 Mar 2014 11:28:11 +0000	[thread overview]
Message-ID: <533016CB.4090807@citrix.com> (raw)
In-Reply-To: <1395425902-29817-3-git-send-email-david.vrabel@citrix.com>

On 21/03/14 18:18, David Vrabel wrote:
> Instead of using native functions to operate on the PTEs in
> pte_set_flags(), pte_clear_flags(), pmd_set_flags(), pmd_clear_flags()
> use the PV aware ones.

Looking at the history of this changes, these were introduced to avoid
PV ops for performance reasons.

I believe this can be fixed by making the numa-related PTE modifier
functions (pte_mknuma(), pte_mknonnuma()) use pte_modify() which is the
correct function to use when adjusting page protection.

I really do not understand how you're supposed to distinguish between a
PTE for a PROT_NONE page and one with _PAGE_NUMA -- they're identical.
i.e., pte_numa() will return true for a PROT_NONE protected page which
just seems wrong to me.

David

  reply	other threads:[~2014-03-24 11:28 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-21 18:18 [RFC PATCH 0/2] x86: fix Xen PV regression caused by NUMA page migration David Vrabel
2014-03-21 18:18 ` [PATCH 1/2] Revert "xen: properly account for _PAGE_NUMA during xen pte translations" David Vrabel
2014-03-21 18:18 ` [PATCH 2/2] x86: use pv-ops in {pte, pmd}_{set, clear}_flags() David Vrabel
2014-03-24 11:28   ` David Vrabel [this message]
     [not found]     ` <CAKbGBLiVqaHEOZx6y4MW4xDTUdKRhVLZXTTGiqYT7vuH2Wgeww@mail.gmail.com>
2014-03-25 20:16       ` [PATCH 2/2] x86: use pv-ops in {pte,pmd}_{set,clear}_flags() Linus Torvalds
2014-03-31 12:26         ` Mel Gorman
2014-03-31 15:41           ` Linus Torvalds
2014-03-31 16:10             ` Linus Torvalds
2014-03-31 16:27               ` Cyrill Gorcunov
2014-04-01 18:18             ` David Vrabel
2014-04-01 18:43               ` Linus Torvalds
2014-04-01 19:03                 ` Cyrill Gorcunov
2014-04-02 11:33                   ` Pavel Emelyanov
2014-04-02 13:29                     ` Cyrill Gorcunov
2014-03-26 19:10 ` [RFC PATCH 0/2] x86: fix Xen PV regression caused by NUMA page migration David Vrabel
2014-04-15  8:24 ` David Sutton

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