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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	xfs@oss.sgi.com, Linux-MM <linux-mm@kvack.org>,
	Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	ppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 3/4] mm: numa: Mark huge PTEs young when clearing NUMA hinting faults
Date: Sat, 7 Mar 2015 10:42:29 -0800	[thread overview]
Message-ID: <CA+55aFxwmysVRCkBKFA88m_h0Byb0-2QvWn0_2rb_QNb8Eeedg@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFwSQgrYqfXPr6RPvQ+8OJfexXJRY_GVEKg5QtB2t38cWA@mail.gmail.com>

On Sat, Mar 7, 2015 at 10:33 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
>             Completely untested, but that "just
> or in the new protection bits" is what pnf_pte() does just a few lines
> above this.

Hmm. Looking at this, we do *not* want to set _PAGE_ACCESSED when we
turn a page into PROT_NONE or mark it for numa faulting. Nor do we
want to set it for mprotect for random pages that we haven't actually
accessed, just changed the protections for.

So my patch was obviously wrong, and I should feel bad for suggesting
it. I'm a moron, and my expectations that "pte_modify()" would just
take the accessed bit from the vm_page_prot field was stupid and
wrong.

Mel's patch is the right thing to do.

                                Linus

  reply	other threads:[~2015-03-07 18:42 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-07 15:20 [RFC PATCH 0/4] Automatic NUMA balancing and PROT_NONE handling followup v2r8 Mel Gorman
2015-03-07 15:20 ` [PATCH 1/4] mm: thp: Return the correct value for change_huge_pmd Mel Gorman
2015-03-07 20:13   ` Linus Torvalds
2015-03-07 20:31   ` Linus Torvalds
2015-03-07 20:56     ` Mel Gorman
2015-03-07 15:20 ` [PATCH 2/4] mm: numa: Remove migrate_ratelimited Mel Gorman
2015-03-07 15:20 ` [PATCH 3/4] mm: numa: Mark huge PTEs young when clearing NUMA hinting faults Mel Gorman
2015-03-07 18:33   ` Linus Torvalds
2015-03-07 18:42     ` Linus Torvalds [this message]
2015-03-07 15:20 ` [PATCH 4/4] mm: numa: Slow PTE scan rate if migration failures occur Mel Gorman
2015-03-07 16:36   ` Ingo Molnar
2015-03-07 17:37     ` Mel Gorman
2015-03-08  9:54       ` Ingo Molnar
2015-03-07 19:12     ` Linus Torvalds
2015-03-08 10:02       ` Ingo Molnar
2015-03-08 18:35         ` Linus Torvalds
2015-03-08 18:46           ` Linus Torvalds
2015-03-09 11:29           ` Dave Chinner
2015-03-09 16:52             ` Linus Torvalds
2015-03-09 19:19               ` Dave Chinner
2015-03-10 23:55                 ` Linus Torvalds
2015-03-12 13:10                   ` Mel Gorman
2015-03-12 16:20                     ` Linus Torvalds
2015-03-12 18:49                       ` Mel Gorman
2015-03-17  7:06                         ` Dave Chinner
2015-03-17 16:53                           ` Linus Torvalds
2015-03-17 20:51                             ` Dave Chinner
2015-03-17 21:30                               ` Linus Torvalds
2015-03-17 22:08                                 ` Dave Chinner
2015-03-18 16:08                                   ` Linus Torvalds
2015-03-18 17:31                                     ` Linus Torvalds
2015-03-18 22:23                                       ` Dave Chinner
2015-03-19 14:10                                       ` Mel Gorman
2015-03-19 18:09                                         ` Linus Torvalds
2015-03-19 21:41                                       ` Linus Torvalds
2015-03-19 22:41                                         ` Dave Chinner
2015-03-19 23:05                                           ` Linus Torvalds
2015-03-19 23:23                                             ` Dave Chinner
2015-03-20  0:23                                             ` Dave Chinner
2015-03-20  1:29                                               ` Linus Torvalds
2015-03-20  4:13                                                 ` Dave Chinner
2015-03-20 17:02                                                   ` Linus Torvalds
2015-03-23 12:01                                                     ` Mel Gorman
2015-03-20 10:12                                                 ` Mel Gorman
2015-03-20  9:56                                             ` Mel Gorman
2015-03-08 20:40         ` Mel Gorman
2015-03-09 21:02           ` Mel Gorman
2015-03-10 13:08             ` Mel Gorman
2015-03-08  9:41   ` Ingo Molnar

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