From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Oscar Salvador <OSalvador@suse.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
David Hildenbrand <david@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [RFC PATCH 3/3] mm, fault_around: do not take a reference to a locked page
Date: Tue, 20 Nov 2018 17:07:15 +0300 [thread overview]
Message-ID: <20181120140715.mouc7okin3ht5krr@kshutemo-mobl1> (raw)
In-Reply-To: <20181120134323.13007-4-mhocko@kernel.org>
On Tue, Nov 20, 2018 at 02:43:23PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> filemap_map_pages takes a speculative reference to each page in the
> range before it tries to lock that page. While this is correct it
> also can influence page migration which will bail out when seeing
> an elevated reference count. The faultaround code would bail on
> seeing a locked page so we can pro-actively check the PageLocked
> bit before page_cache_get_speculative and prevent from pointless
> reference count churn.
Looks fine to me.
But please drop a line of comment in the code. As is it might be confusing
for a reader.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2018-11-20 14:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 13:43 [RFC PATCH 0/3] few memory offlining enhancements Michal Hocko
2018-11-20 13:43 ` Michal Hocko
2018-11-20 13:43 ` [RFC PATCH 1/3] mm, memory_hotplug: try to migrate full section worth of pages Michal Hocko
2018-11-20 13:43 ` Michal Hocko
2018-11-20 14:18 ` David Hildenbrand
2018-11-20 14:25 ` Michal Hocko
2018-11-20 14:27 ` David Hildenbrand
2018-11-20 14:33 ` Pavel Tatashin
2018-11-20 14:51 ` osalvador
2018-11-20 15:00 ` Michal Hocko
2018-11-20 13:43 ` [RFC PATCH 2/3] mm, memory_hotplug: deobfuscate migration part of offlining Michal Hocko
2018-11-20 13:43 ` Michal Hocko
2018-11-20 14:26 ` David Hildenbrand
2018-11-20 14:34 ` Michal Hocko
2018-11-20 14:34 ` David Hildenbrand
2018-11-20 15:13 ` osalvador
2018-11-20 15:18 ` Michal Hocko
2018-11-20 13:43 ` [RFC PATCH 3/3] mm, fault_around: do not take a reference to a locked page Michal Hocko
2018-11-20 13:43 ` Michal Hocko
2018-11-20 14:07 ` Kirill A. Shutemov [this message]
2018-11-20 14:12 ` Michal Hocko
2018-11-20 14:17 ` Kirill A. Shutemov
2018-11-20 14:25 ` Michal Hocko
2018-11-21 4:51 ` William Kucharski
2018-11-21 7:07 ` Michal Hocko
2018-11-20 14:33 ` David Hildenbrand
2018-11-21 1:47 ` Hugh Dickins
2018-11-21 7:11 ` Michal Hocko
2018-11-22 2:27 ` Hugh Dickins
2018-11-22 9:05 ` Michal Hocko
2018-11-23 20:22 ` Hugh Dickins
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