From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
Arun KS <arunks@codeaurora.org>,
keescook@chromium.org, minchan@kernel.org, getarunks@gmail.com,
gregkh@linuxfoundation.org, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
julia.lawall@lip6.fr
Subject: Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and managed pages to atomic
Date: Wed, 7 Nov 2018 11:28:37 +0100 [thread overview]
Message-ID: <20181107102837.GC27423@dhcp22.suse.cz> (raw)
In-Reply-To: <89a259aa-156e-041c-b3bc-266824acb173@suse.cz>
On Wed 07-11-18 09:50:10, Vlastimil Babka wrote:
> On 11/7/18 8:02 AM, Konstantin Khlebnikov wrote:
[...]
> > Could you point what exactly are you fixing with this set?
> >
> > from v2:
> >
> > > totalram_pages, zone->managed_pages and totalhigh_pages updates
> > > are protected by managed_page_count_lock, but readers never care
> > > about it. Convert these variables to atomic to avoid readers
> > > potentially seeing a store tear.
> >
> > This?
> >
> >
> > Aligned unsigned long almost always stored at once.
>
> The point is "almost always", so better not rely on it :) But the main
> motivation was that managed_page_count_lock handling was complicating
> Arun's "memory_hotplug: Free pages as higher order" patch and it seemed
> a better idea to just remove and convert this to atomics, with
> preventing potential store-to-read tearing as a bonus.
And more importantly the lock itself seems bogus as mentioned here
http://lkml.kernel.org/r/20181106141732.GR27423@dhcp22.suse.cz
> It would be nice to mention it in the changelogs though.
agreed
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-11-07 10:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-26 11:00 [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and managed pages to atomic Arun KS
2018-10-26 11:00 ` [PATCH v1 1/4] mm: Fix multiple evaluvations of totalram_pages and managed_pages Arun KS
2018-10-26 11:01 ` [PATCH v1 2/4] mm: Convert zone->managed_pages to atomic variable Arun KS
2018-10-26 11:01 ` [PATCH v1 3/4] mm: convert totalram_pages and totalhigh_pages variables to atomic Arun KS
[not found] ` <20181106141438.GQ27423@dhcp22.suse.cz>
2018-11-07 10:38 ` Michal Hocko
2018-10-26 11:01 ` [PATCH v1 4/4] mm: Remove managed_page_count spinlock Arun KS
[not found] ` <20181106141732.GR27423@dhcp22.suse.cz>
2018-11-07 10:36 ` Michal Hocko
2018-11-07 11:50 ` Vlastimil Babka
2018-11-06 5:38 ` [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and managed pages to atomic Arun KS
2018-11-06 8:17 ` Konstantin Khlebnikov
2018-11-06 8:30 ` Arun KS
2018-11-06 8:37 ` Konstantin Khlebnikov
2018-11-06 8:43 ` Arun KS
2018-11-07 7:02 ` Konstantin Khlebnikov
2018-11-07 8:50 ` Vlastimil Babka
2018-11-07 10:28 ` Michal Hocko [this message]
2018-11-07 10:39 ` Michal Hocko
2018-11-07 0:22 ` Andrew Morton
2018-11-07 6:19 ` Arun KS
-- strict thread matches above, loose matches on Subject: below --
2018-10-26 11:00 Arun KS
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