From: Michal Hocko <mhocko@kernel.org>
To: Roman Gushchin <guro@fb.com>
Cc: Dexuan Cui <decui@microsoft.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Shakeel Butt <shakeelb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Rik van Riel <riel@surriel.com>,
Konstantin Khlebnikov <koct9i@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
"Stable@vger.kernel.org" <Stable@vger.kernel.org>
Subject: Re: Will the recent memory leak fixes be backported to longterm kernels?
Date: Fri, 2 Nov 2018 18:48:23 +0100 [thread overview]
Message-ID: <20181102174823.GI28039@dhcp22.suse.cz> (raw)
In-Reply-To: <20181102172547.GA19042@tower.DHCP.thefacebook.com>
On Fri 02-11-18 17:25:58, Roman Gushchin wrote:
> On Fri, Nov 02, 2018 at 05:51:47PM +0100, Michal Hocko wrote:
> > On Fri 02-11-18 16:22:41, Roman Gushchin wrote:
[...]
> > > 2) We do forget to scan the last page in the LRU list. So if we ended up with
> > > 1-page long LRU, it can stay there basically forever.
> >
> > Why
> > /*
> > * If the cgroup's already been deleted, make sure to
> > * scrape out the remaining cache.
> > */
> > if (!scan && !mem_cgroup_online(memcg))
> > scan = min(size, SWAP_CLUSTER_MAX);
> >
> > in get_scan_count doesn't work for that case?
>
> No, it doesn't. Let's look at the whole picture:
>
> size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
> scan = size >> sc->priority;
> /*
> * If the cgroup's already been deleted, make sure to
> * scrape out the remaining cache.
> */
> if (!scan && !mem_cgroup_online(memcg))
> scan = min(size, SWAP_CLUSTER_MAX);
>
> If size == 1, scan == 0 => scan = min(1, 32) == 1.
> And after proportional adjustment we'll have 0.
My friday brain hurst when looking at this but if it doesn't work as
advertized then it should be fixed. I do not see any of your patches to
touch this logic so how come it would work after them applied?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-11-02 17:48 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-02 0:16 Will the recent memory leak fixes be backported to longterm kernels? Dexuan Cui
2018-11-02 0:45 ` Sasha Levin
2018-11-02 0:58 ` Roman Gushchin
2018-11-02 2:45 ` Dexuan Cui
2018-11-02 3:16 ` Roman Gushchin
2018-11-02 8:03 ` Michal Hocko
2018-11-02 15:48 ` Roman Gushchin
2018-11-02 16:13 ` Michal Hocko
2018-11-02 16:22 ` Roman Gushchin
2018-11-02 16:51 ` Michal Hocko
2018-11-02 17:25 ` Roman Gushchin
2018-11-02 17:48 ` Michal Hocko [this message]
2018-11-02 19:38 ` Roman Gushchin
2018-11-05 9:21 ` Michal Hocko
2018-12-28 10:50 ` Greg KH
2019-01-30 0:23 ` Sasha Levin
2019-01-30 5:58 ` Roman Gushchin
2018-11-02 16:01 ` Sasha Levin
2018-11-04 9:16 ` Mike Rapoport
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