From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@gmail.com>, Hugh Dickins <hughd@google.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] page_alloc: Fix freeing non-compound pages
Date: Tue, 29 Sep 2020 23:53:07 +0100 [thread overview]
Message-ID: <20200929225307.GL20115@casper.infradead.org> (raw)
In-Reply-To: <20200928214656.be4a0f29961589c074e518fa@linux-foundation.org>
On Mon, Sep 28, 2020 at 09:46:56PM -0700, Andrew Morton wrote:
> On Tue, 29 Sep 2020 02:17:19 +0100 Matthew Wilcox <willy@infradead.org> wrote:
>
> > On Mon, Sep 28, 2020 at 06:03:07PM -0700, Andrew Morton wrote:
> > > On Sat, 26 Sep 2020 22:39:19 +0100 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
> > >
> > > > Here is a very rare race which leaks memory:
> > >
> > > Not worth a cc:stable?
> >
> > Yes, it probably should have been.
>
> Have you a feeling for how often this occurs?
I doubt it happens often. I don't think I could construct a workload to
make it happen frequently. Maybe more often with a virtualised workload
where a thread can be preempted between instructions.
> > I just assume the stablebot will
> > pick up anything that has a Fixes: tag.
>
> We asked them not to do that for mm/ patches. Crazy stuff was getting
> backported.
That's a shame. I'll try to remember to cc them explicitly in the future.
> > Although I'm now thinking of making that comment into kernel-doc and
> > turning it into advice to the caller rather than an internal note to
> > other mm developers.
>
> hm. But what action could the caller take? The explanatory comment
> seems OK to me.
Use compound pages instead of non-compound pages. Although Linus has
asked that people stop using __get_free_pages(), so maybe that will be
the direction we go in.
https://lore.kernel.org/lkml/CA+55aFwyxJ+TOpaJZnC5MPJ-25xbLAEu8iJP8zTYhmA3LXFF8Q@mail.gmail.com/
next prev parent reply other threads:[~2020-09-29 22:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-26 21:39 [PATCH v2] page_alloc: Fix freeing non-compound pages Matthew Wilcox (Oracle)
2020-09-29 1:03 ` Andrew Morton
2020-09-29 1:17 ` Matthew Wilcox
2020-09-29 4:46 ` Andrew Morton
2020-09-29 22:53 ` Matthew Wilcox [this message]
2020-10-19 1:00 ` Nicholas Piggin
2020-09-29 3:40 ` Matthew Wilcox
2020-09-29 7:26 ` Mike Rapoport
2020-09-29 14:06 ` Matthew Wilcox
2020-09-30 9:17 ` Mike Rapoport
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