From: Andrew Morton <akpm@linux-foundation.org>
To: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: linux-mm@kvack.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-kernel@vger.kernel.org, Shaohua Li <shli@fusionio.com>,
Minchan Kim <minchan@kernel.org>
Subject: Re: [PATCH] frontswap: enable call to invalidate area on swapoff
Date: Tue, 8 Oct 2013 13:08:53 -0700 [thread overview]
Message-ID: <20131008130853.96139b79a0a4d3aaacc79ed2@linux-foundation.org> (raw)
In-Reply-To: <1381220000.16135.10.camel@AMDC1943>
On Tue, 08 Oct 2013 10:13:20 +0200 Krzysztof Kozlowski <k.kozlowski@samsung.com> wrote:
> On pon, 2013-10-07 at 15:03 -0700, Andrew Morton wrote:
> > On Mon, 07 Oct 2013 17:25:41 +0200 Krzysztof Kozlowski <k.kozlowski@samsung.com> wrote:
> >
> > > During swapoff the frontswap_map was NULL-ified before calling
> > > frontswap_invalidate_area(). However the frontswap_invalidate_area()
> > > exits early if frontswap_map is NULL. Invalidate was never called during
> > > swapoff.
> > >
> > > This patch moves frontswap_map_set() in swapoff just after calling
> > > frontswap_invalidate_area() so outside of locks
> > > (swap_lock and swap_info_struct->lock). This shouldn't be a problem as
> > > during swapon the frontswap_map_set() is called also outside of any
> > > locks.
> > >
> >
> > Ahem. So there's a bunch of code in __frontswap_invalidate_area()
> > which hasn't ever been executed and nobody noticed it. So perhaps that
> > code isn't actually needed?
> >
> > More seriously, this patch looks like it enables code which hasn't been
> > used or tested before. How well tested was this?
> >
> > Are there any runtime-visible effects from this change?
>
> I tested zswap on x86 and x86-64 and there was no difference. This is
> good as there shouldn't be visible anything because swapoff is unusing
> all pages anyway:
> try_to_unuse(type, false, 0); /* force all pages to be unused */
>
> I haven't tested other frontswap users.
So is that code in __frontswap_invalidate_area() unneeded?
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next prev parent reply other threads:[~2013-10-08 20:08 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-07 15:25 Krzysztof Kozlowski
2013-10-07 15:37 ` Seth Jennings
2013-10-07 22:03 ` Andrew Morton
2013-10-08 8:13 ` Krzysztof Kozlowski
2013-10-08 20:08 ` Andrew Morton [this message]
2013-10-09 7:50 ` Bob Liu
2013-10-09 14:40 ` Seth Jennings
2013-10-10 1:29 ` Bob Liu
2013-10-10 2:26 ` Seth Jennings
2013-10-11 2:23 ` Weijie Yang
2013-10-11 9:25 ` Krzysztof Kozlowski
2013-10-11 9:42 ` Weijie Yang
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