From: Michal Hocko <mhocko@suse.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Minchan Kim <minchan@kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Dan Williams <dan.j.williams@intel.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] swap: Check nrexceptional of swap cache before being freed
Date: Wed, 20 Jan 2021 08:59:46 +0100 [thread overview]
Message-ID: <20210120075946.GD9371@dhcp22.suse.cz> (raw)
In-Reply-To: <87v9bst55v.fsf@yhuang-dev.intel.com>
On Wed 20-01-21 15:54:04, Huang, Ying wrote:
> Michal Hocko <mhocko@suse.com> writes:
>
> > On Wed 20-01-21 15:27:11, Huang Ying wrote:
> >> To catch the error in updating the swap cache shadow entries or their count.
> >
> > What is the error?
>
> There's no error in the current code. But we will change the related
> code in the future. So this checking will help us to prevent error in
> the future. I will change the patch description to make it more clear.
>
> > Can it happens in the real life? Why do we need this
> > patch? Is crashing the kernel the right way to handle the situation?
>
> Emm... The mistake to update swap shadow entries will hurt performance,
> but will not trigger functionality bug. So it may be better to use
> VM_WARN_ON_ONCE().
Yes a warning is much more appropriate approach. The question is whether
a test like this is really necessary. But I will leave that to others to
decide. It was really the bug on that hit my eyes.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-01-20 7:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 7:27 [PATCH] swap: Check nrexceptional of swap cache before being freed Huang Ying
2021-01-20 7:46 ` Michal Hocko
2021-01-20 7:54 ` Huang, Ying
2021-01-20 7:59 ` Michal Hocko [this message]
2021-01-21 18:44 ` Matthew Wilcox
2021-01-22 0:02 ` Huang, Ying
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