From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Florian Weimer <fw@deneb.enyo.de>,
Dave Chinner <david@fromorbit.com>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [bug, 5.2.16] kswapd/compaction null pointer crash [was Re: xfs_inode not reclaimed/memory leak on 5.2.16]
Date: Tue, 8 Oct 2019 09:52:19 +0100 [thread overview]
Message-ID: <20191008085219.GC3321@techsingularity.net> (raw)
In-Reply-To: <1f0f2849-d90e-6563-0034-07ba80f8ba2f@suse.cz>
On Mon, Oct 07, 2019 at 03:56:41PM +0200, Vlastimil Babka wrote:
> On 10/7/19 3:28 PM, Vlastimil Babka wrote:
> > On 10/1/19 9:40 PM, Florian Weimer wrote:
> >> * Vlastimil Babka:
> >>
> >>
> >> See below. I don't have debuginfo for this build, and the binary does
> >> not reproduce for some reason. Due to the heavy inlining, it might be
> >> quite hard to figure out what's going on.
> >
> > Thanks, but I'm still not able to "decompile" that in my head.
>
> While staring at the code, I think I found two probably unrelated bugs.
> One is that pfn and page might be desynced when zone starts in the middle
> of pageblock, as the max() is only applied to page and not pfn. But that
> only effectively affects the later pfn_valid_within() checks, which should
> be always true on x86.
>
> The second is that "end of pageblock online and valid" should refer to
> the last pfn of pageblock, not first pfn of next pageblocks. Otherwise we
> might return false needlessly. Mel, what do you think?
>
I think you are correct in both cases. It's perfectly possible I would
not have observed a problem in testing if zones were aligned which I
think is generally the case on my test machines.
--
Mel Gorman
SUSE Labs
prev parent reply other threads:[~2019-10-08 9:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-30 7:28 xfs_inode not reclaimed/memory leak on 5.2.16 Florian Weimer
2019-09-30 8:54 ` Dave Chinner
2019-09-30 19:07 ` Florian Weimer
2019-09-30 21:17 ` [bug, 5.2.16] kswapd/compaction null pointer crash [was Re: xfs_inode not reclaimed/memory leak on 5.2.16] Dave Chinner
2019-09-30 21:42 ` Florian Weimer
2019-10-01 9:10 ` Vlastimil Babka
2019-10-01 19:40 ` Florian Weimer
2019-10-07 13:28 ` Vlastimil Babka
2019-10-07 13:56 ` Vlastimil Babka
2019-10-08 8:52 ` Mel Gorman [this message]
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