* Re: 3.18-rc3: soft lockup in compact_zone, dead machine
[not found] <20141107100611.GA4175@amd>
@ 2014-11-07 16:54 ` Vlastimil Babka
0 siblings, 0 replies; only message in thread
From: Vlastimil Babka @ 2014-11-07 16:54 UTC (permalink / raw)
To: Pavel Machek, kernel list
Cc: Andrew Morton, David Rientjes, linux-mm, Joonsoo Kim
On 11/07/2014 11:06 AM, Pavel Machek wrote:
> Hi!
>
> My main machine died completely, it seems that original failure was
> soft lockup in compact_zone().
(expanding CC)
Welcome to the club...
http://article.gmane.org/gmane.linux.kernel.mm/124451/match=isolate_freepages_block+very+high+intermittent+overhead
https://lkml.org/lkml/2014/11/4/144
https://lkml.org/lkml/2014/11/4/904
How reproducible is your case? So far it seems that git revert
e14c720efdd73c6d69cd8d07fa894bcd11fe1973 helped one of the reporters.
I still don't know what's wrong, but suspect a free scanner
(cc->free_pfn) position being broken (i.e. underflow), which would allow
isolate_migratepages() to run for a loooooooong time. The code does
cond_resched() periodically, so soft lockup looks strange, but I guess
that can happen in some contexts?
Vlastimil
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[not found] <20141107100611.GA4175@amd>
2014-11-07 16:54 ` 3.18-rc3: soft lockup in compact_zone, dead machine Vlastimil Babka
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