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From: Aristeu Rozanski <aris@ruivo.org>
To: kernel test robot <oliver.sang@intel.com>
Cc: Aristeu Rozanski <aris@redhat.com>,
	oe-lkp@lists.linux.dev, lkp@intel.com,
	Linux Memory Management List <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Muchun Song <muchun.song@linux.dev>,
	David Hildenbrand <david@redhat.com>,
	Vishal Moola <vishal.moola@gmail.com>
Subject: Re: [linux-next:master] [hugetlb]  003af997c8: libhugetlbfs-test.32/64bit.counters_sh.fail
Date: Wed, 17 Jul 2024 16:45:07 -0400	[thread overview]
Message-ID: <20240717204507.GJ844599@cathedrallabs.org> (raw)
In-Reply-To: <20240716154427.GI844599@cathedrallabs.org>

On Tue, Jul 16, 2024 at 11:44:27AM -0400, Aristeu Rozanski wrote:
> Taking a look on this.

So it looks like to be a timing issue. While spreading some code to figure out
exactly which exact sequence is causing the issue, it makes the error go away
in the 'counters' test. More specifically one of the sequences:

        /* touched, shared mmap */
	map(SL_TEST, 1, MAP_SHARED);
	touch(SL_TEST, 1, MAP_SHARED);
	unmap(SL_TEST, 1, MAP_SHARED);

fails because it's expecting:

	HugePages_{Total,Free} = 1
	HugePages_Surp = 0

but gets:

	HugePages_{Total,Free} = 2
	HugePages_Surp = 1

which seems caused by a surplus page taking too long to be freed, thus
timing making difference here.

I'm not sure as why it'd take longer with my patch applied but will keep
digging.

-- 
Aristeu



  reply	other threads:[~2024-07-17 20:45 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-16 13:30 kernel test robot
2024-07-16 15:44 ` Aristeu Rozanski
2024-07-17 20:45   ` Aristeu Rozanski [this message]
2024-07-24 19:48     ` Aristeu Rozanski

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