From: David Hildenbrand <david@redhat.com>
To: Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
akpm@linux-foundation.org, willy@infradead.org
Cc: anshuman.khandual@arm.com, catalin.marinas@arm.com,
cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com,
apopple@nvidia.com, osalvador@suse.de,
baolin.wang@linux.alibaba.com, dave.hansen@linux.intel.com,
will@kernel.org, baohua@kernel.org, ioworker0@gmail.com,
gshan@redhat.com, mark.rutland@arm.com,
kirill.shutemov@linux.intel.com, hughd@google.com,
aneesh.kumar@kernel.org, yang@os.amperecomputing.com,
peterx@redhat.com, broonie@kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Race condition observed between page migration and page fault handling on arm64 machines
Date: Thu, 1 Aug 2024 15:15:31 +0200 [thread overview]
Message-ID: <3636af63-8865-4ef5-a2f3-2a6538aca873@redhat.com> (raw)
In-Reply-To: <738342dc-4a87-4dcc-a515-a9dc085e3186@arm.com>
>> What I am still missing is why this is (a) arm64 only; and (b) if this is
>> something we should really worry about. There are other reasons (e.g.,
>> speculative references) why migration could temporarily fail, does it happen
>> that often that it is really something we have to worry about?
>
> The test fails consistently on arm64. It's my rough understanding that it's
> failing due to migration backing off because the fault handler has raised the
> ref count? (Dev correct me if I'm wrong).
>
> So the real question is, is it a valid test in the first place? Should we just
> delete the test or do we need to strengthen the kernel's guarrantees around
> migration success?
I think the test should retry migration a number of times in case it
fails. But if it is a persistent migration failure, the test should fail.
--
Cheers,
David / dhildenb
prev parent reply other threads:[~2024-08-01 13:15 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-01 8:16 Race condition observed between page migration and page fault handling on arm64 machines Dev Jain
2024-08-01 8:42 ` David Hildenbrand
2024-08-01 9:38 ` Dev Jain
2024-08-01 9:41 ` David Hildenbrand
2024-08-01 10:05 ` Dev Jain
2024-08-01 13:13 ` David Hildenbrand
2024-08-01 13:26 ` David Hildenbrand
2024-08-01 13:43 ` Will Deacon
2024-08-01 13:48 ` David Hildenbrand
2024-08-01 14:25 ` Ryan Roberts
2024-08-05 9:51 ` Dev Jain
2024-08-05 10:46 ` David Hildenbrand
2024-08-05 14:14 ` Dev Jain
[not found] ` <a8c813b5-abce-48cf-9d14-2f969d6c8180@redhat.com>
[not found] ` <8158c9d6-cbfe-4767-be8e-dc227b29200c@arm.com>
2024-08-09 13:23 ` David Hildenbrand
2024-08-09 13:26 ` David Hildenbrand
2024-08-01 10:06 ` Ryan Roberts
2024-08-01 13:15 ` David Hildenbrand [this message]
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