From: "Christoph Lameter (Ampere)" <cl@gentwo.org>
To: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>,
akpm@linux-foundation.org, shuah@kernel.org,
willy@infradead.org, ryan.roberts@arm.com,
anshuman.khandual@arm.com, catalin.marinas@arm.com,
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,
mgorman@techsingularity.net,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: Retry migration earlier upon refcount mismatch
Date: Fri, 9 Aug 2024 14:09:10 -0700 (PDT) [thread overview]
Message-ID: <43db36cb-339c-4aa8-8940-1a197bd1001d@gentwo.org> (raw)
In-Reply-To: <761ba58e-9d6f-4a14-a513-dcc098c2aa94@redhat.com>
On Fri, 9 Aug 2024, David Hildenbrand wrote:
>
> This really seems to be the latest point where we can "easily" back off and
> unlock the source folio -- in this function :)
>
> I wonder if we should be smarter in the migrate_pages_batch() loop when we
> start the actual migrations via migrate_folio_move(): if we detect that a
> folio has unexpected references *and* it has waiters (PG_waiters), back off
> then and retry the folio later. If it only has unexpected references, just
> keep retrying: no waiters -> nobody is waiting for the lock to make progress.
Well just backoff ASAP if there are waiters detected anytime. A waiter
would have increased the refcount. And a waiter will likely modify the page status soon. So
push it to the end of the pages to be migrated to give it as much time
as we can and check again later.
next prev parent reply other threads:[~2024-08-10 0:13 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-09 10:31 [PATCH 0/2] Improve migration by backing off earlier Dev Jain
2024-08-09 10:31 ` [PATCH 1/2] mm: Retry migration earlier upon refcount mismatch Dev Jain
2024-08-09 13:47 ` David Hildenbrand
2024-08-09 21:09 ` Christoph Lameter (Ampere) [this message]
2024-08-10 18:42 ` Dev Jain
2024-08-10 18:52 ` David Hildenbrand
2024-08-11 6:06 ` Dev Jain
2024-08-11 9:08 ` David Hildenbrand
2024-08-12 5:35 ` Dev Jain
2024-08-12 9:30 ` David Hildenbrand
2024-08-10 21:05 ` Zi Yan
2024-08-12 5:34 ` Huang, Ying
2024-08-12 6:01 ` Dev Jain
2024-08-12 6:15 ` Huang, Ying
2024-08-12 6:52 ` Dev Jain
2024-08-12 7:31 ` Huang, Ying
2024-08-12 12:08 ` Dev Jain
2024-08-13 5:00 ` Dev Jain
2024-08-13 7:22 ` Dev Jain
2024-08-16 11:31 ` Dev Jain
2024-08-19 6:58 ` Huang, Ying
2024-08-20 7:16 ` Dev Jain
2024-09-02 6:42 ` Huang, Ying
2024-08-12 6:13 ` Dev Jain
2024-08-12 6:20 ` Huang, Ying
2024-08-12 6:32 ` Dev Jain
2024-08-09 10:31 ` [PATCH 2/2] selftests/mm: Do not fail test for a single migration failure Dev Jain
2024-08-09 17:13 ` Shuah Khan
2024-08-09 21:10 ` Christoph Lameter (Ampere)
2024-08-12 6:19 ` Dev Jain
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