From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Alistair Popple <apopple@nvidia.com>, John Hubbard <jhubbard@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Zi Yan <ziy@nvidia.com>,
Matthew Brost <matthew.brost@intel.com>,
Joshua Hahn <joshua.hahnjy@gmail.com>,
Rakie Kim <rakie.kim@sk.com>, Byungchul Park <byungchul@sk.com>,
Gregory Price <gourry@gourry.net>,
Ying Huang <ying.huang@linux.alibaba.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
Chris Li <chrisl@kernel.org>, Kairui Song <kasong@tencent.com>,
Kemeng Shi <shikemeng@huaweicloud.com>,
Nhat Pham <nphamcs@gmail.com>, Baoquan He <bhe@redhat.com>,
Barry Song <baohua@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [RFC PATCH 2/2] mm/migrate: wait for folio refcount during longterm pin migration
Date: Thu, 23 Apr 2026 15:22:11 +0200 [thread overview]
Message-ID: <b9f5622a-5806-4b22-8b9c-5d968a14a792@kernel.org> (raw)
In-Reply-To: <aecQkNxjoMReR6Ss@nvdebian.thelocal>
On 4/21/26 07:57, Alistair Popple wrote:
> On 2026-04-10 at 13:23 +1000, John Hubbard <jhubbard@nvidia.com> wrote...
>> When migrating pages for FOLL_LONGTERM pinning (MR_LONGTERM_PIN), the
>> migration can fail with -EAGAIN if the folio has unexpected references.
>> These references are often transient (e.g., from GPU operations like
>> cuMemset that will complete shortly).
>
> Is there a reason this logic should only apply to FOLL_LONGTERM pinning?
> Or could it also apply more generally to any ZONE_MOVABLE page, for which
> migration should eventually succeed? Currently that has similar retry logic of
> NR_MAX_MIGRATE_PAGES_RETRY times and give up.
>
> We have a similar retry problems in mm/migrate_device.c:migrate_vma_*() so I
> could see something similar being potentially useful there.
Agreed on both!
--
Cheers,
David
next prev parent reply other threads:[~2026-04-23 13:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-10 3:23 [RFC PATCH 0/2] mm/migrate: wait for folio refcount during longterm pin migration John Hubbard
2026-04-10 3:23 ` [RFC PATCH 1/2] mm: wake up folio refcount waiters on folio_put() John Hubbard
2026-04-10 3:23 ` [RFC PATCH 2/2] mm/migrate: wait for folio refcount during longterm pin migration John Hubbard
2026-04-21 5:57 ` Alistair Popple
2026-04-23 13:22 ` David Hildenbrand (Arm) [this message]
2026-04-21 9:21 ` Huang, Ying
2026-04-21 5:52 ` [RFC PATCH 0/2] " Alistair Popple
2026-04-21 9:19 ` Huang, Ying
2026-04-21 16:00 ` David Hildenbrand (Arm)
2026-04-22 1:46 ` Huang, Ying
2026-04-23 2:52 ` John Hubbard
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