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Message-ID: <3bb725f8-28d7-4aa2-b75f-af40d5cab280@redhat.com>
Date: Mon, 18 Aug 2025 13:28:22 +0200
From: David Hildenbrand <david@...hat.com>
To: Lance Yang <lance.yang@...ux.dev>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linuxppc-dev@...ts.ozlabs.org, virtualization@...ts.linux.dev,
linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
linux-btrfs@...r.kernel.org, jfs-discussion@...ts.sourceforge.net,
Andrew Morton <akpm@...ux-foundation.org>,
Madhavan Srinivasan <maddy@...ux.ibm.com>,
Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Jerrin Shaji George <jerrin.shaji-george@...adcom.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez
<eperezma@...hat.com>, Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
Benjamin LaHaise <bcrl@...ck.org>, Chris Mason <clm@...com>,
Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>,
Muchun Song <muchun.song@...ux.dev>, Oscar Salvador <osalvador@...e.de>,
Dave Kleikamp <shaggy@...nel.org>, Zi Yan <ziy@...dia.com>,
Matthew Brost <matthew.brost@...el.com>,
Joshua Hahn <joshua.hahnjy@...il.com>, Rakie Kim <rakie.kim@...com>,
Byungchul Park <byungchul@...com>, Gregory Price <gourry@...rry.net>,
Ying Huang <ying.huang@...ux.alibaba.com>,
Alistair Popple <apopple@...dia.com>, Minchan Kim <minchan@...nel.org>,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH v1 1/2] mm/migrate: remove MIGRATEPAGE_UNMAP
On 13.08.25 07:05, Lance Yang wrote:
> On Mon, Aug 11, 2025 at 10:47 PM David Hildenbrand <david@...hat.com> wrote:
>>
> [...]
>> +++ b/mm/migrate.c
>> @@ -1176,16 +1176,6 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>> bool locked = false;
>> bool dst_locked = false;
>>
>> - if (folio_ref_count(src) == 1) {
>> - /* Folio was freed from under us. So we are done. */
>> - folio_clear_active(src);
>> - folio_clear_unevictable(src);
>> - /* free_pages_prepare() will clear PG_isolated. */
>> - list_del(&src->lru);
>> - migrate_folio_done(src, reason);
>> - return MIGRATEPAGE_SUCCESS;
>> - }
>> -
>> dst = get_new_folio(src, private);
>> if (!dst)
>> return -ENOMEM;
>> @@ -1275,7 +1265,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>>
>> if (unlikely(page_has_movable_ops(&src->page))) {
>> __migrate_folio_record(dst, old_page_state, anon_vma);
>> - return MIGRATEPAGE_UNMAP;
>> + return 0;
>> }
>>
>> /*
>> @@ -1305,7 +1295,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>>
>> if (!folio_mapped(src)) {
>> __migrate_folio_record(dst, old_page_state, anon_vma);
>> - return MIGRATEPAGE_UNMAP;
>> + return 0;
>> }
>>
>> out:
>> @@ -1848,14 +1838,28 @@ static int migrate_pages_batch(struct list_head *from,
>> continue;
>> }
>>
>> + /*
>> + * If we are holding the last folio reference, the folio
>> + * was freed from under us, so just drop our reference.
>> + */
>> + if (likely(!page_has_movable_ops(&folio->page)) &&
>> + folio_ref_count(folio) == 1) {
>> + folio_clear_active(folio);
>> + folio_clear_unevictable(folio);
>> + list_del(&folio->lru);
>> + migrate_folio_done(folio, reason);
>> + stats->nr_succeeded += nr_pages;
>> + stats->nr_thp_succeeded += is_thp;
>> + continue;
>> + }
>> +
>
> It seems the reason parameter is no longer used within migrate_folio_unmap()
> after this patch.
>
> Perhaps it could be removed from the function's signature ;)
Thanks, well spotted, @Andrew can you squash the following?
From 40938bb0de20e03250c813d5abc7286aea69d835 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <david@...hat.com>
Date: Mon, 18 Aug 2025 13:26:05 +0200
Subject: [PATCH] fixup: mm/migrate: remove MIGRATEPAGE_UNMAP
No need to pass "reason" to migrate_folio_unmap().
Signed-off-by: David Hildenbrand <david@...hat.com>
---
mm/migrate.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 2db4974178e6a..aabc736eec022 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1166,7 +1166,7 @@ static void migrate_folio_done(struct folio *src,
static int migrate_folio_unmap(new_folio_t get_new_folio,
free_folio_t put_new_folio, unsigned long private,
struct folio *src, struct folio **dstp, enum migrate_mode mode,
- enum migrate_reason reason, struct list_head *ret)
+ struct list_head *ret)
{
struct folio *dst;
int rc = -EAGAIN;
@@ -1852,8 +1852,7 @@ static int migrate_pages_batch(struct list_head *from,
}
rc = migrate_folio_unmap(get_new_folio, put_new_folio,
- private, folio, &dst, mode, reason,
- ret_folios);
+ private, folio, &dst, mode, ret_folios);
/*
* The rules are:
* 0: folio will be put on unmap_folios list,
--
2.50.1
--
Cheers
David / dhildenb
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