The patch titled
Subject: mm: migrate: split folio_migrate_mapping()
has been added to the -mm mm-unstable branch. Its filename is
mm-migrate-split-folio_migrate_mapping.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-migrate-split-folio_migrate_mapping.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Subject: mm: migrate: split folio_migrate_mapping()
Date: Mon, 3 Jun 2024 17:24:36 +0800
The folio refcount check for !mapping and folio_ref_freeze() for mapping
are moved out of the original folio_migrate_mapping(), and there is no
turning back for the new __folio_migrate_mapping(), also update comment
from page to folio.
Note, the folio_ref_freeze() is moved out of xas_lock_irq(), Since the
folio is already isolated and locked during migration, so suppose that
there is no functional change.
Link: https://lkml.kernel.org/r/20240603092439.3360652-4-wangkefeng.wang@xxxxxxxxxx
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Benjamin LaHaise <bcrl@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jane Chu <jane.chu@xxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Jiaqi Yan <jiaqiyan@xxxxxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 63 ++++++++++++++++++++++++-------------------------
1 file changed, 32 insertions(+), 31 deletions(-)
--- a/mm/migrate.c~mm-migrate-split-folio_migrate_mapping
+++ a/mm/migrate.c
@@ -393,50 +393,36 @@ static int folio_expected_refs(struct ad
}
/*
- * Replace the page in the mapping.
+ * Replace the folio in the mapping.
*
* The number of remaining references must be:
- * 1 for anonymous pages without a mapping
- * 2 for pages with a mapping
- * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
+ * 1 for anonymous folios without a mapping
+ * 2 for folios with a mapping
+ * 3 for folios with a mapping and PagePrivate/PagePrivate2 set.
*/
-int folio_migrate_mapping(struct address_space *mapping,
- struct folio *newfolio, struct folio *folio, int extra_count)
+static void __folio_migrate_mapping(struct address_space *mapping,
+ struct folio *newfolio, struct folio *folio, int expected_cnt)
{
XA_STATE(xas, &mapping->i_pages, folio_index(folio));
struct zone *oldzone, *newzone;
- int dirty;
- int expected_count = folio_expected_refs(mapping, folio) + extra_count;
long nr = folio_nr_pages(folio);
long entries, i;
+ int dirty;
if (!mapping) {
- /* Anonymous page without mapping */
- if (folio_ref_count(folio) != expected_count)
- return -EAGAIN;
-
- /* No turning back from here */
+ /* Anonymous folio without mapping */
newfolio->index = folio->index;
newfolio->mapping = folio->mapping;
if (folio_test_swapbacked(folio))
__folio_set_swapbacked(newfolio);
-
- return MIGRATEPAGE_SUCCESS;
+ return;
}
oldzone = folio_zone(folio);
newzone = folio_zone(newfolio);
xas_lock_irq(&xas);
- if (!folio_ref_freeze(folio, expected_count)) {
- xas_unlock_irq(&xas);
- return -EAGAIN;
- }
-
- /*
- * Now we know that no one else is looking at the folio:
- * no turning back from here.
- */
+ /* Now we know that no one else is looking at the folio */
newfolio->index = folio->index;
newfolio->mapping = folio->mapping;
folio_ref_add(newfolio, nr); /* add cache reference */
@@ -452,7 +438,7 @@ int folio_migrate_mapping(struct address
entries = 1;
}
- /* Move dirty while page refs frozen and newpage not yet exposed */
+ /* Move dirty while folio refs frozen and newfolio not yet exposed */
dirty = folio_test_dirty(folio);
if (dirty) {
folio_clear_dirty(folio);
@@ -466,22 +452,22 @@ int folio_migrate_mapping(struct address
}
/*
- * Drop cache reference from old page by unfreezing
- * to one less reference.
+ * Since old folio's refcount freezed, now drop cache reference from
+ * old folio by unfreezing to one less reference.
* We know this isn't the last reference.
*/
- folio_ref_unfreeze(folio, expected_count - nr);
+ folio_ref_unfreeze(folio, expected_cnt - nr);
xas_unlock(&xas);
/* Leave irq disabled to prevent preemption while updating stats */
/*
* If moved to a different zone then also account
- * the page for that zone. Other VM counters will be
+ * the folio for that zone. Other VM counters will be
* taken care of when we establish references to the
- * new page and drop references to the old page.
+ * new folio and drop references to the old folio.
*
- * Note that anonymous pages are accounted for
+ * Note that anonymous folios are accounted for
* via NR_FILE_PAGES and NR_ANON_MAPPED if they
* are mapped to swap space.
*/
@@ -518,7 +504,22 @@ int folio_migrate_mapping(struct address
}
}
local_irq_enable();
+}
+
+int folio_migrate_mapping(struct address_space *mapping, struct folio *newfolio,
+ struct folio *folio, int extra_count)
+{
+ int expected_cnt = folio_expected_refs(mapping, folio) + extra_count;
+
+ if (!mapping) {
+ if (folio_ref_count(folio) != expected_cnt)
+ return -EAGAIN;
+ } else {
+ if (!folio_ref_freeze(folio, expected_cnt))
+ return -EAGAIN;
+ }
+ __folio_migrate_mapping(mapping, newfolio, folio, expected_cnt);
return MIGRATEPAGE_SUCCESS;
}
EXPORT_SYMBOL(folio_migrate_mapping);
_
Patches currently in -mm which might be from wangkefeng.wang@xxxxxxxxxx are
mm-add-folio_alloc_mpol.patch
mm-mempolicy-use-folio_alloc_mpol_noprof-in-vma_alloc_folio_noprof.patch
mm-mempolicy-use-folio_alloc_mpol-in-alloc_migration_target_by_mpol.patch
mm-shmem-use-folio_alloc_mpol-in-shmem_alloc_folio.patch
mm-refactor-folio_undo_large_rmappable.patch
mm-memcontrol-remove-page_memcg.patch
rmap-remove-define_page_vma_walk.patch
mm-migrate-simplify-__buffer_migrate_folio.patch
mm-migrate_device-use-a-newfolio-in-__migrate_device_pages.patch
mm-migrate_device-unify-migrate-folio-for-migrate_sync_no_copy.patch
mm-migrate-remove-migrate_folio_extra.patch
mm-remove-migrate_sync_no_copy-mode.patch
fs-proc-task_mmu-use-folio-api-in-pte_is_pinned.patch
mm-remove-page_maybe_dma_pinned.patch
fb_defio-use-a-folio-in-fb_deferred_io_work.patch
mm-remove-page_mkclean.patch
mm-move-memory_failure_queue-into-copy_mc__highpage.patch
mm-add-folio_mc_copy.patch
mm-migrate-split-folio_migrate_mapping.patch
mm-migrate-support-poisoned-recover-from-migrate-folio.patch
fs-hugetlbfs-support-poison-recover-from-hugetlbfs_migrate_folio.patch
mm-migrate-remove-folio_migrate_copy.patch
