diff options
| author | Kairui Song <kasong@tencent.com> | 2025-09-17 00:00:55 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-09-21 14:22:24 -0700 |
| commit | 094dc8b059b11eef0888f43eeb0f3ac53ade5c87 (patch) | |
| tree | af3c689e3d27e170e4cc208cc82188132e246f12 /mm/migrate.c | |
| parent | mm/shmem, swap: remove redundant error handling for replacing folio (diff) | |
| download | linux-094dc8b059b11eef0888f43eeb0f3ac53ade5c87.tar.gz linux-094dc8b059b11eef0888f43eeb0f3ac53ade5c87.zip | |
mm, swap: wrap swap cache replacement with a helper
There are currently three swap cache users that are trying to replace an
existing folio with a new one: huge memory splitting, migration, and shmem
replacement. What they are doing is quite similar.
Introduce a common helper for this. In later commits, this can be easily
switched to use the swap table by updating this helper.
The newly added helper also makes the swap cache API better defined, and
make debugging easier by adding a few more debug checks.
Migration and shmem replace are meant to clone the folio, including
content, swap entry value, and flags. And splitting will adjust each sub
folio's swap entry according to order, which could be non-uniform in the
future. So document it clearly that it's the caller's responsibility to
set up the new folio's swap entries and flags before calling the helper.
The helper will just follow the new folio's entry value.
This also prepares for replacing high-order folios in the swap cache.
Currently, only splitting to order 0 is allowed for swap cache folios.
Using the new helper, we can handle high-order folio splitting better.
Link: https://lkml.kernel.org/r/20250916160100.31545-11-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Chris Li <chrisl@kernel.org>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 8e435a078fc3..c69cc13db692 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -566,7 +566,6 @@ static int __folio_migrate_mapping(struct address_space *mapping, struct zone *oldzone, *newzone; int dirty; long nr = folio_nr_pages(folio); - long entries, i; if (!mapping) { /* Take off deferred split queue while frozen and memcg set */ @@ -615,9 +614,6 @@ static int __folio_migrate_mapping(struct address_space *mapping, if (folio_test_swapcache(folio)) { folio_set_swapcache(newfolio); newfolio->private = folio_get_private(folio); - entries = nr; - } else { - entries = 1; } /* Move dirty while folio refs frozen and newfolio not yet exposed */ @@ -627,11 +623,10 @@ static int __folio_migrate_mapping(struct address_space *mapping, folio_set_dirty(newfolio); } - /* Swap cache still stores N entries instead of a high-order entry */ - for (i = 0; i < entries; i++) { + if (folio_test_swapcache(folio)) + __swap_cache_replace_folio(folio, newfolio); + else xas_store(&xas, newfolio); - xas_next(&xas); - } /* * Drop cache reference from old folio by unfreezing |