The patch titled
Subject: mm/huge_memory: do not drop the original folio during truncate
has been added to the -mm mm-unstable branch. Its filename is
mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split-fix.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: Zi Yan <ziy@xxxxxxxxxx>
Subject: mm/huge_memory: do not drop the original folio during truncate
Date: Fri, 14 Feb 2025 16:18:24 -0500
The caller expects to handle the original folio itself.
Also make __split_unmapped_folio() never fail, per discussion with David
Hildenbrand.
Link: https://lkml.kernel.org/r/E2B8D781-01EE-4832-8587-4C5FF57F91B3@xxxxxxxxxx
Link: https://lore.kernel.org/all/67af65cb.050a0220.21dd3.004a.GAE@xxxxxxxxxx/
Link: https://lore.kernel.org/linux-mm/db77d017-4a1e-4a47-9064-e335cb0313af@xxxxxxxxxx/
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Kirill A. Shuemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
--- a/mm/huge_memory.c~mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split-fix
+++ a/mm/huge_memory.c
@@ -3386,16 +3386,12 @@ bool can_split_folio(struct folio *folio
* It splits @folio into @new_order folios and copies the @folio metadata to
* all the resulting folios.
*/
-static int __split_folio_to_order(struct folio *folio, int new_order)
+static void __split_folio_to_order(struct folio *folio, int new_order)
{
- int curr_order = folio_order(folio);
long nr_pages = folio_nr_pages(folio);
long new_nr_pages = 1 << new_order;
long index;
- if (curr_order <= new_order)
- return -EINVAL;
-
/*
* Skip the first new_nr_pages, since the new folio from them have all
* the flags from the original folio.
@@ -3490,8 +3486,6 @@ static int __split_folio_to_order(struct
if (!new_order)
ClearPageCompound(&folio->page);
-
- return 0;
}
/*
@@ -3585,7 +3579,6 @@ static int __split_unmapped_folio(struct
int old_order = folio_order(folio);
struct folio *release;
struct folio *end_folio = folio_next(folio);
- int status;
/* order-1 anonymous folio is not supported */
if (folio_test_anon(folio) && split_order == 1)
@@ -3618,12 +3611,7 @@ static int __split_unmapped_folio(struct
split_page_owner(&folio->page, old_order, split_order);
pgalloc_tag_split(folio, old_order, split_order);
- status = __split_folio_to_order(folio, split_order);
-
- if (status < 0) {
- stop_split = true;
- ret = -EINVAL;
- }
+ __split_folio_to_order(folio, split_order);
after_split:
/*
@@ -3661,8 +3649,10 @@ after_split:
folio_test_swapcache(origin_folio)) ?
folio_nr_pages(release) : 0));
- if (release != origin_folio)
- lru_add_page_tail(origin_folio, &release->page,
+ if (release == origin_folio)
+ continue;
+
+ lru_add_page_tail(origin_folio, &release->page,
lruvec, list);
/* Some pages can be beyond EOF: drop them from page cache */
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data.patch
mm-huge_memory-allow-split-shmem-large-folio-to-any-lower-order.patch
selftests-mm-test-splitting-file-backed-thp-to-any-lower-order.patch
xarray-add-xas_try_split-to-split-a-multi-index-entry.patch
xarray-add-xas_try_split-to-split-a-multi-index-entry-fix.patch
mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split.patch
mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split-fix.patch
mm-huge_memory-move-folio-split-common-code-to-__folio_split.patch
mm-huge_memory-add-buddy-allocator-like-non-uniform-folio_split.patch
mm-huge_memory-remove-the-old-unused-__split_huge_page.patch
mm-huge_memory-add-folio_split-to-debugfs-testing-interface.patch
mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation.patch
selftests-mm-add-tests-for-folio_split-buddy-allocator-like-split.patch
mm-filemap-use-xas_try_split-in-__filemap_add_folio.patch
mm-shmem-use-xas_try_split-in-shmem_split_large_entry.patch
