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mm: khugepaged: support shmem mTHP collapse

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Shmem already supports the allocation of mTHP, but khugepaged does not yet
support collapsing mTHP folios.  Now khugepaged is ready to support mTHP,
and this patch enables the collapse of shmem mTHP.

Link: https://lkml.kernel.org/r/b9da76aab4276eb6e5d12c479af2b5eea5b4575d.1724140601.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baolin Wang 2024-08-20 17:49:16 +08:00 committed by Andrew Morton
parent dfa98f56d9
commit 7de856ffd0
1 changed files with 11 additions and 17 deletions
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28
mm/khugepaged.c
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@ -1843,7 +1843,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
}
} while (1);
for (index = start; index < end; index++) {
for (index = start; index < end;) {
xas_set(&xas, index);
folio = xas_load(&xas);
@ -1862,6 +1862,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
}
}
nr_none++;
index++;
continue;
}
@ -1943,12 +1944,10 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
* we locked the first folio, then a THP might be there already.
* This will be discovered on the first iteration.
*/
if (folio_test_large(folio)) {
result = folio_order(folio) == HPAGE_PMD_ORDER &&
folio->index == start
/* Maybe PMD-mapped */
? SCAN_PTE_MAPPED_HUGEPAGE
: SCAN_PAGE_COMPOUND;
if (folio_order(folio) == HPAGE_PMD_ORDER &&
folio->index == start) {
/* Maybe PMD-mapped */
result = SCAN_PTE_MAPPED_HUGEPAGE;
goto out_unlock;
}
@ -2009,6 +2008,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
* Accumulate the folios that are being collapsed.
*/
list_add_tail(&folio->lru, &pagelist);
index += folio_nr_pages(folio);
continue;
out_unlock:
folio_unlock(folio);
@ -2261,16 +2261,10 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
continue;
}
/*
* TODO: khugepaged should compact smaller compound pages
* into a PMD sized page
*/
if (folio_test_large(folio)) {
result = folio_order(folio) == HPAGE_PMD_ORDER &&
folio->index == start
/* Maybe PMD-mapped */
? SCAN_PTE_MAPPED_HUGEPAGE
: SCAN_PAGE_COMPOUND;
if (folio_order(folio) == HPAGE_PMD_ORDER &&
folio->index == start) {
/* Maybe PMD-mapped */
result = SCAN_PTE_MAPPED_HUGEPAGE;
/*
* For SCAN_PTE_MAPPED_HUGEPAGE, further processing
* by the caller won't touch the page cache, and so