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mm: khugepaged: fix the incorrect statistics when collapsing large file folios

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Khugepaged already supports collapsing file large folios (including shmem
mTHP) by commit 7de856ffd0 ("mm: khugepaged: support shmem mTHP
collapse"), and the control parameters in khugepaged:
'khugepaged_max_ptes_swap' and 'khugepaged_max_ptes_none', still compare
based on PTE granularity to determine whether a file collapse is needed. 
However, the statistics for 'present' and 'swap' in
hpage_collapse_scan_file() do not take into account the large folios,
which may lead to incorrect judgments regarding the
khugepaged_max_ptes_swap/none parameters, resulting in unnecessary file
collapses.

To fix this issue, take into account the large folios' statistics for
'present' and 'swap' variables in the hpage_collapse_scan_file().

Link: https://lkml.kernel.org/r/c76305d96d12d030a1a346b50503d148364246d2.1728901391.git.baolin.wang@linux.alibaba.com
Fixes: 7de856ffd0 ("mm: khugepaged: support shmem mTHP collapse")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baolin Wang 2024-10-14 18:24:44 +08:00 committed by Andrew Morton
parent 22ff9b0ff1
commit d60fcaf00d
1 changed files with 2 additions and 2 deletions
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4
mm/khugepaged.c
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@ -2252,7 +2252,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
continue; continue;
if (xa_is_value(folio)) { if (xa_is_value(folio)) {
++swap; swap += 1 << xas_get_order(&xas);
if (cc->is_khugepaged && if (cc->is_khugepaged &&
swap > khugepaged_max_ptes_swap) { swap > khugepaged_max_ptes_swap) {
result = SCAN_EXCEED_SWAP_PTE; result = SCAN_EXCEED_SWAP_PTE;
@ -2299,7 +2299,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
* is just too costly... * is just too costly...
*/ */
present++; present += folio_nr_pages(folio);
if (need_resched()) { if (need_resched()) {
xas_pause(&xas); xas_pause(&xas);