The patch titled
Subject: mm/khugepaged: convert hpage_collapse_scan_pmd() to use folios
has been added to the -mm mm-unstable branch. Its filename is
mm-khugepaged-convert-hpage_collapse_scan_pmd-to-use-folios.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-convert-hpage_collapse_scan_pmd-to-use-folios.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: "Vishal Moola (Oracle)" <vishal.moola@xxxxxxxxx>
Subject: mm/khugepaged: convert hpage_collapse_scan_pmd() to use folios
Date: Mon, 16 Oct 2023 13:05:07 -0700
Replaces 5 calls to compound_head(), and removes 1466 bytes of kernel
text.
Previously, to determine if any pte was shared, the page mapcount
corresponding exactly to the pte was checked. This gave us a precise
number of shared ptes. Using folio_estimated_sharers() instead uses the
mapcount of the head page, giving us an estimate for tail page ptes.
This means if a tail page's mapcount is greater than its head page's
mapcount, folio_estimated_sharers() would be underestimating the number of
shared ptes, and vice versa.
Link: https://lkml.kernel.org/r/20231016200510.7387-3-vishal.moola@xxxxxxxxx
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)
--- a/mm/khugepaged.c~mm-khugepaged-convert-hpage_collapse_scan_pmd-to-use-folios
+++ a/mm/khugepaged.c
@@ -1245,7 +1245,7 @@ static int hpage_collapse_scan_pmd(struc
pte_t *pte, *_pte;
int result = SCAN_FAIL, referenced = 0;
int none_or_zero = 0, shared = 0;
- struct page *page = NULL;
+ struct folio *folio = NULL;
unsigned long _address;
spinlock_t *ptl;
int node = NUMA_NO_NODE, unmapped = 0;
@@ -1316,13 +1316,13 @@ static int hpage_collapse_scan_pmd(struc
if (pte_write(pteval))
writable = true;
- page = vm_normal_page(vma, _address, pteval);
- if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
+ folio = vm_normal_folio(vma, _address, pteval);
+ if (unlikely(!folio) || unlikely(folio_is_zone_device(folio))) {
result = SCAN_PAGE_NULL;
goto out_unmap;
}
- if (page_mapcount(page) > 1) {
+ if (folio_estimated_sharers(folio) > 1) {
++shared;
if (cc->is_khugepaged &&
shared > khugepaged_max_ptes_shared) {
@@ -1332,29 +1332,27 @@ static int hpage_collapse_scan_pmd(struc
}
}
- page = compound_head(page);
-
/*
* Record which node the original page is from and save this
* information to cc->node_load[].
* Khugepaged will allocate hugepage from the node has the max
* hit record.
*/
- node = page_to_nid(page);
+ node = folio_nid(folio);
if (hpage_collapse_scan_abort(node, cc)) {
result = SCAN_SCAN_ABORT;
goto out_unmap;
}
cc->node_load[node]++;
- if (!PageLRU(page)) {
+ if (!folio_test_lru(folio)) {
result = SCAN_PAGE_LRU;
goto out_unmap;
}
- if (PageLocked(page)) {
+ if (folio_test_locked(folio)) {
result = SCAN_PAGE_LOCK;
goto out_unmap;
}
- if (!PageAnon(page)) {
+ if (!folio_test_anon(folio)) {
result = SCAN_PAGE_ANON;
goto out_unmap;
}
@@ -1369,7 +1367,7 @@ static int hpage_collapse_scan_pmd(struc
* has excessive GUP pins (i.e. 512). Anyway the same check
* will be done again later the risk seems low.
*/
- if (!is_refcount_suitable(page)) {
+ if (!is_refcount_suitable(&folio->page)) {
result = SCAN_PAGE_COUNT;
goto out_unmap;
}
@@ -1379,8 +1377,8 @@ static int hpage_collapse_scan_pmd(struc
* enough young pte to justify collapsing the page
*/
if (cc->is_khugepaged &&
- (pte_young(pteval) || page_is_young(page) ||
- PageReferenced(page) || mmu_notifier_test_young(vma->vm_mm,
+ (pte_young(pteval) || folio_test_young(folio) ||
+ folio_test_referenced(folio) || mmu_notifier_test_young(vma->vm_mm,
address)))
referenced++;
}
@@ -1402,7 +1400,7 @@ out_unmap:
*mmap_locked = false;
}
out:
- trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
+ trace_mm_khugepaged_scan_pmd(mm, &folio->page, writable, referenced,
none_or_zero, result, unmapped);
return result;
}
_
Patches currently in -mm which might be from vishal.moola@xxxxxxxxx are
mm-khugepaged-convert-__collapse_huge_page_isolate-to-use-folios.patch
mm-khugepaged-convert-hpage_collapse_scan_pmd-to-use-folios.patch
mm-khugepaged-convert-is_refcount_suitable-to-use-folios.patch
mm-khugepaged-convert-alloc_charge_hpage-to-use-folios.patch
mm-khugepaged-convert-collapse_pte_mapped_thp-to-use-folios.patch
