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Message-Id: <20231016200510.7387-2-vishal.moola@gmail.com>
Date: Mon, 16 Oct 2023 13:05:06 -0700
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
shy828301@...il.com,
"Vishal Moola (Oracle)" <vishal.moola@...il.com>,
Matthew Wilcox <willy@...radead.org>
Subject: [PATCH 1/5] mm/khugepaged: Convert __collapse_huge_page_isolate() to use folios
Replaces 11 calls to compound_head() with 1, and removes 1375 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.
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
mm/khugepaged.c | 51 ++++++++++++++++++++++++-------------------------
1 file changed, 25 insertions(+), 26 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 88433cc25d8a..7a552fe16c92 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -541,7 +541,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
struct collapse_control *cc,
struct list_head *compound_pagelist)
{
- struct page *page = NULL;
+ struct folio *folio = NULL;
pte_t *_pte;
int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0;
bool writable = false;
@@ -570,15 +570,15 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
result = SCAN_PTE_UFFD_WP;
goto out;
}
- 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;
}
- VM_BUG_ON_PAGE(!PageAnon(page), page);
+ VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio);
- if (page_mapcount(page) > 1) {
+ if (folio_estimated_sharers(folio) > 1) {
++shared;
if (cc->is_khugepaged &&
shared > khugepaged_max_ptes_shared) {
@@ -588,16 +588,15 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
}
}
- if (PageCompound(page)) {
- struct page *p;
- page = compound_head(page);
+ if (folio_test_large(folio)) {
+ struct folio *f;
/*
* Check if we have dealt with the compound page
* already
*/
- list_for_each_entry(p, compound_pagelist, lru) {
- if (page == p)
+ list_for_each_entry(f, compound_pagelist, lru) {
+ if (folio == f)
goto next;
}
}
@@ -608,7 +607,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
* is needed to serialize against split_huge_page
* when invoked from the VM.
*/
- if (!trylock_page(page)) {
+ if (!folio_trylock(folio)) {
result = SCAN_PAGE_LOCK;
goto out;
}
@@ -624,8 +623,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
* but not from this process. The other process cannot write to
* the page, only trigger CoW.
*/
- if (!is_refcount_suitable(page)) {
- unlock_page(page);
+ if (!is_refcount_suitable(&folio->page)) {
+ folio_unlock(folio);
result = SCAN_PAGE_COUNT;
goto out;
}
@@ -634,27 +633,27 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
* Isolate the page to avoid collapsing an hugepage
* currently in use by the VM.
*/
- if (!isolate_lru_page(page)) {
- unlock_page(page);
+ if (!folio_isolate_lru(folio)) {
+ folio_unlock(folio);
result = SCAN_DEL_PAGE_LRU;
goto out;
}
- mod_node_page_state(page_pgdat(page),
- NR_ISOLATED_ANON + page_is_file_lru(page),
- compound_nr(page));
- VM_BUG_ON_PAGE(!PageLocked(page), page);
- VM_BUG_ON_PAGE(PageLRU(page), page);
+ node_stat_mod_folio(folio,
+ NR_ISOLATED_ANON + folio_is_file_lru(folio),
+ folio_nr_pages(folio));
+ VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+ VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
- if (PageCompound(page))
- list_add_tail(&page->lru, compound_pagelist);
+ if (folio_test_large(folio))
+ list_add_tail(&folio->lru, compound_pagelist);
next:
/*
* If collapse was initiated by khugepaged, check that there is
* 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++;
@@ -668,13 +667,13 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
result = SCAN_LACK_REFERENCED_PAGE;
} else {
result = SCAN_SUCCEED;
- trace_mm_collapse_huge_page_isolate(page, none_or_zero,
+ trace_mm_collapse_huge_page_isolate(&folio->page, none_or_zero,
referenced, writable, result);
return result;
}
out:
release_pte_pages(pte, _pte, compound_pagelist);
- trace_mm_collapse_huge_page_isolate(page, none_or_zero,
+ trace_mm_collapse_huge_page_isolate(&folio->page, none_or_zero,
referenced, writable, result);
return result;
}
--
2.40.1
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