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Message-ID: <20230218002819.1486479-6-jthoughton@google.com>
Date: Sat, 18 Feb 2023 00:27:38 +0000
From: James Houghton <jthoughton@...gle.com>
To: Mike Kravetz <mike.kravetz@...cle.com>,
Muchun Song <songmuchun@...edance.com>,
Peter Xu <peterx@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...hat.com>,
David Rientjes <rientjes@...gle.com>,
Axel Rasmussen <axelrasmussen@...gle.com>,
Mina Almasry <almasrymina@...gle.com>,
"Zach O'Keefe" <zokeefe@...gle.com>,
Manish Mishra <manish.mishra@...anix.com>,
Naoya Horiguchi <naoya.horiguchi@....com>,
"Dr . David Alan Gilbert" <dgilbert@...hat.com>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Vlastimil Babka <vbabka@...e.cz>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Yang Shi <shy828301@...il.com>,
Frank van der Linden <fvdl@...gle.com>,
Jiaqi Yan <jiaqiyan@...gle.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
James Houghton <jthoughton@...gle.com>
Subject: [PATCH v2 05/46] rmap: hugetlb: switch from page_dup_file_rmap to page_add_file_rmap
This only applies to file-backed HugeTLB, and it should be a no-op until
high-granularity mapping is possible. Also update page_remove_rmap to
support the eventual case where !compound && folio_test_hugetlb().
HugeTLB doesn't use LRU or mlock, so we avoid those bits. This also
means we don't need to use subpage_mapcount; if we did, it would
overflow with only a few mappings.
There is still one caller of page_dup_file_rmap left: copy_present_pte,
and it is always called with compound=false in this case.
Signed-off-by: James Houghton <jthoughton@...gle.com>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 08004371cfed..6c008c9de80e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5077,7 +5077,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
* sleep during the process.
*/
if (!PageAnon(ptepage)) {
- page_dup_file_rmap(ptepage, true);
+ page_add_file_rmap(ptepage, src_vma, true);
} else if (page_try_dup_anon_rmap(ptepage, true,
src_vma)) {
pte_t src_pte_old = entry;
@@ -5910,7 +5910,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
if (anon_rmap)
hugepage_add_new_anon_rmap(folio, vma, haddr);
else
- page_dup_file_rmap(&folio->page, true);
+ page_add_file_rmap(&folio->page, vma, true);
new_pte = make_huge_pte(vma, &folio->page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
/*
@@ -6301,7 +6301,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
goto out_release_unlock;
if (folio_in_pagecache)
- page_dup_file_rmap(&folio->page, true);
+ page_add_file_rmap(&folio->page, dst_vma, true);
else
hugepage_add_new_anon_rmap(folio, dst_vma, dst_addr);
diff --git a/mm/migrate.c b/mm/migrate.c
index d3964c414010..b0f87f19b536 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -254,7 +254,7 @@ static bool remove_migration_pte(struct folio *folio,
hugepage_add_anon_rmap(new, vma, pvmw.address,
rmap_flags);
else
- page_dup_file_rmap(new, true);
+ page_add_file_rmap(new, vma, true);
set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
} else
#endif
diff --git a/mm/rmap.c b/mm/rmap.c
index 15ae24585fc4..c010d0af3a82 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1318,21 +1318,21 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
int nr = 0, nr_pmdmapped = 0;
bool first;
- VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
+ VM_BUG_ON_PAGE(compound && !PageTransHuge(page)
+ && !folio_test_hugetlb(folio), page);
/* Is page being mapped by PTE? Is this its first map to be added? */
if (likely(!compound)) {
first = atomic_inc_and_test(&page->_mapcount);
nr = first;
- if (first && folio_test_large(folio)) {
+ if (first && folio_test_large(folio)
+ && !folio_test_hugetlb(folio)) {
nr = atomic_inc_return_relaxed(mapped);
nr = (nr < COMPOUND_MAPPED);
}
- } else if (folio_test_pmd_mappable(folio)) {
- /* That test is redundant: it's for safety or to optimize out */
-
+ } else {
first = atomic_inc_and_test(&folio->_entire_mapcount);
- if (first) {
+ if (first && !folio_test_hugetlb(folio)) {
nr = atomic_add_return_relaxed(COMPOUND_MAPPED, mapped);
if (likely(nr < COMPOUND_MAPPED + COMPOUND_MAPPED)) {
nr_pmdmapped = folio_nr_pages(folio);
@@ -1347,6 +1347,9 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
}
}
+ if (folio_test_hugetlb(folio))
+ return;
+
if (nr_pmdmapped)
__lruvec_stat_mod_folio(folio, folio_test_swapbacked(folio) ?
NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped);
@@ -1376,8 +1379,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
VM_BUG_ON_PAGE(compound && !PageHead(page), page);
/* Hugetlb pages are not counted in NR_*MAPPED */
- if (unlikely(folio_test_hugetlb(folio))) {
- /* hugetlb pages are always mapped with pmds */
+ if (unlikely(folio_test_hugetlb(folio)) && compound) {
atomic_dec(&folio->_entire_mapcount);
return;
}
@@ -1386,15 +1388,14 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
if (likely(!compound)) {
last = atomic_add_negative(-1, &page->_mapcount);
nr = last;
- if (last && folio_test_large(folio)) {
+ if (last && folio_test_large(folio)
+ && !folio_test_hugetlb(folio)) {
nr = atomic_dec_return_relaxed(mapped);
nr = (nr < COMPOUND_MAPPED);
}
- } else if (folio_test_pmd_mappable(folio)) {
- /* That test is redundant: it's for safety or to optimize out */
-
+ } else {
last = atomic_add_negative(-1, &folio->_entire_mapcount);
- if (last) {
+ if (last && !folio_test_hugetlb(folio)) {
nr = atomic_sub_return_relaxed(COMPOUND_MAPPED, mapped);
if (likely(nr < COMPOUND_MAPPED)) {
nr_pmdmapped = folio_nr_pages(folio);
@@ -1409,6 +1410,9 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
}
}
+ if (folio_test_hugetlb(folio))
+ return;
+
if (nr_pmdmapped) {
if (folio_test_anon(folio))
idx = NR_ANON_THPS;
--
2.39.2.637.g21b0678d19-goog
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