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authorDavid Hildenbrand <david@redhat.com>2023-09-13 14:51:10 +0200
committerAndrew Morton <akpm@linux-foundation.org>2023-10-04 10:32:27 -0700
commitc5c540034747dfe450f64d1151081a6080daa8f9 (patch)
tree413ff65dfbb8aba5b1f7fa091963e6bfd9bd6c94 /mm/rmap.c
parentc66db8c0702c0ab741ecfd5e12b323ff49fe9089 (diff)
downloadlwn-c5c540034747dfe450f64d1151081a6080daa8f9.tar.gz
lwn-c5c540034747dfe450f64d1151081a6080daa8f9.zip
mm/rmap: move folio_test_anon() check out of __folio_set_anon()
Let's handle it in the caller; no need for the "first" check based on the mapcount. We really only end up with !anon pages in page_add_anon_rmap() via do_swap_page(), where we hold the folio lock. So races are not possible. Add a VM_WARN_ON_FOLIO() to make sure that we really hold the folio lock. In the future, we might want to let do_swap_page() use folio_add_new_anon_rmap() on new pages instead: however, we might have to pass then whether the folio is exclusive or not. So keep it in there for now. For hugetlb we never expect to have a non-anon page in hugepage_add_anon_rmap(). Remove that code, along with some other checks that are either not required or were checked in hugepage_add_new_anon_rmap() already. Link: https://lkml.kernel.org/r/20230913125113.313322-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c23
1 files changed, 8 insertions, 15 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index f76f0f23725c..65de3832123e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1135,9 +1135,6 @@ static void __folio_set_anon(struct folio *folio, struct vm_area_struct *vma,
BUG_ON(!anon_vma);
- if (folio_test_anon(folio))
- return;
-
/*
* If the folio isn't exclusive to this vma, we must use the _oldest_
* possible anon_vma for the folio mapping!
@@ -1239,12 +1236,12 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
if (nr)
__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
- if (likely(!folio_test_ksm(folio))) {
- if (first)
- __folio_set_anon(folio, vma, address,
- !!(flags & RMAP_EXCLUSIVE));
- else
- __page_check_anon_rmap(folio, page, vma, address);
+ if (unlikely(!folio_test_anon(folio))) {
+ VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
+ __folio_set_anon(folio, vma, address,
+ !!(flags & RMAP_EXCLUSIVE));
+ } else if (likely(!folio_test_ksm(folio))) {
+ __page_check_anon_rmap(folio, page, vma, address);
}
if (flags & RMAP_EXCLUSIVE)
SetPageAnonExclusive(page);
@@ -2541,17 +2538,13 @@ void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
unsigned long address, rmap_t flags)
{
struct folio *folio = page_folio(page);
- struct anon_vma *anon_vma = vma->anon_vma;
int first;
- BUG_ON(!folio_test_locked(folio));
- BUG_ON(!anon_vma);
+ VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
+
first = atomic_inc_and_test(&folio->_entire_mapcount);
VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page);
VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);
- if (first)
- __folio_set_anon(folio, vma, address,
- !!(flags & RMAP_EXCLUSIVE));
if (flags & RMAP_EXCLUSIVE)
SetPageAnonExclusive(page);
}