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mm: page_table_check: use new iteration API

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The page_ext_next() function assumes that page extension objects for a
page order allocation always reside in the same memory section, which may
not be true and could lead to crashes.  Use the new page_ext iteration API
instead.

Link: https://lkml.kernel.org/r/ca2d53a020fe1cd65c442627ff6c0c40d591cbd8.1741301089.git.luizcap@redhat.com
Fixes: cf54f310d0d3 ("mm/hugetlb: use __GFP_COMP for gigantic folios")
Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Luiz Capitulino 2025-03-06 17:44:51 -05:00 committed by Andrew Morton
parent 9039b9096e
commit 4e30b94cda
1 changed files with 12 additions and 27 deletions
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39
mm/page_table_check.c
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@ -62,24 +62,20 @@ static struct page_table_check *get_page_table_check(struct page_ext *page_ext)
*/
static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt)
{
struct page_ext_iter iter;
struct page_ext *page_ext;
struct page *page;
unsigned long i;
bool anon;
if (!pfn_valid(pfn))
return;
page = pfn_to_page(pfn);
page_ext = page_ext_get(page);
if (!page_ext)
return;
BUG_ON(PageSlab(page));
anon = PageAnon(page);
for (i = 0; i < pgcnt; i++) {
rcu_read_lock();
for_each_page_ext(page, pgcnt, page_ext, iter) {
struct page_table_check *ptc = get_page_table_check(page_ext);
if (anon) {
@ -89,9 +85,8 @@ static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt)
BUG_ON(atomic_read(&ptc->anon_map_count));
BUG_ON(atomic_dec_return(&ptc->file_map_count) < 0);
}
page_ext = page_ext_next(page_ext);
}
page_ext_put(page_ext);
rcu_read_unlock();
}
/*
@ -102,24 +97,20 @@ static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt)
static void page_table_check_set(unsigned long pfn, unsigned long pgcnt,
bool rw)
{
struct page_ext_iter iter;
struct page_ext *page_ext;
struct page *page;
unsigned long i;
bool anon;
if (!pfn_valid(pfn))
return;
page = pfn_to_page(pfn);
page_ext = page_ext_get(page);
if (!page_ext)
return;
BUG_ON(PageSlab(page));
anon = PageAnon(page);
for (i = 0; i < pgcnt; i++) {
rcu_read_lock();
for_each_page_ext(page, pgcnt, page_ext, iter) {
struct page_table_check *ptc = get_page_table_check(page_ext);
if (anon) {
@ -129,9 +120,8 @@ static void page_table_check_set(unsigned long pfn, unsigned long pgcnt,
BUG_ON(atomic_read(&ptc->anon_map_count));
BUG_ON(atomic_inc_return(&ptc->file_map_count) < 0);
}
page_ext = page_ext_next(page_ext);
}
page_ext_put(page_ext);
rcu_read_unlock();
}
/*
@ -140,24 +130,19 @@ static void page_table_check_set(unsigned long pfn, unsigned long pgcnt,
*/
void __page_table_check_zero(struct page *page, unsigned int order)
{
struct page_ext_iter iter;
struct page_ext *page_ext;
unsigned long i;
BUG_ON(PageSlab(page));
page_ext = page_ext_get(page);
if (!page_ext)
return;
for (i = 0; i < (1ul << order); i++) {
rcu_read_lock();
for_each_page_ext(page, 1 << order, page_ext, iter) {
struct page_table_check *ptc = get_page_table_check(page_ext);
BUG_ON(atomic_read(&ptc->anon_map_count));
BUG_ON(atomic_read(&ptc->file_map_count));
page_ext = page_ext_next(page_ext);
}
page_ext_put(page_ext);
rcu_read_unlock();
}
void __page_table_check_pte_clear(struct mm_struct *mm, pte_t pte)