Make should_zap_page() to take a folio and use a folio in
zap_pte_range(), which save several compound_head() calls.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
mm/memory.c | 45 +++++++++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 20 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index d9314dee355e..806568f9605b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1358,19 +1358,19 @@ static inline bool should_zap_cows(struct zap_details *details)
return details->even_cows;
}
-/* Decides whether we should zap this page with the page pointer specified */
-static inline bool should_zap_page(struct zap_details *details, struct page *page)
+/* Decides whether we should zap this folio with the folio pointer specified */
+static inline bool should_zap_page(struct zap_details *details, struct folio *folio)
{
- /* If we can make a decision without *page.. */
+ /* If we can make a decision without *folio.. */
if (should_zap_cows(details))
return true;
- /* E.g. the caller passes NULL for the case of a zero page */
- if (!page)
+ /* E.g. the caller passes NULL for the case of a zero folio */
+ if (!folio)
return true;
- /* Otherwise we should only zap non-anon pages */
- return !PageAnon(page);
+ /* Otherwise we should only zap non-anon folios */
+ return !folio_test_anon(folio);
}
static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
@@ -1423,7 +1423,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
arch_enter_lazy_mmu_mode();
do {
pte_t ptent = ptep_get(pte);
- struct page *page;
+ struct folio *folio = NULL;
if (pte_none(ptent))
continue;
@@ -1433,9 +1433,13 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
if (pte_present(ptent)) {
unsigned int delay_rmap;
+ struct page *page;
page = vm_normal_page(vma, addr, ptent);
- if (unlikely(!should_zap_page(details, page)))
+ if (page)
+ folio = page_folio(page);
+
+ if (unlikely(!should_zap_page(details, folio)))
continue;
ptent = ptep_get_and_clear_full(mm, addr, pte,
tlb->fullmm);
@@ -1449,16 +1453,16 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
}
delay_rmap = 0;
- if (!PageAnon(page)) {
+ if (!folio_test_anon(folio)) {
if (pte_dirty(ptent)) {
- set_page_dirty(page);
+ folio_set_dirty(folio);
if (tlb_delay_rmap(tlb)) {
delay_rmap = 1;
force_flush = 1;
}
}
if (pte_young(ptent) && likely(vma_has_recency(vma)))
- mark_page_accessed(page);
+ folio_mark_accessed(folio);
}
rss[mm_counter(page)]--;
if (!delay_rmap) {
@@ -1477,9 +1481,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
entry = pte_to_swp_entry(ptent);
if (is_device_private_entry(entry) ||
is_device_exclusive_entry(entry)) {
- page = pfn_swap_entry_to_page(entry);
- if (unlikely(!should_zap_page(details, page)))
+ folio = pfn_swap_entry_to_folio(entry);
+ if (unlikely(!should_zap_page(details, folio)))
continue;
+
/*
* Both device private/exclusive mappings should only
* work with anonymous page so far, so we don't need to
@@ -1487,10 +1492,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
* see zap_install_uffd_wp_if_needed().
*/
WARN_ON_ONCE(!vma_is_anonymous(vma));
- rss[mm_counter(page)]--;
+ rss[mm_counter(&folio->page)]--;
if (is_device_private_entry(entry))
- page_remove_rmap(page, vma, false);
- put_page(page);
+ page_remove_rmap(&folio->page, vma, false);
+ folio_put(folio);
} else if (!non_swap_entry(entry)) {
/* Genuine swap entry, hence a private anon page */
if (!should_zap_cows(details))
@@ -1499,10 +1504,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
if (unlikely(!free_swap_and_cache(entry)))
print_bad_pte(vma, addr, ptent, NULL);
} else if (is_migration_entry(entry)) {
- page = pfn_swap_entry_to_page(entry);
- if (!should_zap_page(details, page))
+ folio = pfn_swap_entry_to_folio(entry);
+ if (!should_zap_page(details, folio))
continue;
- rss[mm_counter(page)]--;
+ rss[mm_counter(&folio->page)]--;
} else if (pte_marker_entry_uffd_wp(entry)) {
/*
* For anon: always drop the marker; for file: only
--
2.27.0On Sat, Nov 04, 2023 at 11:55:18AM +0800, Kefeng Wang wrote: > -/* Decides whether we should zap this page with the page pointer specified */ > -static inline bool should_zap_page(struct zap_details *details, struct page *page) > +/* Decides whether we should zap this folio with the folio pointer specified */ > +static inline bool should_zap_page(struct zap_details *details, struct folio *folio) Surely we should rename this to should_zap_folio()? > @@ -1487,10 +1492,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, > * see zap_install_uffd_wp_if_needed(). > */ > WARN_ON_ONCE(!vma_is_anonymous(vma)); > - rss[mm_counter(page)]--; > + rss[mm_counter(&folio->page)]--; > if (is_device_private_entry(entry)) > - page_remove_rmap(page, vma, false); > - put_page(page); > + page_remove_rmap(&folio->page, vma, false); > + folio_put(folio); This is wrong. If we have a PTE-mapped THP, you'll remove the head page N times instead of removing each of N pages. I suspect you're going to collide with Ryan's work by doing this ...
On 2023/11/5 1:20, Matthew Wilcox wrote: > On Sat, Nov 04, 2023 at 11:55:18AM +0800, Kefeng Wang wrote: >> -/* Decides whether we should zap this page with the page pointer specified */ >> -static inline bool should_zap_page(struct zap_details *details, struct page *page) >> +/* Decides whether we should zap this folio with the folio pointer specified */ >> +static inline bool should_zap_page(struct zap_details *details, struct folio *folio) > > Surely we should rename this to should_zap_folio()? Will update. > >> @@ -1487,10 +1492,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, >> * see zap_install_uffd_wp_if_needed(). >> */ >> WARN_ON_ONCE(!vma_is_anonymous(vma)); >> - rss[mm_counter(page)]--; >> + rss[mm_counter(&folio->page)]--; >> if (is_device_private_entry(entry)) >> - page_remove_rmap(page, vma, false); >> - put_page(page); >> + page_remove_rmap(&folio->page, vma, false); >> + folio_put(folio); > > This is wrong. If we have a PTE-mapped THP, you'll remove the head page > N times instead of removing each of N pages. This is device private entry, I suppose that it won't be a THP and large folio when check migrate_vma_check_page() and migrate_vma_insert_page(), right? > > I suspect you're going to collide with Ryan's work by doing this ... > Maybe not if the above is true, at least for now. Thanks.
On Mon, Nov 06, 2023 at 10:30:59AM +0800, Kefeng Wang wrote: > On 2023/11/5 1:20, Matthew Wilcox wrote: > > > - page_remove_rmap(page, vma, false); > > > - put_page(page); > > > + page_remove_rmap(&folio->page, vma, false); > > > + folio_put(folio); > > > > This is wrong. If we have a PTE-mapped THP, you'll remove the head page > > N times instead of removing each of N pages. > > This is device private entry, I suppose that it won't be a THP and large > folio when check migrate_vma_check_page() and migrate_vma_insert_page(), > right? I don't want to leave that kind of booby-trap in the code. Both places which currently call page_remove_rmap() should be left as referring to the page, not the folio.
On 2023/11/6 22:20, Matthew Wilcox wrote: > On Mon, Nov 06, 2023 at 10:30:59AM +0800, Kefeng Wang wrote: >> On 2023/11/5 1:20, Matthew Wilcox wrote: >>>> - page_remove_rmap(page, vma, false); >>>> - put_page(page); >>>> + page_remove_rmap(&folio->page, vma, false); >>>> + folio_put(folio); >>> >>> This is wrong. If we have a PTE-mapped THP, you'll remove the head page >>> N times instead of removing each of N pages. >> >> This is device private entry, I suppose that it won't be a THP and large >> folio when check migrate_vma_check_page() and migrate_vma_insert_page(), >> right? > > I don't want to leave that kind of booby-trap in the code. Both places > which currently call page_remove_rmap() should be left as referring to > the page, not the folio. Sure, I will fix this, also page_try_dup_anon_rmap() for device private entry in copy_nonpresent_pte of patch5.
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