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Message-ID: <20240411061713.1847574-2-alexs@kernel.org>
Date: Thu, 11 Apr 2024 14:17:02 +0800
From: alexs@...nel.org
To: Andrew Morton <akpm@...ux-foundation.org>,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
zik.eidus@...ellosystems.com,
willy@...radead.org,
aarcange@...hat.com,
hughd@...gle.com,
chrisw@...s-sol.org,
david@...hat.com
Cc: "Alex Shi (tencent)" <alexs@...nel.org>,
Izik Eidus <izik.eidus@...ellosystems.com>
Subject: [PATCH v5 01/10] mm/ksm: add ksm_get_folio
From: "Alex Shi (tencent)" <alexs@...nel.org>
The ksm only contains single pages, so we could add a new func
ksm_get_folio for get_ksm_page to use folio instead of pages to save a
couple of compound_head calls.
After all caller replaced, get_ksm_page will be removed.
Cc: Izik Eidus <izik.eidus@...ellosystems.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Chris Wright <chrisw@...s-sol.org>
Signed-off-by: Alex Shi (tencent) <alexs@...nel.org>
Reviewed-by: David Hildenbrand <david@...hat.com>
---
mm/ksm.c | 42 +++++++++++++++++++++++++-----------------
1 file changed, 25 insertions(+), 17 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index 8c001819cf10..ac126a4c245c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -897,7 +897,7 @@ enum get_ksm_page_flags {
};
/*
- * get_ksm_page: checks if the page indicated by the stable node
+ * ksm_get_folio: checks if the page indicated by the stable node
* is still its ksm page, despite having held no reference to it.
* In which case we can trust the content of the page, and it
* returns the gotten page; but if the page has now been zapped,
@@ -915,10 +915,10 @@ enum get_ksm_page_flags {
* a page to put something that might look like our key in page->mapping.
* is on its way to being freed; but it is an anomaly to bear in mind.
*/
-static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
+static struct folio *ksm_get_folio(struct ksm_stable_node *stable_node,
enum get_ksm_page_flags flags)
{
- struct page *page;
+ struct folio *folio;
void *expected_mapping;
unsigned long kpfn;
@@ -926,8 +926,8 @@ static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
PAGE_MAPPING_KSM);
again:
kpfn = READ_ONCE(stable_node->kpfn); /* Address dependency. */
- page = pfn_to_page(kpfn);
- if (READ_ONCE(page->mapping) != expected_mapping)
+ folio = pfn_folio(kpfn);
+ if (READ_ONCE(folio->mapping) != expected_mapping)
goto stale;
/*
@@ -940,41 +940,41 @@ static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
* in folio_migrate_mapping(), it might still be our page,
* in which case it's essential to keep the node.
*/
- while (!get_page_unless_zero(page)) {
+ while (!folio_try_get(folio)) {
/*
* Another check for page->mapping != expected_mapping would
* work here too. We have chosen the !PageSwapCache test to
* optimize the common case, when the page is or is about to
* be freed: PageSwapCache is cleared (under spin_lock_irq)
* in the ref_freeze section of __remove_mapping(); but Anon
- * page->mapping reset to NULL later, in free_pages_prepare().
+ * folio->mapping reset to NULL later, in free_pages_prepare().
*/
- if (!PageSwapCache(page))
+ if (!folio_test_swapcache(folio))
goto stale;
cpu_relax();
}
- if (READ_ONCE(page->mapping) != expected_mapping) {
- put_page(page);
+ if (READ_ONCE(folio->mapping) != expected_mapping) {
+ folio_put(folio);
goto stale;
}
if (flags == GET_KSM_PAGE_TRYLOCK) {
- if (!trylock_page(page)) {
- put_page(page);
+ if (!folio_trylock(folio)) {
+ folio_put(folio);
return ERR_PTR(-EBUSY);
}
} else if (flags == GET_KSM_PAGE_LOCK)
- lock_page(page);
+ folio_lock(folio);
if (flags != GET_KSM_PAGE_NOLOCK) {
- if (READ_ONCE(page->mapping) != expected_mapping) {
- unlock_page(page);
- put_page(page);
+ if (READ_ONCE(folio->mapping) != expected_mapping) {
+ folio_unlock(folio);
+ folio_put(folio);
goto stale;
}
}
- return page;
+ return folio;
stale:
/*
@@ -990,6 +990,14 @@ static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
return NULL;
}
+static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
+ enum get_ksm_page_flags flags)
+{
+ struct folio *folio = ksm_get_folio(stable_node, flags);
+
+ return &folio->page;
+}
+
/*
* Removing rmap_item from stable or unstable tree.
* This function will clean the information from the stable/unstable tree.
--
2.43.0
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