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Message-Id: <20220126095557.32392-8-david@redhat.com>
Date: Wed, 26 Jan 2022 10:55:55 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
David Rientjes <rientjes@...gle.com>,
Shakeel Butt <shakeelb@...gle.com>,
John Hubbard <jhubbard@...dia.com>,
Jason Gunthorpe <jgg@...dia.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Yang Shi <shy828301@...il.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Matthew Wilcox <willy@...radead.org>,
Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
Michal Hocko <mhocko@...nel.org>,
Nadav Amit <namit@...are.com>, Rik van Riel <riel@...riel.com>,
Roman Gushchin <guro@...com>,
Andrea Arcangeli <aarcange@...hat.com>,
Peter Xu <peterx@...hat.com>,
Donald Dutile <ddutile@...hat.com>,
Christoph Hellwig <hch@....de>,
Oleg Nesterov <oleg@...hat.com>, Jan Kara <jack@...e.cz>,
Liang Zhang <zhangliang5@...wei.com>, linux-mm@...ck.org,
David Hildenbrand <david@...hat.com>
Subject: [PATCH RFC v2 7/9] mm/swapfile: remove reuse_swap_page()
All users are gone, let's remove it. We'll let SWP_STABLE_WRITES stick
around for now, as it might come in handy in the near future.
Signed-off-by: David Hildenbrand <david@...hat.com>
---
include/linux/swap.h | 4 --
mm/swapfile.c | 104 -------------------------------------------
2 files changed, 108 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1d38d9475c4d..b546e4bd5c5a 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -514,7 +514,6 @@ extern int __swp_swapcount(swp_entry_t entry);
extern int swp_swapcount(swp_entry_t entry);
extern struct swap_info_struct *page_swap_info(struct page *);
extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
-extern bool reuse_swap_page(struct page *);
extern int try_to_free_swap(struct page *);
struct backing_dev_info;
extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
@@ -680,9 +679,6 @@ static inline int swp_swapcount(swp_entry_t entry)
return 0;
}
-#define reuse_swap_page(page) \
- (page_trans_huge_mapcount(page) == 1)
-
static inline int try_to_free_swap(struct page *page)
{
return 0;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index bf0df7aa7158..a5183315dc58 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1167,16 +1167,6 @@ static struct swap_info_struct *_swap_info_get(swp_entry_t entry)
return NULL;
}
-static struct swap_info_struct *swap_info_get(swp_entry_t entry)
-{
- struct swap_info_struct *p;
-
- p = _swap_info_get(entry);
- if (p)
- spin_lock(&p->lock);
- return p;
-}
-
static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry,
struct swap_info_struct *q)
{
@@ -1601,100 +1591,6 @@ static bool page_swapped(struct page *page)
return false;
}
-static int page_trans_huge_map_swapcount(struct page *page,
- int *total_swapcount)
-{
- int i, map_swapcount, _total_swapcount;
- unsigned long offset = 0;
- struct swap_info_struct *si;
- struct swap_cluster_info *ci = NULL;
- unsigned char *map = NULL;
- int swapcount = 0;
-
- /* hugetlbfs shouldn't call it */
- VM_BUG_ON_PAGE(PageHuge(page), page);
-
- if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) {
- if (PageSwapCache(page))
- swapcount = page_swapcount(page);
- if (total_swapcount)
- *total_swapcount = swapcount;
- return swapcount + page_trans_huge_mapcount(page);
- }
-
- page = compound_head(page);
-
- _total_swapcount = map_swapcount = 0;
- if (PageSwapCache(page)) {
- swp_entry_t entry;
-
- entry.val = page_private(page);
- si = _swap_info_get(entry);
- if (si) {
- map = si->swap_map;
- offset = swp_offset(entry);
- }
- }
- if (map)
- ci = lock_cluster(si, offset);
- for (i = 0; i < HPAGE_PMD_NR; i++) {
- int mapcount = atomic_read(&page[i]._mapcount) + 1;
- if (map) {
- swapcount = swap_count(map[offset + i]);
- _total_swapcount += swapcount;
- }
- map_swapcount = max(map_swapcount, mapcount + swapcount);
- }
- unlock_cluster(ci);
-
- if (PageDoubleMap(page))
- map_swapcount -= 1;
-
- if (total_swapcount)
- *total_swapcount = _total_swapcount;
-
- return map_swapcount + compound_mapcount(page);
-}
-
-/*
- * We can write to an anon page without COW if there are no other references
- * to it. And as a side-effect, free up its swap: because the old content
- * on disk will never be read, and seeking back there to write new content
- * later would only waste time away from clustering.
- */
-bool reuse_swap_page(struct page *page)
-{
- int count, total_swapcount;
-
- VM_BUG_ON_PAGE(!PageLocked(page), page);
- if (unlikely(PageKsm(page)))
- return false;
- count = page_trans_huge_map_swapcount(page, &total_swapcount);
- if (count == 1 && PageSwapCache(page) &&
- (likely(!PageTransCompound(page)) ||
- /* The remaining swap count will be freed soon */
- total_swapcount == page_swapcount(page))) {
- if (!PageWriteback(page)) {
- page = compound_head(page);
- delete_from_swap_cache(page);
- SetPageDirty(page);
- } else {
- swp_entry_t entry;
- struct swap_info_struct *p;
-
- entry.val = page_private(page);
- p = swap_info_get(entry);
- if (p->flags & SWP_STABLE_WRITES) {
- spin_unlock(&p->lock);
- return false;
- }
- spin_unlock(&p->lock);
- }
- }
-
- return count <= 1;
-}
-
/*
* If swap is getting full, or if there are no more mappings of this page,
* then try_to_free_swap is called to free its swap space.
--
2.34.1
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