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authorAlex Shi <alex.shi@linux.alibaba.com>2021-02-24 12:08:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:33 -0800
commitc2135f7c570bc274035834848d9bf46ea89ba763 (patch)
treea0536dce59674a2fc8c9a13dbb644cc43a52f2d4 /mm/vmscan.c
parent7ecc956551f8a66618f71838c790a9b0b4f9ca10 (diff)
mm/vmscan: __isolate_lru_page_prepare() cleanup
The function just returns 2 results, so using a 'switch' to deal with its result is unnecessary. Also simplify it to a bool func as Vlastimil suggested. Also remove 'goto' by reusing list_move(), and take Matthew Wilcox's suggestion to update comments in function. Link: https://lkml.kernel.org/r/728874d7-2d93-4049-68c1-dcc3b2d52ccd@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c68
1 files changed, 31 insertions, 37 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b1b574ad199d..04509994aed4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1539,19 +1539,17 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
* page: page to consider
* mode: one of the LRU isolation modes defined above
*
- * returns 0 on success, -ve errno on failure.
+ * returns true on success, false on failure.
*/
-int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)
+bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)
{
- int ret = -EBUSY;
-
/* Only take pages on the LRU. */
if (!PageLRU(page))
- return ret;
+ return false;
/* Compaction should not handle unevictable pages but CMA can do so */
if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))
- return ret;
+ return false;
/*
* To minimise LRU disruption, the caller can indicate that it only
@@ -1564,7 +1562,7 @@ int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)
if (mode & ISOLATE_ASYNC_MIGRATE) {
/* All the caller can do on PageWriteback is block */
if (PageWriteback(page))
- return ret;
+ return false;
if (PageDirty(page)) {
struct address_space *mapping;
@@ -1580,20 +1578,20 @@ int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)
* from the page cache.
*/
if (!trylock_page(page))
- return ret;
+ return false;
mapping = page_mapping(page);
migrate_dirty = !mapping || mapping->a_ops->migratepage;
unlock_page(page);
if (!migrate_dirty)
- return ret;
+ return false;
}
}
if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
- return ret;
+ return false;
- return 0;
+ return true;
}
/*
@@ -1677,35 +1675,31 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
* only when the page is being freed somewhere else.
*/
scan += nr_pages;
- switch (__isolate_lru_page_prepare(page, mode)) {
- case 0:
- /*
- * Be careful not to clear PageLRU until after we're
- * sure the page is not being freed elsewhere -- the
- * page release code relies on it.
- */
- if (unlikely(!get_page_unless_zero(page)))
- goto busy;
-
- if (!TestClearPageLRU(page)) {
- /*
- * This page may in other isolation path,
- * but we still hold lru_lock.
- */
- put_page(page);
- goto busy;
- }
-
- nr_taken += nr_pages;
- nr_zone_taken[page_zonenum(page)] += nr_pages;
- list_move(&page->lru, dst);
- break;
+ if (!__isolate_lru_page_prepare(page, mode)) {
+ /* It is being freed elsewhere */
+ list_move(&page->lru, src);
+ continue;
+ }
+ /*
+ * Be careful not to clear PageLRU until after we're
+ * sure the page is not being freed elsewhere -- the
+ * page release code relies on it.
+ */
+ if (unlikely(!get_page_unless_zero(page))) {
+ list_move(&page->lru, src);
+ continue;
+ }
- default:
-busy:
- /* else it is being freed elsewhere */
+ if (!TestClearPageLRU(page)) {
+ /* Another thread is already isolating this page */
+ put_page(page);
list_move(&page->lru, src);
+ continue;
}
+
+ nr_taken += nr_pages;
+ nr_zone_taken[page_zonenum(page)] += nr_pages;
+ list_move(&page->lru, dst);
}
/*