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authorNick Piggin <npiggin@suse.de>2006-03-22 00:07:58 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-22 07:53:56 -0800
commit46453a6e194a8c55fe6cf3dc8e1c4f24e2abc013 (patch)
treee407665e6c8cdf33814007750c49fdbea0a21e0e /mm/vmscan.c
parent2492ecc1a16b8ccf679d2999dca4f1b48aef07ee (diff)
[PATCH] mm: never ClearPageLRU released pages
If vmscan finds a zero refcount page on the lru list, never ClearPageLRU it. This means the release code need not hold ->lru_lock to stabilise PageLRU, so that lock may be skipped entirely when releasing !PageLRU pages (because we know PageLRU won't have been temporarily cleared by vmscan, which was previously guaranteed by holding the lock to synchronise against vmscan). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4fe7e3aa02e..acb7611cd52 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1085,21 +1085,25 @@ static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
- if (!TestClearPageLRU(page))
- BUG();
list_del(&page->lru);
- if (get_page_testone(page)) {
+ if (unlikely(get_page_testone(page))) {
/*
* It is being freed elsewhere
*/
__put_page(page);
- SetPageLRU(page);
list_add(&page->lru, src);
continue;
- } else {
- list_add(&page->lru, dst);
- nr_taken++;
}
+
+ /*
+ * 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 (!TestClearPageLRU(page))
+ BUG();
+ list_add(&page->lru, dst);
+ nr_taken++;
}
*scanned = scan;