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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2011-07-24 10:47:59 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2011-07-24 10:48:00 +0200
commit50a15981a1fac7e019ff7c3cba87531fb580f065 (patch)
tree320ff80a5a01ae6936ac0a83cffb99e1f50adccf /mm/rmap.c
parentf433c4aec9999d1bf2ed8c328196f3b0ad5f75db (diff)
downloadlwn-50a15981a1fac7e019ff7c3cba87531fb580f065.tar.gz
lwn-50a15981a1fac7e019ff7c3cba87531fb580f065.zip
[S390] reference bit testing for unmapped pages
On x86 a page without a mapper is by definition not referenced / old. The s390 architecture keeps the reference bit in the storage key and the current code will check the storage key for page without a mapper. This leads to an interesting effect: the first time an s390 system needs to write pages to swap it only finds referenced pages. This causes a lot of pages to get added and written to the swap device. To avoid this behaviour change page_referenced to query the storage key only if there is a mapper of the page. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 2540a39eea4a..9701574bb67a 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -869,11 +869,11 @@ int page_referenced(struct page *page,
vm_flags);
if (we_locked)
unlock_page(page);
+
+ if (page_test_and_clear_young(page_to_pfn(page)))
+ referenced++;
}
out:
- if (page_test_and_clear_young(page_to_pfn(page)))
- referenced++;
-
return referenced;
}