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authorHugh Dickins <hughd@google.com>2016-05-19 17:12:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-19 19:12:14 -0700
commitfa9949da59a15017a02c86b087c7499d7b5702be (patch)
tree1191eac8b64eb3ba21b1286d9f3842db0388af82 /mm/migrate.c
parent9d5e6a9f22311b00a20ff9b072760ad3e73f0d99 (diff)
downloadop-kernel-dev-fa9949da59a15017a02c86b087c7499d7b5702be.zip
op-kernel-dev-fa9949da59a15017a02c86b087c7499d7b5702be.tar.gz
mm: use __SetPageSwapBacked and dont ClearPageSwapBacked
v3.16 commit 07a427884348 ("mm: shmem: avoid atomic operation during shmem_getpage_gfp") rightly replaced one instance of SetPageSwapBacked by __SetPageSwapBacked, pointing out that the newly allocated page is not yet visible to other users (except speculative get_page_unless_zero- ers, who may not update page flags before their further checks). That was part of a series in which Mel was focused on tmpfs profiles: but almost all SetPageSwapBacked uses can be so optimized, with the same justification. Remove ClearPageSwapBacked from __read_swap_cache_async() error path: it's not an error to free a page with PG_swapbacked set. Follow a convention of __SetPageLocked, __SetPageSwapBacked instead of doing it differently in different places; but that's for tidiness - if the ordering actually mattered, we should not be using the __variants. There's probably scope for further __SetPageFlags in other places, but SwapBacked is the one I'm interested in at the moment. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Reviewed-by: Mel Gorman <mgorman@techsingularity.net> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
-rw-r--r--mm/migrate.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index f9dfb18..53ab639 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -332,7 +332,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
newpage->index = page->index;
newpage->mapping = page->mapping;
if (PageSwapBacked(page))
- SetPageSwapBacked(newpage);
+ __SetPageSwapBacked(newpage);
return MIGRATEPAGE_SUCCESS;
}
@@ -378,7 +378,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
newpage->index = page->index;
newpage->mapping = page->mapping;
if (PageSwapBacked(page))
- SetPageSwapBacked(newpage);
+ __SetPageSwapBacked(newpage);
get_page(newpage); /* add cache reference */
if (PageSwapCache(page)) {
@@ -1791,7 +1791,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
/* Prepare a page as a migration target */
__SetPageLocked(new_page);
- SetPageSwapBacked(new_page);
+ __SetPageSwapBacked(new_page);
/* anon mapping, we can simply copy page->mapping to the new page: */
new_page->mapping = page->mapping;
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