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authorHugh Dickins <hughd@google.com>2015-11-06 05:49:49 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-06 06:34:48 +0300
commit7db7671f835ccad66db20154ac1274140937d9b7 (patch)
treefce13f03cda6adf11e7be3cdab26ac7eb91a1145 /mm/balloon_compaction.c
parent2def7424c9be0069831380823fdb5cf72103b919 (diff)
downloadlinux-7db7671f835ccad66db20154ac1274140937d9b7.tar.xz
mm: page migration trylock newpage at same level as oldpage
Clean up page migration a little by moving the trylock of newpage from move_to_new_page() into __unmap_and_move(), where the old page has been locked. Adjust unmap_and_move_huge_page() and balloon_page_migrate() accordingly. But make one kind-of-functional change on the way: whereas trylock of newpage used to BUG() if it failed, now simply return -EAGAIN if so. Cutting out BUG()s is good, right? But, to be honest, this is really to extend the usefulness of the custom put_new_page feature, allowing a pool of new pages to be shared perhaps with racing uses. Use an "else" instead of that "skip_unmap" label. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/balloon_compaction.c')
-rw-r--r--mm/balloon_compaction.c10
1 files changed, 2 insertions, 8 deletions
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index fcad8322ef36..d3116be5a00f 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -199,23 +199,17 @@ int balloon_page_migrate(struct page *newpage,
struct balloon_dev_info *balloon = balloon_page_device(page);
int rc = -EAGAIN;
- /*
- * Block others from accessing the 'newpage' when we get around to
- * establishing additional references. We should be the only one
- * holding a reference to the 'newpage' at this point.
- */
- BUG_ON(!trylock_page(newpage));
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
if (WARN_ON(!__is_movable_balloon_page(page))) {
dump_page(page, "not movable balloon page");
- unlock_page(newpage);
return rc;
}
if (balloon && balloon->migratepage)
rc = balloon->migratepage(balloon, newpage, page, mode);
- unlock_page(newpage);
return rc;
}
#endif /* CONFIG_BALLOON_COMPACTION */