page-flags: define PG_locked behavior on compound pages
lock_page() must operate on the whole compound page. It doesn't make
much sense to lock part of compound page. Change code to use head
page's PG_locked, if tail page is passed.
This patch also gets rid of custom helper functions --
__set_page_locked() and __clear_page_locked(). They are replaced with
helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG. Tail pages to these
helper would trigger VM_BUG_ON().
SLUB uses PG_locked as a bit spin locked. IIUC, tail pages should never
appear there. VM_BUG_ON() is added to make sure that this assumption is
correct.
[akpm@linux-foundation.org: fix fs/cifs/file.c]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swap_state.c b/mm/swap_state.c
index d504adb..d783872 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -353,7 +353,7 @@
}
/* May fail (-ENOMEM) if radix-tree node allocation failed. */
- __set_page_locked(new_page);
+ __SetPageLocked(new_page);
SetPageSwapBacked(new_page);
err = __add_to_swap_cache(new_page, entry);
if (likely(!err)) {
@@ -367,7 +367,7 @@
}
radix_tree_preload_end();
ClearPageSwapBacked(new_page);
- __clear_page_locked(new_page);
+ __ClearPageLocked(new_page);
/*
* add_to_swap_cache() doesn't return -EEXIST, so we can safely
* clear SWAP_HAS_CACHE flag.