The patch titled
Subject: page-flags: do not corrupt caller 'page' in PF_NO_TAIL
has been added to the -mm tree. Its filename is
page-flags-introduce-page-flags-policies-wrt-compound-pages-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/page-flags-introduce-page-flags-policies-wrt-compound-pages-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/page-flags-introduce-page-flags-policies-wrt-compound-pages-fix.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: page-flags: do not corrupt caller 'page' in PF_NO_TAIL
Andrew noticed that PF_NO_TAIL() modifies caller's 'page'. This doesn't
trigger any bad results, because all users are inline functions which
doesn't use the variable beyond the point. But still not good.
The patch changes PF_NO_TAIL() to always return head page, regardless
'enforce'. This makes operations of page flags with PF_NO_TAIL more
symmetrical: modifications and checks goes to head page. It gives better
chance to recover in case of bug for non-DEBUG_VM kernel.
DEBUG_VM kernel will still trigger VM_BUG_ON() on modifications to tail
pages.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-flags.h | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff -puN include/linux/page-flags.h~page-flags-introduce-page-flags-policies-wrt-compound-pages-fix include/linux/page-flags.h
--- a/include/linux/page-flags.h~page-flags-introduce-page-flags-policies-wrt-compound-pages-fix
+++ a/include/linux/page-flags.h
@@ -160,9 +160,7 @@ static inline int PageCompound(struct pa
#define PF_NO_TAIL(page, enforce) ({ \
if (enforce) \
VM_BUG_ON_PAGE(PageTail(page), page); \
- else \
- page = compound_head(page); \
- page;})
+ compound_head(page);})
#define PF_NO_COMPOUND(page, enforce) ({ \
if (enforce) \
VM_BUG_ON_PAGE(PageCompound(page), page); \
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
rcu-force-alignment-on-struct-callback_head-rcu_head.patch
mm-make-optimistic-check-for-swapin-readahead-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
mm-drop-page-slab_page.patch
slab-slub-use-page-rcu_head-instead-of-page-lru-plus-cast.patch
zsmalloc-use-page-private-instead-of-page-first_page.patch
mm-pack-compound_dtor-and-compound_order-into-one-word-in-struct-page.patch
mm-make-compound_head-robust.patch
mm-make-compound_head-robust-fix.patch
mm-use-unsigned-int-for-page-order.patch
mm-use-unsigned-int-for-compound_dtor-compound_order-on-64bit.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-move-code-around.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages-fix.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-at-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
mm-support-madvisemadv_free-fix-3.patch
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