[PATCH 07/16] page-flags: define behavior SL*B-related flags on compound pages

From: Kirill A. Shutemov
Date: Thu Sep 24 2015 - 10:57:57 EST


SL*B uses compound pages and marks head pages with PG_slab.
__SetPageSlab() and __ClearPageSlab() are never called for tail pages.

The same situation with PG_slob_free in SLOB allocator.

PF_NO_TAIL is appropriate for these flags.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
include/linux/page-flags.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 10b75615ddf2..c9cd82310e2d 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -254,7 +254,8 @@ PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
TESTCLEARFLAG(Active, active, PF_HEAD)
-__PAGEFLAG(Slab, slab, PF_ANY)
+__PAGEFLAG(Slab, slab, PF_NO_TAIL)
+__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
PAGEFLAG(Pinned, pinned, PF_ANY) TESTSCFLAG(Pinned, pinned, PF_ANY) /* Xen */
PAGEFLAG(SavePinned, savepinned, PF_ANY); /* Xen */
@@ -264,8 +265,6 @@ PAGEFLAG(SwapBacked, swapbacked, PF_ANY)
__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_ANY)
__SETPAGEFLAG(SwapBacked, swapbacked, PF_ANY)

-__PAGEFLAG(SlobFree, slob_free, PF_ANY)
-
/*
* Private page markings that may be used by the filesystem that owns the page
* for its own purposes.
--
2.5.1

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