linux-kernel - [PATCHv3, RFC 08/34] thp, mm: introduce mapping_can_have

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Message-Id: <1365163198-29726-9-git-send-email-kirill.shutemov@linux.intel.com>
Date:	Fri,  5 Apr 2013 14:59:32 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Al Viro <viro@...iv.linux.org.uk>, Hugh Dickins <hughd@...gle.com>,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <matthew.r.wilcox@...el.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Hillf Danton <dhillf@...il.com>, Dave Hansen <dave@...1.net>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv3, RFC 08/34] thp, mm: introduce mapping_can_have_hugepages() predicate

From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>

Returns true if mapping can have huge pages. Just check for __GFP_COMP
in gfp mask of the mapping for now.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 include/linux/pagemap.h |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e3dea75..56debde 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -84,6 +84,17 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
 				(__force unsigned long)mask;
 }
 
+static inline bool mapping_can_have_hugepages(struct address_space *m)
+{
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
+		gfp_t gfp_mask = mapping_gfp_mask(m);
+		/* __GFP_COMP is key part of GFP_TRANSHUGE */
+		return !!(gfp_mask & __GFP_COMP);
+	}
+
+	return false;
+}
+
 /*
  * The page cache can done in larger chunks than
  * one page, because it allows for more efficient
-- 
1.7.10.4

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