linux-kernel - [PATCH v2 1/4] mm/page_alloc.c: cleanup obsolete KM

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Date:	Mon,  4 May 2015 23:16:55 +0200
From:	Anisse Astier <anisse@...ier.eu>
To:	unlisted-recipients:; (no To-header on input)
Cc:	Anisse Astier <anisse@...ier.eu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	David Rientjes <rientjes@...gle.com>,
	Alan Cox <gnomes@...rguk.ukuu.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	PaX Team <pageexec@...email.hu>,
	Brad Spengler <spender@...ecurity.net>,
	Kees Cook <keescook@...omium.org>,
	Andi Kleen <andi@...stfloor.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/4] mm/page_alloc.c: cleanup obsolete KM_USER*

It's been five years now that KM_* kmap flags have been removed and
that we can call clear_highpage from any context. So we remove
prep_zero_pages accordingly.

Signed-off-by: Anisse Astier <anisse@...ier.eu>
---
 mm/page_alloc.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ebffa0e..4d5ce6e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -380,20 +380,6 @@ void prep_compound_page(struct page *page, unsigned long order)
 	}
 }
 
-static inline void prep_zero_page(struct page *page, unsigned int order,
-							gfp_t gfp_flags)
-{
-	int i;
-
-	/*
-	 * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
-	 * and __GFP_HIGHMEM from hard or soft interrupt context.
-	 */
-	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
-	for (i = 0; i < (1 << order); i++)
-		clear_highpage(page + i);
-}
-
 #ifdef CONFIG_DEBUG_PAGEALLOC
 unsigned int _debug_guardpage_minorder;
 bool _debug_pagealloc_enabled __read_mostly;
@@ -975,7 +961,8 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
 	kasan_alloc_pages(page, order);
 
 	if (gfp_flags & __GFP_ZERO)
-		prep_zero_page(page, order, gfp_flags);
+		for (i = 0; i < (1 << order); i++)
+			clear_highpage(page + i);
 
 	if (order && (gfp_flags & __GFP_COMP))
 		prep_compound_page(page, order);
-- 
1.9.3

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