linux-kernel - [PATCH] mm: remove __GFP_NOFAIL is deprecated comment

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Message-Id: <1456397002-27172-1-git-send-email-mhocko@kernel.org>
Date:	Thu, 25 Feb 2016 11:43:22 +0100
From:	Michal Hocko <mhocko@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Rientjes <rientjes@...gle.com>,
	Nikolay Borisov <kernel@...p.com>, <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...e.com>
Subject: [PATCH] mm: remove __GFP_NOFAIL is deprecated comment

From: Michal Hocko <mhocko@...e.com>

647757197cd3 ("mm: clarify __GFP_NOFAIL deprecation status") was
incomplete and didn't remove the comment about __GFP_NOFAIL being
deprecated in buffered_rmqueue. Let's get rid of this leftover
but keep the WARN_ON_ONCE for order > 1 because we should really
discourage from using __GFP_NOFAIL with higher order allocations
because those are just too subtle.

Signed-off-by: Michal Hocko <mhocko@...e.com>
---
Hi,
this popped out when discussing another patch http://lkml.kernel.org/r/56CEC568.6080809@kyup.com
so I think it is worth removing the comment.

 mm/page_alloc.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1993894b4219..109d975a7172 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2347,19 +2347,11 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 		list_del(&page->lru);
 		pcp->count--;
 	} else {
-		if (unlikely(gfp_flags & __GFP_NOFAIL)) {
-			/*
-			 * __GFP_NOFAIL is not to be used in new code.
-			 *
-			 * All __GFP_NOFAIL callers should be fixed so that they
-			 * properly detect and handle allocation failures.
-			 *
-			 * We most definitely don't want callers attempting to
-			 * allocate greater than order-1 page units with
-			 * __GFP_NOFAIL.
-			 */
-			WARN_ON_ONCE(order > 1);
-		}
+		/*
+		 * We most definitely don't want callers attempting to
+		 * allocate greater than order-1 page units with __GFP_NOFAIL.
+		 */
+		WARN_ON_ONCE(unlikely(gfp_flags & __GFP_NOFAIL) && (order > 1));
 		spin_lock_irqsave(&zone->lock, flags);
 
 		page = NULL;
-- 
2.7.0