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From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, NeilBrown <neilb@suse.com>,
	LKML <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH 4/6] mm: kvmalloc support __GFP_RETRY_MAYFAIL for all sizes
Date: Fri, 23 Jun 2017 10:53:43 +0200
Message-ID: <20170623085345.11304-5-mhocko@kernel.org> (raw)
In-Reply-To: <20170623085345.11304-1-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

Now that __GFP_RETRY_MAYFAIL has a reasonable semantic regardless of the
request size we can drop the hackish implementation for !costly orders.
__GFP_RETRY_MAYFAIL retries as long as the reclaim makes a forward
progress and backs of when we are out of memory for the requested size.
Therefore we do not need to enforce__GFP_NORETRY for !costly orders just
to silent the oom killer anymore.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/util.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/mm/util.c b/mm/util.c
index 6520f2d4a226..ee250e2cde34 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -339,9 +339,9 @@ EXPORT_SYMBOL(vm_mmap);
  * Uses kmalloc to get the memory but if the allocation fails then falls back
  * to the vmalloc allocator. Use kvfree for freeing the memory.
  *
- * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported. __GFP_RETRY_MAYFAIL
- * is supported only for large (>32kB) allocations, and it should be used only if
- * kmalloc is preferable to the vmalloc fallback, due to visible performance drawbacks.
+ * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported.
+ * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
+ * preferable to the vmalloc fallback, due to visible performance drawbacks.
  *
  * Any use of gfp flags outside of GFP_KERNEL should be consulted with mm people.
  */
@@ -366,13 +366,7 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
 	if (size > PAGE_SIZE) {
 		kmalloc_flags |= __GFP_NOWARN;
 
-		/*
-		 * We have to override __GFP_RETRY_MAYFAIL by __GFP_NORETRY for !costly
-		 * requests because there is no other way to tell the allocator
-		 * that we want to fail rather than retry endlessly.
-		 */
-		if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL) ||
-				(size <= PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
+		if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
 			kmalloc_flags |= __GFP_NORETRY;
 	}
 
-- 
2.11.0

  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-23  8:53 [PATCH 0/6] mm: give __GFP_REPEAT a better semantic Michal Hocko
2017-06-23  8:53 ` [PATCH 1/6] MIPS: do not use __GFP_REPEAT for order-0 request Michal Hocko
2017-06-23 10:27   ` Ralf Baechle
2017-06-26  9:36   ` Vlastimil Babka
2017-06-23  8:53 ` [PATCH 2/6] mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic Michal Hocko
2017-06-26 11:45   ` Vlastimil Babka
2017-06-26 12:14     ` Michal Hocko
2017-06-26 12:17       ` Vlastimil Babka
2017-06-26 12:38         ` Michal Hocko
2017-06-26 12:42           ` Michal Hocko
2017-06-26 11:53   ` Vlastimil Babka
2017-06-23  8:53 ` [PATCH 3/6] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL Michal Hocko
2017-06-27  8:49   ` Michal Hocko
2017-06-27 13:47     ` Christoph Hellwig
2017-06-27 14:06       ` Michal Hocko
2017-06-28  4:12         ` Darrick J. Wong
2017-06-23  8:53 ` Michal Hocko [this message]
2017-06-26 12:00   ` [PATCH 4/6] mm: kvmalloc support __GFP_RETRY_MAYFAIL for all sizes Vlastimil Babka
2017-06-26 12:18     ` Michal Hocko
2017-06-23  8:53 ` [PATCH 5/6] drm/i915: use __GFP_RETRY_MAYFAIL Michal Hocko
2017-06-23  8:53 ` [PATCH 6/6] mm, migration: do not trigger OOM killer when migrating memory Michal Hocko
2017-06-23 20:43   ` Andrew Morton
2017-06-26  5:28     ` Michal Hocko
2017-06-26 12:13   ` Vlastimil Babka

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