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From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Rik van Riel <riel@redhat.com>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Michal Hocko <mhocko@kernel.org>, Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] mm: page_alloc: Hide some GFP internals and document the bits and flag combinations -fix
Date: Fri, 2 Oct 2015 14:03:45 +0100	[thread overview]
Message-ID: <20151002130345.GS3068@techsingularity.net> (raw)
In-Reply-To: <560CF134.2060107@suse.cz>

This patch address minor comment nitpicks from Vlastimil. It is a fix for the
mmotm patch
mm-page_alloc-hide-some-GFP-internals-and-document-the-bit-and-flag-combinations.patch

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 include/linux/gfp.h | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 67654f08a28b..4ab8cfa0aa9f 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -110,17 +110,18 @@ struct vm_area_struct;
  *
  * __GFP_IO can start physical IO.
  *
- * __GFP_FS can call down to the low-level FS. Avoids the allocator
- *   recursing into the filesystem which might already be holding locks.
+ * __GFP_FS can call down to the low-level FS. Clearing the flag avoids the
+ *   allocator recursing into the filesystem which might already be holding
+ *   locks.
  *
  * __GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim.
  *   This flag can be cleared to avoid unnecessary delays when a fallback
  *   option is available.
  *
- * __GFP_KSWAPD_RECLAIM indicates that the caller wants kswapd when the low
- *   watermark is reached and have it reclaim pages until the high watermark
- *   is reached. A caller may wish to clear this flag when fallback options
- *   are available and the reclaim is likely to disrupt the system. The
+ * __GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when
+ *   the low watermark is reached and have it reclaim pages until the high
+ *   watermark is reached. A caller may wish to clear this flag when fallback
+ *   options are available and the reclaim is likely to disrupt the system. The
  *   canonical example is THP allocation where a fallback is cheap but
  *   reclaim/compaction may cause indirect stalls.
  *
@@ -208,11 +209,6 @@ struct vm_area_struct;
  *   for buffers that are mapped to userspace (e.g. graphics) that hardware
  *   still must DMA to. cpuset limits are enforced for these allocations.
  *
- * GFP_HIGHUSER is for userspace allocations that may be mapped to userspace,
- *   do not need to be directly accessible by the kernel but that cannot
- *   move once in use. An example may be a hardware allocation that maps
- *   data directly into userspace but has no addressing limitations.
- *
  * GFP_DMA exists for historical reasons and should be avoided where possible.
  *   The flags indicates that the caller requires that the lowest zone be
  *   used (ZONE_DMA or 16M on x86-64). Ideally, this would be removed but
@@ -223,6 +219,11 @@ struct vm_area_struct;
  * GFP_DMA32 is similar to GFP_DMA except that the caller requires a 32-bit
  *   address.
  *
+ * GFP_HIGHUSER is for userspace allocations that may be mapped to userspace,
+ *   do not need to be directly accessible by the kernel but that cannot
+ *   move once in use. An example may be a hardware allocation that maps
+ *   data directly into userspace but has no addressing limitations.
+ *
  * GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not
  *   need direct access to but can use kmap() when access is required. They
  *   are expected to be movable via page reclaim or page migration. Typically,

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  reply	other threads:[~2015-10-02 13:03 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-21 10:52 [PATCH 00/10] Remove zonelist cache and high-order watermark checking v4 Mel Gorman
2015-09-21 10:52 ` [PATCH 01/10] mm, page_alloc: Remove unnecessary parameter from zone_watermark_ok_safe Mel Gorman
2015-09-24 20:01   ` Johannes Weiner
2015-09-21 10:52 ` [PATCH 02/10] mm, page_alloc: Remove unnecessary recalculations for dirty zone balancing Mel Gorman
2015-09-24 20:05   ` Johannes Weiner
2015-09-21 10:52 ` [PATCH 03/10] mm, page_alloc: Remove unnecessary taking of a seqlock when cpusets are disabled Mel Gorman
2015-09-24 20:06   ` Johannes Weiner
2015-09-30 22:22   ` David Rientjes
2015-10-01  7:35     ` Vlastimil Babka
2015-09-21 10:52 ` [PATCH 04/10] mm, page_alloc: Use masks and shifts when converting GFP flags to migrate types Mel Gorman
2015-09-24 20:34   ` Johannes Weiner
2015-09-25 12:50     ` Mel Gorman
2015-09-25 13:56       ` Johannes Weiner
2015-09-21 10:52 ` [PATCH 05/10] mm, page_alloc: Distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd Mel Gorman
2015-09-24 13:51   ` Michal Hocko
2015-09-24 20:55   ` Johannes Weiner
2015-09-25 12:51     ` Mel Gorman
2015-09-25 19:01       ` Johannes Weiner
2015-09-29 13:35         ` Mel Gorman
2015-09-30 12:26           ` Vlastimil Babka
2015-09-30 13:17             ` Mel Gorman
2015-10-01  3:04             ` Drokin, Oleg
2015-10-02 12:30               ` Mel Gorman
2015-09-21 10:52 ` [PATCH 06/10] mm, page_alloc: Rename __GFP_WAIT to __GFP_RECLAIM Mel Gorman
2015-09-25 19:03   ` Johannes Weiner
2015-09-28 23:55   ` Andrew Morton
2015-09-29 13:37     ` Mel Gorman
2015-10-01  8:39       ` Vlastimil Babka
2015-10-02 13:03         ` Mel Gorman [this message]
2015-10-01 14:06       ` Michal Hocko
2015-09-30 22:25   ` David Rientjes
2015-09-21 10:52 ` [PATCH 07/10] mm, page_alloc: Delete the zonelist_cache Mel Gorman
2015-09-25 19:09   ` Johannes Weiner
2015-09-21 10:52 ` [PATCH 08/10] mm, page_alloc: Remove MIGRATE_RESERVE Mel Gorman
2015-09-21 10:52 ` [PATCH 09/10] mm, page_alloc: Reserve pageblocks for high-order atomic allocations on demand Mel Gorman
2015-09-24 13:50   ` Michal Hocko
2015-09-25 19:22   ` Johannes Weiner
2015-09-29 21:01   ` Andrew Morton
2015-09-30  8:27     ` Mel Gorman
2015-09-30 14:02       ` Vlastimil Babka
2015-09-21 12:03 ` [PATCH 10/10] mm, page_alloc: Only enforce watermarks for order-0 allocations Mel Gorman
2015-09-25 19:32   ` Johannes Weiner
2015-09-29 21:05   ` Andrew Morton
2015-09-30  8:46     ` Mel Gorman
2015-09-30 14:17       ` Vlastimil Babka
2015-09-30 15:12         ` Mel Gorman
2015-09-30 20:37           ` Andrew Morton
2015-09-30 14:11   ` Vlastimil Babka

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