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authorMel Gorman <mgorman@techsingularity.net>2015-11-06 16:28:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-06 17:50:42 -0800
commitdd56b046426760aa0c852ad6e4b6b07891222d65 (patch)
tree7012f11f80b22d4df3372305062fcefb899d5c50 /mm/internal.h
parent97a16fc82a7c5b0cfce95c05dfb9561e306ca1b1 (diff)
downloadop-kernel-dev-dd56b046426760aa0c852ad6e4b6b07891222d65.zip
op-kernel-dev-dd56b046426760aa0c852ad6e4b6b07891222d65.tar.gz
mm: page_alloc: hide some GFP internals and document the bits and flag combinations
Andrew stated the following We have quite a history of remote parts of the kernel using weird/wrong/inexplicable combinations of __GFP_ flags. I tend to think that this is because we didn't adequately explain the interface. And I don't think that gfp.h really improved much in this area as a result of this patchset. Could you go through it some time and decide if we've adequately documented all this stuff? This patches first moves some GFP flag combinations that are part of the MM internals to mm/internal.h. The rest of the patch documents the __GFP_FOO bits under various headings and then documents the flag combinations. It will not help callers that are brain damaged but the clarity might motivate some fixes and avoid future mistakes. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/internal.h')
-rw-r--r--mm/internal.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/mm/internal.h b/mm/internal.h
index ff0f1ad..5b7841f6 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -14,6 +14,25 @@
#include <linux/fs.h>
#include <linux/mm.h>
+/*
+ * The set of flags that only affect watermark checking and reclaim
+ * behaviour. This is used by the MM to obey the caller constraints
+ * about IO, FS and watermark checking while ignoring placement
+ * hints such as HIGHMEM usage.
+ */
+#define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\
+ __GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
+ __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC)
+
+/* The GFP flags allowed during early boot */
+#define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS))
+
+/* Control allocation cpuset and node placement constraints */
+#define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE)
+
+/* Do not use these with a slab allocator */
+#define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK)
+
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
unsigned long floor, unsigned long ceiling);
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