On Thursday October 1, rientjes@google.com wrote:

On Thu, 1 Oct 2009, Suresh Jayaraman wrote:

quoted

From: Peter Zijlstra <redacted> 

Expose the gfp to alloc_flags mapping, so we can use it in other parts
of the vm.

Signed-off-by: Peter Zijlstra <redacted>
Signed-off-by: Suresh Jayaraman <redacted>

Nack, these flags are internal to the page allocator and exporting them to 
generic VM code is unnecessary.

The only bit you actually use in your patchset is ALLOC_NO_WATERMARKS to 
determine whether a particular allocation can use memory reserves.  I'd 
suggest adding a bool function that returns whether the current context is 
given access to reserves including your new __GFP_MEMALLOC flag and 
exporting that instead.

That sounds like a very appropriate suggestion, thanks.

So something like this?
Then change every occurrence of
+		if (!(gfp_to_alloc_flags(gfpflags) & ALLOC_NO_WATERMARKS))
to
+		if (!(gfp_has_no_watermarks(gfpflags)))

??

Thanks,
NeilBrown

diff --git a/mm/internal.h b/mm/internal.h
index 22ec8d2..7ff78d6 100644
--- a/mm/internal.h
+++ b/mm/internal.h

@@ -195,6 +195,8 @@ static inline struct page *mem_map_next(struct page *iter,
 #define __paginginit __init
 #endif
 
+int gfp_has_no_watermarks(gfp_t gfp_mask);
+
 /* Memory initialisation debug and verification */
 enum mminit_level {
 	MMINIT_WARNING,

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bf72055..4b4292a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -1782,6 +1782,11 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
 	return alloc_flags;
 }
 
+int gfp_has_no_watermarks(gfp_t gfp_mask)
+{
+	return (gfp_to_alloc_flags(gfp_mask) & ALLOC_NO_WATERMARKS);
+}
+
 static inline struct page *
 __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	struct zonelist *zonelist, enum zone_type high_zoneidx,

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