[RFC/PATCH] zcache2 on PPC64 (Was: [RFC] mm: add support for zsmalloc and zcache)

[RFC/PATCH] zcache2 on PPC64 (Was: [RFC] mm: add support for zsmalloc and zcache)

[Dan Magenheimer]

Attached patch applies to staging-next and I _think_ should
fix the reported problem where zbud in zcache2 does not
work on a PPC64 with PAGE_SIZE!=12.  I do not have a machine
to test this so testing by others would be appreciated.

Ideally there should also be a BUILD_BUG_ON to ensure
PAGE_SHIFT * 2 + 2 doesn't exceed BITS_PER_LONG, but
let's see if this fixes the problem first.

Apologies if there are line breaks... I can't send this from
a linux mailer right now.  If it is broken, let me know,
and I will re-post tomorrow... though it should be easy
to apply manually for test purposes.

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>

diff --git a/drivers/staging/ramster/zbud.c b/drivers/staging/ramster/zbud.c
index a7c4361..6921af3 100644
--- a/drivers/staging/ramster/zbud.c
+++ b/drivers/staging/ramster/zbud.c
@@ -103,8 +103,8 @@ struct zbudpage {
 		struct {
 			unsigned long space_for_flags;
 			struct {
-				unsigned zbud0_size:12;
-				unsigned zbud1_size:12;
+				unsigned zbud0_size:PAGE_SHIFT;
+				unsigned zbud1_size:PAGE_SHIFT;
 				unsigned unevictable:2;
 			};
 			struct list_head budlist;

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Re: [RFC/PATCH] zcache2 on PPC64 (Was: [RFC] mm: add support for zsmalloc and zcache)

[Mel Gorman]

On Tue, Sep 25, 2012 at 04:31:01PM -0700, Dan Magenheimer wrote:
> Attached patch applies to staging-next and I _think_ should
> fix the reported problem where zbud in zcache2 does not
> work on a PPC64 with PAGE_SIZE!=12.  I do not have a machine
> to test this so testing by others would be appreciated.
> 

Seth, can you verify?

-- 
Mel Gorman
SUSE Labs

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Re: [RFC/PATCH] zcache2 on PPC64 (Was: [RFC] mm: add support for zsmalloc and zcache)

[Seth Jennings]

On 09/28/2012 08:31 AM, Mel Gorman wrote:
> On Tue, Sep 25, 2012 at 04:31:01PM -0700, Dan Magenheimer wrote:
>> Attached patch applies to staging-next and I _think_ should
>> fix the reported problem where zbud in zcache2 does not
>> work on a PPC64 with PAGE_SIZE!=12.  I do not have a machine
>> to test this so testing by others would be appreciated.
>>
> 
> Seth, can you verify?

Yes, this patch does prevent the crash on PPC64.

Seth

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