[Xen-devel] [PATCH] "lock cmpxch8b" and split locks

["Puthiyaparambil, Aravindh" <aravindh.puthiyaparambil@xxxxxxxxxx>]

I have been looking at the following bug
http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=252
That investigation is still underway. 

While looking at this problem I found that in "lock cmpxch8b
&page->count_info" occurring in "get_page( )", "&page->count_info" is on
a misaligned address. Furthermore the address of "page" is not modulo
64. So the "lock cmpxch8b" can happen across cache lines and lead to a
split lock. On systems which have multiple buses, the atomicity of such
a statement is not assured and can cause synchronization problems. 

I have attached a patch which solves this issue.

Does anyone know if there are other places where the "lock" prefix is
used with a cache misaligned address?
 
Signed off by Aravindh Puthiyaparambil
<aravindh.puthiyaparambil@xxxxxxxxxx>

Attachment: mm.patch
Description: mm.patch

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel