On Thu, 29 May 2014 15:43:03 -0300 Marcelo Tosatti <mtosa...@redhat.com> wrote:
>
> Zone specific allocations, such as GFP_DMA32, should not be restricted
> to cpusets allowed node list: the zones which such allocations demand
> might be contained in particular nodes outside the cpuset node list.
>
> Necessary for the following usecase:
> - driver which requires zone specific memory (such as KVM, which
> requires root pagetable at paddr < 4GB).
> - user wants to limit allocations of application to nodeX, and nodeX has
> no memory < 4GB.
>
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -2392,6 +2393,10 @@ int __cpuset_node_allowed_softwall(int node, gfp_t
> gfp_mask)
>
> if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
> return 1;
> +#ifdef CONFIG_NUMA
> + if (gfp_zone(gfp_mask) < policy_zone)
> + return 1;
> +#endif
It's not very obvious why this code is doing what it does, so I'm
thinking a comment is needed. And that changelog text looks good, so
---
a/kernel/cpuset.c~page_alloc-skip-cpuset-enforcement-for-lower-zone-allocations-v4-fix
+++ a/kernel/cpuset.c
@@ -2388,6 +2388,11 @@ int __cpuset_node_allowed_softwall(int n
if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
return 1;
#ifdef CONFIG_NUMA
+ /*
+ * Zone specific allocations such as GFP_DMA32 should not be restricted
+ * to cpusets allowed node list: the zones which such allocations
+ * demand be contained in particular nodes outside the cpuset node list
+ */
if (gfp_zone(gfp_mask) < policy_zone)
return 1;
#endif
---
a/mm/page_alloc.c~page_alloc-skip-cpuset-enforcement-for-lower-zone-allocations-v4-fix
+++ a/mm/page_alloc.c
@@ -2742,6 +2742,11 @@ retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
#ifdef CONFIG_NUMA
+ /*
+ * Zone specific allocations such as GFP_DMA32 should not be restricted
+ * to cpusets allowed node list: the zones which such allocations
+ * demand be contained in particular nodes outside the cpuset node list
+ */
if (gfp_zone(gfp_mask) < policy_zone)
nodemask = &node_states[N_ONLINE];
#endif
However perhaps it would be nicer to do
#ifdef CONFIG_NUMA
/*
* Zone specific allocations such as GFP_DMA32 should not be restricted to
* cpusets allowed node list: the zones which such allocations demand be
* contained in particular nodes outside the cpuset node list
*/
static inline bool i_cant_think_of_a_name(gfp_t mask)
{
return gfp_zone(gfp_mask) < policy_zone;
}
#else
static inline bool i_cant_think_of_a_name(gfp_t mask)
{
return false;
}
#endif
This encapsulates it all in a single place and zaps those ifdefs?
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