On Thu, 29 May 2014, Marcelo Tosatti wrote: > diff --git a/kernel/cpuset.c b/kernel/cpuset.c > index 3d54c41..3bbc23f 100644 > --- a/kernel/cpuset.c > +++ b/kernel/cpuset.c > @@ -2374,6 +2374,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) > * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set > * in alloc_flags. That logic and the checks below have the combined > * affect that: > + * gfp_zone(mask) < policy_zone - any node ok > * in_interrupt - any node ok (current task context irrelevant) > * GFP_ATOMIC - any node ok > * TIF_MEMDIE - any node ok > @@ -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 > might_sleep_if(!(gfp_mask & __GFP_HARDWALL)); > if (node_isset(node, current->mems_allowed)) > return 1; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5dba293..0fd6923 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2723,6 +2723,11 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > if (!memcg_kmem_newpage_charge(gfp_mask, &memcg, order)) > return NULL; > > +#ifdef CONFIG_NUMA > + if (!nodemask && gfp_zone(gfp_mask) < policy_zone) > + nodemask = &node_states[N_MEMORY]; > +#endif > + > retry_cpuset: > cpuset_mems_cookie = read_mems_allowed_begin(); > When I said that my point about mempolicies needs more thought, I wasn't expecting that there would be no discussion -- at least _something_ that would say why we don't care about the mempolicy case. The motivation here is identical for both cpusets and mempolicies. What is the significant difference between attaching a process to a cpuset without access to lowmem and a process doing set_mempolicy(MPOL_BIND) without access to lowmem? Is it because the process should know what it's doing if it asks for a mempolicy that doesn't include lowmem? If so, is the cpusets case different because the cpuset attacher isn't held to the same standard? I'd argue that an application may never know if it needs to allocate GFP_DMA32 or not since its a property of the hardware that its running on and my driver may need to access lowmem while yours may not. I may even configure CONFIG_ZONE_DMA=n and CONFIG_ZONE_DMA32=n because I know the _hardware_ requirements of my platforms. If there is no difference, then why are we allowing the exception for cpusets and not mempolicies? I really think you want to allow both cpusets and mempolicies. I'd like to hear Christoph's thoughts on it as well, though. Furthermore, I don't know why you're opposed to the comments that Andrew added here. In the first version of this patch, I suggested a comment and you referred to a kernel/cpuset.c comment. Nowhere in the above change to the page allocator would make anyone think of cpusets or what it is trying to do. Please comment the code accordingly so your intention is understood for everybody else who happens upon your code. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>