Re: [PATCH 2/2][v2] powerpc: Make the CMM memory hotplug aware

From: Gerald Schaefer
Date: Thu Oct 08 2009 - 08:14:07 EST


Hi,

I am currently working on the s390 port for the cmm + hotplug
patch, and I'm a little confused about the memory allocation
policy, see below. Is it correct that the balloon cannot grow
into ZONE_MOVABLE, while the pages for the balloon page list
can?

Robert Jennings wrote:
@@ -110,6 +125,9 @@ static long cmm_alloc_pages(long nr)
cmm_dbg("Begin request for %ld pages\n", nr);

while (nr) {
+ if (atomic_read(&hotplug_active))
+ break;
+
addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
__GFP_NORETRY | __GFP_NOMEMALLOC);
if (!addr)
@@ -119,8 +137,10 @@ static long cmm_alloc_pages(long nr)
if (!pa || pa->index >= CMM_NR_PAGES) {
/* Need a new page for the page list. */
spin_unlock(&cmm_lock);
- npa = (struct cmm_page_array *)__get_free_page(GFP_NOIO | __GFP_NOWARN |
- __GFP_NORETRY | __GFP_NOMEMALLOC);
+ npa = (struct cmm_page_array *)__get_free_page(
+ GFP_NOIO | __GFP_NOWARN |
+ __GFP_NORETRY | __GFP_NOMEMALLOC |
+ __GFP_MOVABLE);
if (!npa) {
pr_info("%s: Can not allocate new page list\n", __func__);
free_page(addr);

Why is the __GFP_MOVABLE added here, for the page list alloc, and not
above for the balloon page alloc?

--
Regards,
Gerald

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