Re: [PATCH v2 10/10] thp: implement refcounting for huge zero page
From: Kirill A. Shutemov <hidden>
Date: 2012-09-10 15:07:23
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On Mon, Sep 10, 2012 at 04:57:59PM +0200, Eric Dumazet wrote:
On Mon, 2012-09-10 at 17:44 +0300, Kirill A. Shutemov wrote:quoted
Yes, disabling preemption before alloc_pages() and enabling after atomic_set() looks reasonable. Thanks.In fact, as alloc_pages(GFP_TRANSHUGE | __GFP_ZERO, HPAGE_PMD_ORDER); might sleep, it would be better to disable preemption after calling it :
Yeah, I've alread thought about that. :)
zero_page = alloc_pages(GFP_TRANSHUGE | __GFP_ZERO, HPAGE_PMD_ORDER);
if (!zero_page)
return 0;
preempt_disable();
if (cmpxchg(&huge_zero_pfn, 0, page_to_pfn(zero_page))) {
preempt_enable();
__free_page(zero_page);
goto retry;
}
atomic_set(&huge_zero_refcount, 2);
preempt_enable();
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