Re: [PATCH v2 10/10] thp: implement refcounting for huge zero page

From: Eric Dumazet
Date: Mon Sep 10 2012 - 10:57:58 EST

On Mon, 2012-09-10 at 17:44 +0300, Kirill A. Shutemov wrote:

> 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 :

zero_page = alloc_pages(GFP_TRANSHUGE | __GFP_ZERO, HPAGE_PMD_ORDER);
if (!zero_page)
return 0;
if (cmpxchg(&huge_zero_pfn, 0, page_to_pfn(zero_page))) {
goto retry;
atomic_set(&huge_zero_refcount, 2);

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