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From: Andi Kleen <andi@firstfloor.org>
To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Subject: Re: [PATCH 8/10] memory-hotplug : remove page table of x86_64
 architecture
References: <506E43E0.70507@jp.fujitsu.com> <506E4799.30407@jp.fujitsu.com>
Date: Sun, 07 Oct 2012 21:37:00 -0700
In-Reply-To: <506E4799.30407@jp.fujitsu.com> (Yasuaki Ishimatsu's message of
 "Fri, 5 Oct 2012 11:36:09 +0900")
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Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> writes:
> +			}
> +
> +			/*
> +			 * We use 2M page, but we need to remove part of them,
> +			 * so split 2M page to 4K page.
> +			 */
> +			pte = alloc_low_page(&pte_phys);

What happens when the allocation fails?

alloc_low_page seems to be buggy there too, it would __pa a NULL 
pointer.

> +		if (pud_large(*pud)) {
> +			if ((addr & ~PUD_MASK) == 0 && next <= end) {
> +				set_pud(pud, __pud(0));
> +				pages++;
> +				continue;
> +			}
> +
> +			/*
> +			 * We use 1G page, but we need to remove part of them,
> +			 * so split 1G page to 2M page.
> +			 */
> +			pmd = alloc_low_page(&pmd_phys);

Same here

> +			__split_large_page((pte_t *)pud, addr, (pte_t *)pmd);
> +
> +			spin_lock(&init_mm.page_table_lock);
> +			pud_populate(&init_mm, pud, __va(pmd_phys));
> +			spin_unlock(&init_mm.page_table_lock);
> +		}
> +
> +		pmd = map_low_page(pmd_offset(pud, 0));
> +		phys_pmd_remove(pmd, addr, end);
> +		unmap_low_page(pmd);
> +		__flush_tlb_all();
> +	}
> +	__flush_tlb_all();

This doesn't flush the other CPUs doesn't it?

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only