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Date: Sun, 21 Apr 2002 09:47:52 +1000
From: Anton Blanchard <anton@samba.org>
To: Mel <mel@csn.ul.ie>
Cc: linux-kernel@vger.kernel.org
Subject: Re: vmalloc comments patch
Message-ID: <20020420234752.GA26727@krispykreme>
In-Reply-To: <Pine.LNX.4.44.0204201740480.3995-100000@skynet>
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Hi,

> + * To give a safety margin, the linear address starts about 8MB after the end
> + * of physical memory at VMALLOC_START. This is to try and catch memory
> + * overruns.

Thats architecture dependent. On ppc64 for example the kernel text
starts at 0xC000000000000000 and the vmalloc region starts at
0xD000000000000000, 2^60 bits apart.

> +		/* The page table is unlocked because we don't need to traverse
> +		 * the page tables while a page is been allocated. As
> +		 * alloc_page could block for a long time, let go the lock
> +		 */
>  		spin_unlock(&init_mm.page_table_lock);
>  		page = alloc_page(gfp_mask);
>  		spin_lock(&init_mm.page_table_lock);

Since alloc_page can sleep we must drop the spinlock.

Anton
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