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Date: Tue, 11 May 2004 17:23:25 -0700
From: Andrew Morton <akpm@osdl.org>
To: edwardsg@sgi.com (Greg Edwards)
Cc: linux-kernel@vger.kernel.org, thockin@sun.com
Subject: Re: [PATCH] calculate NGROUPS_PER_BLOCK from PAGE_SIZE
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References: <20040511174944.GA26708@sgi.com>
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edwardsg@sgi.com (Greg Edwards) wrote:
>
> On ia64, EXEC_PAGESIZE (max page size) is 65536, but the default page
> size is 16k.  This results in NGROUPS_PER_BLOCK in include/linux/sched.h
> being calculated incorrectly when the page size is anything other than
> 64k.  For example, on a 16k page size kernel, a setgroups() call with a
> gidsetsize of 65536 will end up walking over memory since only 1/4 of
> the needed pages were allocated for the blocks[] array in the group_info
> struct.
> 
> Patch below calculates NGROUPS_PER_BLOCK from PAGE_SIZE instead.

yep, thanks.