linux-kernel - [PATCH] Create initial stack independent of PAGE

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Message-ID: <31586.1265953455@neuling.org>
Date:	Fri, 12 Feb 2010 16:44:15 +1100
From:	Michael Neuling <mikey@...ling.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Helge Deller <deller@....de>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Americo Wang <xiyou.wangcong@...il.com>,
	Anton Blanchard <anton@...ba.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] Create initial stack independent of PAGE_SIZE

Currently we create the initial stack based on the PAGE_SIZE.  This is
unnecessary.  

This creates this initial stack independent of the PAGE_SIZE.

It also bumps up the number of 4k pages allocated from 20 to 32, to
align with 64K page systems.

Signed-off-by: Michael Neuling <mikey@...ling.org>
---
This is the second half of my original patch. This can be targeted for
2.6.34 as it's just a cleanup.

Tested on PPC64 with 4k and 64k pages.

 fs/exec.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Index: linux-2.6-ozlabs/fs/exec.c
===================================================================
--- linux-2.6-ozlabs.orig/fs/exec.c
+++ linux-2.6-ozlabs/fs/exec.c
@@ -554,8 +554,6 @@ static int shift_arg_pages(struct vm_are
 	return 0;
 }
 
-#define EXTRA_STACK_VM_PAGES	20	/* random */
-
 /*
  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
  * the stack is optionally relocated, and some extra space is added.
@@ -630,7 +628,7 @@ int setup_arg_pages(struct linux_binprm 
 			goto out_unlock;
 	}
 
-	stack_expand = EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 	stack_size = vma->vm_end - vma->vm_start;
 	/*
 	 * Align this down to a page boundary as expand_stack
--
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