linux-kernel - Re: mmotm 2009-01-12-16-53 uploaded

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Date:	Tue, 13 Jan 2009 18:13:17 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org,
	"linux-mm@...ck.org" <linux-mm@...ck.org>, yinghan@...gle.com,
	mikew@...gle.com, hugh@...itas.com
Subject: Re: mmotm 2009-01-12-16-53 uploaded

On Mon, 12 Jan 2009 16:53:43 -0800
akpm@...ux-foundation.org wrote:

> The mm-of-the-moment snapshot 2009-01-12-16-53 has been uploaded to
> 
>    http://userweb.kernel.org/~akpm/mmotm/
> 
> and will soon be available at
> 
>    git://git.zen-sources.org/zen/mmotm.git
> 

After rtc compile fix, the kernel boots.

But with CONFIG_DEBUG_VM, I saw BUG_ON() at 

fork() -> ...
	-> copy_page_range() ...
		-> copy_one_pte()
			->page_dup_rmap()
				-> __page_check_anon_rmap().

BUG_ON(page->index != linear_page_index(vma, address)); 
fires. (from above, the page is ANON.)

It seems page->index == 0x7FFFFFFE here and the page seems to be
the highest address of stack.

This is caused by
 fs-execc-fix-value-of-vma-vm_pgoff-for-the-stack-vma-of-32-bit-processes.patch 


This is a fix.
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

pgoff is *not* vma->vm_start >> PAGE_SHIFT.
And no adjustment is necessary (when it maps the same start
before/after adjust vma.)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
Index: mmotm-2.6.29-Jan12/fs/exec.c
===================================================================
--- mmotm-2.6.29-Jan12.orig/fs/exec.c
+++ mmotm-2.6.29-Jan12/fs/exec.c
@@ -509,7 +509,7 @@ static int shift_arg_pages(struct vm_are
 	unsigned long length = old_end - old_start;
 	unsigned long new_start = old_start - shift;
 	unsigned long new_end = old_end - shift;
-	unsigned long new_pgoff = new_start >> PAGE_SHIFT;
+	unsigned long new_pgoff = vma->vm_pgoff;
 	struct mmu_gather *tlb;
 
 	BUG_ON(new_start > new_end);

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