linux-kernel - Re: [PATCH] nommu: fix kobjsize() for SLOB and SLUB

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Date:	Sun, 1 Jun 2008 12:13:02 +0300 (EEST)
From:	Pekka J Enberg <penberg@...helsinki.fi>
To:	Paul Mundt <lethal@...ux-sh.org>
cc:	David Howells <dhowells@...hat.com>,
	Christoph Lameter <clameter@....com>,
	LKML <linux-kernel@...r.kernel.org>, cooloney@...nel.org,
	akpm@...ux-foundation.org, mpm@...enic.com
Subject: Re: [PATCH] nommu: fix kobjsize() for SLOB and SLUB

Hi Paul,

On Sun, 1 Jun 2008, Paul Mundt wrote:
> This still needs to be virt_to_head_page() I think.
> 
> I don't have my nommu boards at home, so I'll test at the office tomorow
> morning and let you know.

I was about to send a patch that fixes some of the kobjsize() abuses to 
use ksize() but then I realized that what we probably should do is 
something like this instead.

I mean, assuming the BUG_ON bits are bogus, then we should always pass the 
pointer to the allocator. I audited most of the callers and they all seem 
to be really just using kmalloc() for allocation anyway.

What do you think?

		Pekka

diff --git a/mm/nommu.c b/mm/nommu.c
index dca93fc..fc1ff52 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -103,22 +103,20 @@ EXPORT_SYMBOL(vmtruncate);
  */
 unsigned int kobjsize(const void *objp)
 {
-	struct page *page;
-
 	/*
 	 * If the object we have should not have ksize performed on it,
 	 * return size of 0
 	 */
-	if (!objp || (unsigned long)objp >= memory_end || !((page = virt_to_page(objp))))
+	if (!objp)
 		return 0;
 
-	if (PageSlab(page))
-		return ksize(objp);
+	if ((unsigned long)objp >= memory_end)
+		return 0;
 
-	BUG_ON(page->index < 0);
-	BUG_ON(page->index >= MAX_ORDER);
+	if (!virt_to_page(objp))
+		return 0;
 
-	return (PAGE_SIZE << page->index);
+	return ksize(objp);
 }
 
 /*
--
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