linux-kernel - Re: [RFC][PATCH] kmemdup_from

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Message-Id: <20090306164445.7BE4.A69D9226@jp.fujitsu.com>
Date:	Fri,  6 Mar 2009 17:03:29 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Davi Arnaut <davi.arnaut@...il.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	Americo Wang <xiyou.wangcong@...il.com>,
	Li Zefan <lizf@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [RFC][PATCH] kmemdup_from_user(): introduce

(cc to Davi Arnaut)

> > > /**
> > >+ * kmemdup_from_user - duplicate memory region from user space
> > >+ *
> > >+ * @src: source address in user space
> > >+ * @len: number of bytes to copy
> > >+ * @gfp: GFP mask to use
> > >+ */
> > >+void *kmemdup_from_user(const void __user *src, size_t len, gfp_t gfp)
> > >+{
> > >+	void *p;
> > >+
> > >+	p = kmalloc_track_caller(len, gfp);
> > 
> > 
> > Well, you use kmalloc_track_caller, instead of kmalloc as you showed
> > above. :) Why don't you mention this?
> 
> kmalloc() wrapper function must use kmalloc_track_caller().

I find another kmalloc() usage in the same file.
Davi, Can you agree following patch?


==
Subject: [PATCH] Don't use kmalloc() in strndup_user(). instead, use kmalloc_track_caller().

kmalloc() wrapper function should use kmalloc_track_caller() instead
kmalloc().

slab.h talk about the reason. 

/*
 * kmalloc_track_caller is a special version of kmalloc that records the
 * calling function of the routine calling it for slab leak tracking instead
 * of just the calling function (confusing, eh?).
 * It's useful when the call to kmalloc comes from a widely-used standard
 * allocator where we care about the real place the memory allocation
 * request comes from.
 */


Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
 mm/util.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/util.c b/mm/util.c
index 37eaccd..202da19 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -167,7 +167,7 @@ char *strndup_user(const char __user *s, long n)
 	if (length > n)
 		return ERR_PTR(-EINVAL);
 
-	p = kmalloc(length, GFP_KERNEL);
+	p = kmalloc_track_caller(length, GFP_KERNEL);
 
 	if (!p)
 		return ERR_PTR(-ENOMEM);
-- 
1.6.1.2



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