From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx155.postini.com [74.125.245.155]) by kanga.kvack.org (Postfix) with SMTP id 1B8D46B006E for ; Wed, 1 Aug 2012 14:10:45 -0400 (EDT) Date: Wed, 1 Aug 2012 13:10:42 -0500 (CDT) From: Christoph Lameter Subject: Re: Any reason to use put_page in slub.c? In-Reply-To: <50192453.9080706@parallels.com> Message-ID: References: <1343391586-18837-1-git-send-email-glommer@parallels.com> <50163D94.5050607@parallels.com> <5017968C.6050301@parallels.com> <5017E72D.2060303@parallels.com> <5017E929.70602@parallels.com> <1343746344.8473.4.camel@dabdike.int.hansenpartnership.com> <50192453.9080706@parallels.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: James Bottomley , linux-mm@kvack.org, Pekka Enberg , David Rientjes , Andrew Morton On Wed, 1 Aug 2012, Glauber Costa wrote: > I've audited all users of get_page() in the drivers/ directory for > patterns like this. In general, they kmalloc something like a table of > entries, and then get_page() the entries. The entries are either user > pages, pages allocated by the page allocator, or physical addresses > through their pfn (in 2 cases from the vga ones...) > > I took a look about some other instances where virt_to_page occurs > together with kmalloc as well, and they all seem to fall in the same > category. The case that was notorious in the past was a scsi control structure allocated from slab that was then written to the device via DMA. And it was not on x86 but some esoteric platform (powerpc?), A reference to the discussion of this issue in 2007: http://lkml.indiana.edu/hypermail/linux/kernel/0706.3/0424.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org