From: Christoph Lameter <cl@linux.com>
To: Glauber Costa <glommer@parallels.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
linux-mm@kvack.org, Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Any reason to use put_page in slub.c?
Date: Wed, 1 Aug 2012 13:10:42 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1208011307450.4606@router.home> (raw)
In-Reply-To: <50192453.9080706@parallels.com>
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
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next prev parent reply other threads:[~2012-08-01 18:10 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-27 12:19 Any reason to use put_page in slub.c? Glauber Costa
2012-07-27 15:55 ` Christoph Lameter
2012-07-30 7:53 ` Glauber Costa
2012-07-30 19:23 ` Christoph Lameter
2012-07-31 8:25 ` Glauber Costa
2012-07-31 14:09 ` Christoph Lameter
2012-07-31 14:09 ` Glauber Costa
2012-07-31 14:17 ` Christoph Lameter
2012-07-31 14:18 ` Glauber Costa
2012-07-31 14:31 ` Christoph Lameter
2012-07-31 14:52 ` James Bottomley
2012-08-01 12:42 ` Glauber Costa
2012-08-01 18:10 ` Christoph Lameter [this message]
2012-08-02 7:55 ` Glauber Costa
2012-08-02 8:07 ` James Bottomley
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