Re: Oops in a driver while using SLUB as a SLAB allocator

From: Hugh Dickins <hugh@veritas.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Nicolas Ferre <nicolas.ferre@rfo.atmel.com>,
	ARM Linux Mailing List  <linux-arm-kernel@lists.arm.linux.org.uk>,
	Linux Kernel list <linux-kernel@vger.kernel.org>,
	Marc Pignat <marc.pignat@hevs.ch>,
	Andrew Victor <andrew@sanpeople.com>,
	Pierre Ossman <drzeus@drzeus.cx>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Russell King <rmk@arm.linux.org.uk>
Subject: Re: Oops in a driver while using SLUB as a SLAB allocator
Date: Fri, 22 Jun 2007 05:26:33 +0100 (BST)	[thread overview]
Message-ID: <Pine.LNX.4.64.0706220513140.8870@blonde.wat.veritas.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0706211759550.11554@schroedinger.engr.sgi.com>

On Thu, 21 Jun 2007, Christoph Lameter wrote:
> On Thu, 21 Jun 2007, Hugh Dickins wrote:
> 
> > > The oops seems to occur after a page unmapping using dma_unmap_page() followed
> > > by a flush_dcache_page() (in at91mci_post_dma_read()).
> 
> Was the page allocated using slab calls?

You've found yes (in the ARM case).

> Well one may be better off allocating pages using the page allocator 
> instead of the slab allocator. I removed these things from i386 but I did 
> not check ARM.

They may or may not be: I think that's a matter to discuss with rmk.

You keep on forcing the outside world to revolve around your needs
within slub.c: that is a good way to keep slub lean, and may be
justified; but it's at least questionable to be enforcing such
restrictions years after people have grown accustomed to more
freedom from their slabs.

Hugh