Re: mm/percpu.c: use smarter memory allocation for struct pcpu_alloc_info (crisv32 hang)

From: Guenter Roeck <linux@roeck-us.net>
To: Tejun Heo <tj@kernel.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>,
	Christoph Lameter <cl@linux.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Mikael Starvik <starvik@axis.com>,
	Jesper Nilsson <jesper.nilsson@axis.com>,
	linux-cris-kernel@axis.com
Subject: Re: mm/percpu.c: use smarter memory allocation for struct pcpu_alloc_info (crisv32 hang)
Date: Mon, 27 Nov 2017 13:11:14 -0800	[thread overview]
Message-ID: <20171127211114.GA23806@roeck-us.net> (raw)
In-Reply-To: <20171127205421.GR983427@devbig577.frc2.facebook.com>

On Mon, Nov 27, 2017 at 12:54:21PM -0800, Tejun Heo wrote:
> Hello, Nicolas.
> 
> On Mon, Nov 27, 2017 at 03:51:04PM -0500, Nicolas Pitre wrote:
> > Subject: percpu: hack to let the CRIS architecture to boot until they clean up
> > 
> > Commit 438a506180 ("percpu: don't forget to free the temporary struct 
> > pcpu_alloc_info") uncovered a problem on the CRIS architecture where
> > the bootmem allocator is initialized with virtual addresses. Given it 
> > has:
> > 
> >     #define __va(x) ((void *)((unsigned long)(x) | 0x80000000))
> > 
> > then things just work out because the end result is the same whether you
> > give this a physical or a virtual address.
> > 
> > Untill you call memblock_free_early(__pa(address)) that is, because
> > values from __pa() don't match with the virtual addresses stuffed in the
> > bootmem allocator anymore.
> > 
> > Avoid freeing the temporary pcpu_alloc_info memory on that architecture
> > until they fix things up to let the kernel boot like it did before.
> > 
> > Signed-off-by: Nicolas Pitre <nico@linaro.org>
> 
> This totally works for me.  Replaced the revert with this one.
> 
Same here.

Thanks,
Guenter

> Thanks!
> 
> -- 
> tejun