linux-kernel - Re: mm/percpu.c: use smarter memory allocation for struct pcpu_alloc

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Date:   Mon, 27 Nov 2017 13:11:14 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Tejun Heo <tj@...nel.org>
Cc:     Nicolas Pitre <nicolas.pitre@...aro.org>,
        Christoph Lameter <cl@...ux.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Mikael Starvik <starvik@...s.com>,
        Jesper Nilsson <jesper.nilsson@...s.com>,
        linux-cris-kernel@...s.com
Subject: Re: mm/percpu.c: use smarter memory allocation for struct
 pcpu_alloc_info (crisv32 hang)

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@...aro.org>
> 
> This totally works for me.  Replaced the revert with this one.
> 
Same here.

Thanks,
Guenter

> Thanks!
> 
> -- 
> tejun