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

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Message-ID: <20171127205421.GR983427@devbig577.frc2.facebook.com>
Date:   Mon, 27 Nov 2017 12:54:21 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Nicolas Pitre <nicolas.pitre@...aro.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        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)

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.

Thanks!

-- 
tejun