Subject: Re: powerpc/mm: Only define MAX_PHYSMEM_BITS in SPARSEMEM configurations

From: Michael Ellerman <[email-masked]>
Date: Fri, 22 Mar 2019 23:21:40 +1100 (AEDT)

On Sun, 2019-03-17 at 01:17:56 UTC, Ben Hutchings wrote:
> MAX_PHYSMEM_BITS only needs to be defined if CONFIG_SPARSEMEM is
> enabled, and that was the case before commit 4ffe713b7587
> ("powerpc/mm: Increase the max addressable memory to 2PB").
> 
> On 32-bit systems, where CONFIG_SPARSEMEM is not enabled, we now
> define it as 46.  That is larger than the real number of physical
> address bits, and breaks calculations in zsmalloc:
> 
>     mm/zsmalloc.c:130:49: warning: right shift count is negative [-Wshift-count-negative]
>       MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
>                                                      ^~
>     ...
>     mm/zsmalloc.c:253:21: error: variably modified 'size_class' at file scope
>       struct size_class *size_class[ZS_SIZE_CLASSES];
>                          ^~~~~~~~~~
> 
> Fixes: 4ffe713b7587 ("powerpc/mm: Increase the max addressable memory to 2PB")
> Cc: [email-masked]
> Signed-off-by: Ben Hutchings <[email-masked]>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/8bc086899816214fbc6047c9c7e15fca

cheers