Re: [PATCH] ARM:mm: define arch-specific IOREMAP_MAX_ORDER only in !SMP && !LPAE case

[Sergey Dyasly]

On 09.09.2015 6:10, Nicolas Pitre wrote:
> On Tue, 8 Sep 2015, Sergey Dyasly wrote:
>
> > On 08.09.2015 5:45, Zhang Zhen wrote:
> > > The arch-specific IOREMAP_MAX_ORDER is introduced in
> > > commit: ff0daca([ARM] Add section support to ioremap) and
> > > commit: a069c89 ([ARM] 3705/1: add supersection support to ioremap()).
> > > But supersections and sections mappings are only used in !SMP && !LPAE case.
> > > Otherwise, mapping is created using the usual 4K pages.
> > >
> > > In most cases without !SMP && !LPAE, the big alignment cause high
> > > fragmentation
> > > issue in vmalloc area.
> > > Here we use arch-specific IOREMAP_MAX_ORDER only in !SMP && !LPAE case,
> > > otherwise use generic IOREMAP_MAX_ORDER in include/linux/vmalloc.h.
> > >
> > > Signed-off-by: Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx>
> > > ---
> > >    arch/arm/include/asm/memory.h | 2 ++
> > >    1 file changed, 2 insertions(+)
> > >
> > > diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> > > index b7f6fb4..3209012 100644
> > > --- a/arch/arm/include/asm/memory.h
> > > +++ b/arch/arm/include/asm/memory.h
> > > @@ -76,10 +76,12 @@
> > >     */
> > >    #define XIP_VIRT_ADDR(physaddr)  (MODULES_VADDR + ((physaddr) &
> > > 0x000fffff))
> > >
> > > +#if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
> > >    /*
> > >     * Allow 16MB-aligned ioremap pages
> > >     */
> > >    #define IOREMAP_MAX_ORDER	24
> > > +#endif
> > >
> > >    #else /* CONFIG_MMU */
> > Hmm... This looks exactly like my old patch -
> > http://thread.gmane.org/gmane.linux.kernel.mm/127620
> > (Thanks to Vladimir for pointing that out!)
> >
> > Hasn't there been any progress about this issue?
> IMHO the patch makes sense.
>
> Did you send it to RMK's patch system?
Ok, submitted it to the patch system. Thanks!

> Nicolas

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