Re: [PATCH v2 16/22] ARM: mm: cleanup checks for membank overlapwith vmalloc area

From: Nicolas Pitre
Date: Mon Sep 10 2012 - 14:07:30 EST


On Mon, 10 Sep 2012, Cyril Chemparathy wrote:

> On 8/12/2012 12:36 AM, Nicolas Pitre wrote:
> > On Fri, 10 Aug 2012, Cyril Chemparathy wrote:
> >
> > > On Keystone platforms, physical memory is entirely outside the 32-bit
> > > addressible range. Therefore, the (bank->start > ULONG_MAX) check below
> > > marks
> > > the entire system memory as highmem, and this causes unpleasentness all
> > > over.
> > >
> > > This patch eliminates the extra bank start check (against ULONG_MAX) by
> > > checking bank->start against the physical address corresponding to
> > > vmalloc_min
> > > instead.
> > >
> > > In the process, this patch also cleans up parts of the highmem sanity
> > > check
> > > code by removing what has now become a redundant check for banks that
> > > entirely
> > > overlap with the vmalloc range.
> >
> > Are you sure of this? The code that you removed not only checks for
> > banks that fall into the vmalloc area, but it also skipp them. This is
> > now lost.
> >
>
> I almost missed out on this email...
>
> The check is not quite lost, we still have the following in the
> !CONFIG_HIGHMEM block:
>
> if (highmem) {
> printk(...);
> continue;
> }
>
> The change is that highmem is now set outside the #ifdef when (bank->start >=
> vmalloc_limit), and therefore the check is truly redundant.

OK.

Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>



>
> > > Signed-off-by: Cyril Chemparathy <cyril@xxxxxx>
> > > Signed-off-by: Vitaly Andrianov <vitalya@xxxxxx>
> > > ---
> > > arch/arm/mm/mmu.c | 19 +------------------
> > > 1 file changed, 1 insertion(+), 18 deletions(-)
> > >
> > > diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> > > index f764c03..3d685c6 100644
> > > --- a/arch/arm/mm/mmu.c
> > > +++ b/arch/arm/mm/mmu.c
> > > @@ -901,15 +901,12 @@ void __init sanity_check_meminfo(void)
> > > struct membank *bank = &meminfo.bank[j];
> > > *bank = meminfo.bank[i];
> > >
> > > - if (bank->start > ULONG_MAX)
> > > - highmem = 1;
> > > -
> > > -#ifdef CONFIG_HIGHMEM
> > > if (bank->start >= vmalloc_limit)
> > > highmem = 1;
> > >
> > > bank->highmem = highmem;
> > >
> > > +#ifdef CONFIG_HIGHMEM
> > > /*
> > > * Split those memory banks which are partially overlapping
> > > * the vmalloc area greatly simplifying things later.
> > > @@ -932,8 +929,6 @@ void __init sanity_check_meminfo(void)
> > > bank->size = vmalloc_limit - bank->start;
> > > }
> > > #else
> > > - bank->highmem = highmem;
> > > -
> > > /*
> > > * Highmem banks not allowed with !CONFIG_HIGHMEM.
> > > */
> > > @@ -946,18 +941,6 @@ void __init sanity_check_meminfo(void)
> > > }
> > >
> > > /*
> > > - * Check whether this memory bank would entirely overlap
> > > - * the vmalloc area.
> > > - */
> > > - if (bank->start >= vmalloc_limit) {
> > > - printk(KERN_NOTICE "Ignoring RAM at %.8llx-%.8llx "
> > > - "(vmalloc region overlap).\n",
> > > - (unsigned long long)bank->start,
> > > - (unsigned long long)bank->start + bank->size -
> > > 1);
> > > - continue;
> > > - }
> > > -
> > > - /*
> > > * Check whether this memory bank would partially overlap
> > > * the vmalloc area.
> > > */
> > > --
> > > 1.7.9.5
> > >
>
> --
> Thanks
> - Cyril
>
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