Messages in this thread |  | | Date | Wed, 22 Oct 2014 21:45:52 +0200 | From | Dominik Dingel <> | Subject | Re: [PATCH 2/4] mm: introduce mm_forbids_zeropage function |
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On Wed, 22 Oct 2014 12:22:23 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed, 22 Oct 2014 13:09:28 +0200 Dominik Dingel <dingel@linux.vnet.ibm.com> wrote: > > > Add a new function stub to allow architectures to disable for > > an mm_structthe backing of non-present, anonymous pages with > > read-only empty zero pages. > > > > ... > > > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -56,6 +56,10 @@ extern int sysctl_legacy_va_layout; > > #define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0)) > > #endif > > > > +#ifndef mm_forbids_zeropage > > +#define mm_forbids_zeropage(X) (0) > > +#endif > > Can we document this please? What it does, why it does it. We should > also specify precisely which arch header file is responsible for > defining mm_forbids_zeropage. >
I will add a comment like:
/* * To prevent common memory management code establishing * a zero page mapping on a read fault. * This function should be implemented within <asm/pgtable.h>. * s390 does this to prevent multiplexing of hardware bits * related to the physical page in case of virtualization. */
Okay?
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