Messages in this thread | | | Date | Thu, 23 Jun 2011 13:56:38 +0100 | From | Stefano Stabellini <> | Subject | Re: [PATCH] x86_64: do not assume head_64.S used 4KB pages when !use_pse |
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On Thu, 23 Jun 2011, Penttilä Mika wrote: > > From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > > head_64.S, which sets up the initial page table on x86_64, is not aware > > of PSE being enabled or disabled and it always allocates the initial > > mapping using 2MB pages. > > > Therefore on x86_64 find_early_table_space shouldn't update the amount > > of pages needed for pte pages depending on the size of the initial > > mapping, because we know for sure that no pte pages have been allocated > > yet. > > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > Reported-by: Ingo Molnar <mingo@elte.hu> > > --- > > arch/x86/mm/init.c | 7 +++++++ > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > > index 36bacfe..1e3098b 100644 > > --- a/arch/x86/mm/init.c > > +++ b/arch/x86/mm/init.c > > @@ -42,12 +42,19 @@ static void __init find_early_table_space(unsigned long start, > > (PMD_SIZE * PTRS_PER_PMD)); > > pmd_mapped *= (PMD_SIZE * PTRS_PER_PMD); > > > > + /* > > + * On x86_64 do not limit the size we need to cover with 4KB pages > > + * depending on the initial allocation because head_64.S always uses > > + * 2MB pages. > > + */ > > +#ifdef CONFIG_X86_32 > > if (start < PFN_PHYS(max_pfn_mapped)) { > > if (PFN_PHYS(max_pfn_mapped) < end) > > size -= PFN_PHYS(max_pfn_mapped) - start; > > else > > size = 0; > > } > > +#endif > > And arch/x86/mm/init.c also has: > > #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK) > /* > * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages. > * This will simplify cpa(), which otherwise needs to support splitting > * large pages into small in interrupt context, etc. > */ > use_pse = use_gbpages = 0; > #else > use_pse = cpu_has_pse; > use_gbpages = direct_gbpages; > #endif > > > So big pages are also not used for DEBUG_PAGEALLOC and KMEMCHECK configs even if head_32.S did.
Right, but that is not a problem because head_32.S always uses 4KB pages. | |