On Fri, Jan 29, 2010 at 01:56:32PM -0500, David Daney wrote: > Guenter Roeck wrote: > > On Fri, Jan 29, 2010 at 01:06:20PM -0500, Ralf Baechle wrote: > >> On Fri, Jan 29, 2010 at 09:11:46AM -0800, David Daney wrote: > >> > >>>> So first question would be: Has anyone successfully loaded a 64 > >>>> bit mips kernel with 2.6.32 and a page size of 16k or 64k ? This > >>>> would at least help me reducing the problem to sb1. > >>> Yes, I routinely run with both 64K and 16K page sizes on 2.6.32 and > >>> 2.6.33-rc*. I have not seen any crashes that can not be easily > >>> explained. > >> I can reproduce it with today's 14b7baff3eb4b1b46a592630e6f85ded9264798a. > >> 4K page size works ok, 16K without IPv6 works ok and 16K with IPv6 crashes. > >> Note, I was testing with a non-16K capable userland so ok means userland is > >> reached. > >> > >> Either way, that's good enought to look into things. > >> > > 16k page size works for me with the patch below. Not that I have any idea why; > > this was just a blind test. > > > > It seems to me that the notes in arch/mips/include/asm/pgtable-64.h regarding > > available virtual memory per page size may contradict with the definition > > of VMALLOC_END. VMALLOC_END-VMALLOC_START increases as the page size increases, > > but the comments indicate that a system with 16k pages should have _less_ > > virtual memory available than a system with 4k pages because it only uses > > a 2 level page table. > > > > Guenter > > > > --------------- > > > > git diff arch/mips/include/asm/pgtable-64.h > > diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h > > index 9cd5089..bd61030 100644 > > --- a/arch/mips/include/asm/pgtable-64.h > > +++ b/arch/mips/include/asm/pgtable-64.h > > @@ -110,7 +110,7 @@ > > #define VMALLOC_START MAP_BASE > > #define VMALLOC_END \ > > (VMALLOC_START + \ > > - PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE - (1UL << 32)) > > + (PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE / 16) - (1UL << 32)) > > #if defined(CONFIG_MODULES) && defined(KBUILD_64BIT_SYM32) && \ > > VMALLOC_START != CKSSEG > > /* Load modules into 32bit-compatible segment. */ > > Although it may fix it, I think something along the lines of this: > > In asm/mach-generic/spaces.h: > #define MAX_VIRTUAL_SIZE (1 << some number) > > In asm/mach-sibyte/paces.h: > #define MAX_VIRTUAL_SIZE (1 << some other umber) > > In arch/mips/include/asm/pgtable-64.h > > #define VIRTUAL_SIZE (PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * > PAGE_SIZE) > > #define VMALLOC_END (VMALLOC_START + min(MAX_VIRTUAL_SIZE, VIRTUAL_SIZE) > - (1UL << 32)) Something like that. My patch wasn't supposed to be a proposal for a fix, just a guide to help finding the underlying problem. It may require some factor related to the page size. Someone who knows mips and its memory management scheme should have a look, otherwise it would just be a trial-end-error fix. Guenter
