On Wed, 2007-08-01 at 16:02 +1000, Michael Neuling wrote:
> We sometimes change the vmalloc segment in slb_flush_and_rebolt but we
> never updated with slb shadow buffer. This fixes it. Thanks to paulus
> for finding this.
>
> Also added some write barriers to ensure the shadow buffer is always
> valid.
The shadow is global or per-cpu ?
Because in the later case, I think you need more than that.
> Index: linux-2.6-ozlabs/arch/powerpc/mm/hash_utils_64.c
> ===================================================================
> --- linux-2.6-ozlabs.orig/arch/powerpc/mm/hash_utils_64.c
> +++ linux-2.6-ozlabs/arch/powerpc/mm/hash_utils_64.c
> @@ -629,6 +629,9 @@ int hash_page(unsigned long ea, unsigned
> cpumask_t tmp;
> int rc, user_region = 0, local = 0;
> int psize;
> +#ifdef CONFIG_PPC_64K_PAGES
> + unsigned long vflags;
> +#endif
>
> DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
> ea, access, trap);
> @@ -759,6 +762,9 @@ int hash_page(unsigned long ea, unsigned
> mmu_psize_defs[mmu_vmalloc_psize].sllp) {
> get_paca()->vmalloc_sllp =
> mmu_psize_defs[mmu_vmalloc_psize].sllp;
> + vflags = SLB_VSID_KERNEL |
> + mmu_psize_defs[mmu_vmalloc_psize].sllp;
> + slb_shadow_update(VMALLOC_START, vflags, 1);
> slb_flush_and_rebolt();
> }
Later on:
} else if (get_paca()->vmalloc_sllp !=
mmu_psize_defs[mmu_vmalloc_psize].sllp) {
get_paca()->vmalloc_sllp =
mmu_psize_defs[mmu_vmalloc_psize].sllp;
slb_flush_and_rebolt();
}
If your shadow is per-cpu, you need to fix that up too.
I'm tempted to think you should just expose an slb_vmalloc_update()
from slb.c that does the shadow update and calls flush_and_rebolt.
That would also get rid of your ifdef on vflags definition (which
wasn't necessary in the first place if you had put it inside the
if statement anyway).
Ben.
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