On Thu, Oct 18, 2012 at 01:50:14PM -0700, Yinghai Lu wrote:
> After we add code use buffer in BRK to pre-map page table,
^- to
So .. which patch is that? Can you include the title of the
patch here?
> it should be safe to remove early_memmap for page table accessing.
> Instead we get panic with that.
>
> It turns out we clear the initial page table wrongly for next range that is
^- that
> separated by holes.
> And it only happens when we are trying to map range one by one range
> separately.
^-s
>
> We need to check if the range is ram before clearing page table.
Ok, so that sounds like a bug-fix... but
>
> Signed-off-by: Yinghai Lu <ying...@kernel.org>
> ---
> arch/x86/mm/init_64.c | 37 ++++++++++++++++---------------------
> 1 files changed, 16 insertions(+), 21 deletions(-)
>
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index f40f383..61b3c44 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -363,20 +363,19 @@ static unsigned long __meminit
> phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
> pgprot_t prot)
> {
> - unsigned pages = 0;
> + unsigned long pages = 0, next;
> unsigned long last_map_addr = end;
> int i;
>
> pte_t *pte = pte_page + pte_index(addr);
>
> - for(i = pte_index(addr); i < PTRS_PER_PTE; i++, addr += PAGE_SIZE,
> pte++) {
> -
> + for (i = pte_index(addr); i < PTRS_PER_PTE; i++, addr = next, pte++) {
> + next = (addr & PAGE_MASK) + PAGE_SIZE;
> if (addr >= end) {
> - if (!after_bootmem) {
> - for(; i < PTRS_PER_PTE; i++, pte++)
> - set_pte(pte, __pte(0));
> - }
> - break;
> + if (!after_bootmem &&
> + !e820_any_mapped(addr & PAGE_MASK, next, 0))
> + set_pte(pte, __pte(0));
> + continue;
.. Interestingly, you also removed the extra loop. How come? Why not
retain the little loop? (which could call e820_any_mapped?) Is that
an improvement and cleanup? If so, I would think you should at least
explain in the git commit:
"And while we are at it, also axe the extra loop and instead depend on
the top loop which we can safely piggyback on."
> }
>
> /*
> @@ -418,16 +417,14 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address,
> unsigned long end,
> pte_t *pte;
> pgprot_t new_prot = prot;
>
> + next = (address & PMD_MASK) + PMD_SIZE;
> if (address >= end) {
> - if (!after_bootmem) {
> - for (; i < PTRS_PER_PMD; i++, pmd++)
> - set_pmd(pmd, __pmd(0));
> - }
> - break;
> + if (!after_bootmem &&
> + !e820_any_mapped(address & PMD_MASK, next, 0))
> + set_pmd(pmd, __pmd(0));
> + continue;
> }
>
> - next = (address & PMD_MASK) + PMD_SIZE;
> -
> if (pmd_val(*pmd)) {
> if (!pmd_large(*pmd)) {
> spin_lock(&init_mm.page_table_lock);
> @@ -494,13 +491,11 @@ phys_pud_init(pud_t *pud_page, unsigned long addr,
> unsigned long end,
> pmd_t *pmd;
> pgprot_t prot = PAGE_KERNEL;
>
> - if (addr >= end)
> - break;
> -
> next = (addr & PUD_MASK) + PUD_SIZE;
> -
> - if (!after_bootmem && !e820_any_mapped(addr, next, 0)) {
> - set_pud(pud, __pud(0));
> + if (addr >= end) {
> + if (!after_bootmem &&
> + !e820_any_mapped(addr & PUD_MASK, next, 0))
> + set_pud(pud, __pud(0));
> continue;
> }
>
> --
> 1.7.7
>
> --
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