Messages in this thread | | | Date | Thu, 11 Oct 2012 08:35:50 +0800 | From | Ni zhan Chen <> | Subject | Re: [PATCH 8/10] memory-hotplug : remove page table of x86_64 architecture |
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On 10/08/2012 01:23 PM, Wen Congyang wrote: > At 10/08/2012 12:37 PM, Andi Kleen Wrote: >> Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> writes: >>> + } >>> + >>> + /* >>> + * We use 2M page, but we need to remove part of them, >>> + * so split 2M page to 4K page. >>> + */ >>> + pte = alloc_low_page(&pte_phys); >> What happens when the allocation fails? >> >> alloc_low_page seems to be buggy there too, it would __pa a NULL >> pointer. > Yes, it will cause kernek panicked in __pa() if CONFI_DEBUG_VIRTUAL is set. > Otherwise, it will return a NULL pointer. I will update this patch to deal > with NULL pointer. > >>> + if (pud_large(*pud)) { >>> + if ((addr & ~PUD_MASK) == 0 && next <= end) { >>> + set_pud(pud, __pud(0)); >>> + pages++; >>> + continue; >>> + } >>> + >>> + /* >>> + * We use 1G page, but we need to remove part of them, >>> + * so split 1G page to 2M page. >>> + */ >>> + pmd = alloc_low_page(&pmd_phys); >> Same here >> >>> + __split_large_page((pte_t *)pud, addr, (pte_t *)pmd); >>> + >>> + spin_lock(&init_mm.page_table_lock); >>> + pud_populate(&init_mm, pud, __va(pmd_phys)); >>> + spin_unlock(&init_mm.page_table_lock); >>> + } >>> + >>> + pmd = map_low_page(pmd_offset(pud, 0)); >>> + phys_pmd_remove(pmd, addr, end); >>> + unmap_low_page(pmd); >>> + __flush_tlb_all(); >>> + } >>> + __flush_tlb_all();
Hi Congyang,
I see you call __flush_tlb_all() every pud entry(all pmd, pte related to it changed) modified, then how to determine the flush frequency? why not every pmd entry?
Regards, Chen
>> This doesn't flush the other CPUs doesn't it? > How to flush the other CPU's tlb? use on_each_cpu() to run __flush_tlb_all() > on each online cpu? > > Thanks > Wen Congyang > >> -Andi >> > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> >
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