On 10/08/2012 01:23 PM, Wen Congyang wrote:
At 10/08/2012 12:37 PM, Andi Kleen Wrote:
Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> 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
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