Re: [Patch v4 09/12] memory-hotplug: remove page table of x86_64 architecture
From: Tang Chen <hidden>
Date: 2012-12-07 06:44:48
Also in:
linux-acpi, linux-mm, linux-s390, linux-sh, lkml, sparclinux
On 11/27/2012 06:00 PM, Wen Congyang wrote:
For hot removing memory, we sholud remove page table about the memory. So the patch searches a page table about the removed memory, and clear page table.
(snip)
+void __meminit
+kernel_physical_mapping_remove(unsigned long start, unsigned long end)
+{
+ unsigned long next;
+ bool pgd_changed = false;
+
+ start = (unsigned long)__va(start);
+ end = (unsigned long)__va(end);Hi Wu, Here, you expect start and end are physical addresses. But in phys_xxx_remove() function, I think using virtual addresses is just fine. Functions like pmd_addr_end() and pud_index() only calculate an offset. So, would you please tell me if we have to use physical addresses here ? Thanks. :)
quoted hunk ↗ jump to hunk
+ + for (; start< end; start = next) { + pgd_t *pgd = pgd_offset_k(start); + pud_t *pud; + + next = pgd_addr_end(start, end); + + if (!pgd_present(*pgd)) + continue; + + pud = map_low_page((pud_t *)pgd_page_vaddr(*pgd)); + phys_pud_remove(pud, __pa(start), __pa(next)); + if (free_pud_table(pud, pgd)) + pgd_changed = true; + unmap_low_page(pud); + } + + if (pgd_changed) + sync_global_pgds(start, end - 1); + + flush_tlb_all(); +} + #ifdef CONFIG_MEMORY_HOTREMOVE int __ref arch_remove_memory(u64 start, u64 size) {@@ -692,6 +921,8 @@ int __ref arch_remove_memory(u64 start, u64 size) ret = __remove_pages(zone, start_pfn, nr_pages); WARN_ON_ONCE(ret); + kernel_physical_mapping_remove(start, start + size); + return ret; } #endif