From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx189.postini.com [74.125.245.189]) by kanga.kvack.org (Postfix) with SMTP id F154C6B002B for ; Mon, 8 Oct 2012 01:17:59 -0400 (EDT) Message-ID: <50726354.60803@cn.fujitsu.com> Date: Mon, 08 Oct 2012 13:23:32 +0800 From: Wen Congyang MIME-Version: 1.0 Subject: Re: [PATCH 8/10] memory-hotplug : remove page table of x86_64 architecture References: <506E43E0.70507@jp.fujitsu.com> <506E4799.30407@jp.fujitsu.com> In-Reply-To: Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: Yasuaki Ishimatsu , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com At 10/08/2012 12:37 PM, Andi Kleen Wrote: > Yasuaki Ishimatsu 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(); > > 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: email@kvack.org