From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx139.postini.com [74.125.245.139]) by kanga.kvack.org (Postfix) with SMTP id 288A86B0099 for ; Thu, 15 Nov 2012 03:14:20 -0500 (EST) Received: by mail-pa0-f41.google.com with SMTP id fa10so987713pad.14 for ; Thu, 15 Nov 2012 00:14:19 -0800 (PST) Date: Thu, 15 Nov 2012 00:14:17 -0800 (PST) From: David Rientjes Subject: Re: [PATCH v5 03/11] thp: copy_huge_pmd(): copy huge zero page In-Reply-To: <20121115080133.GA9676@otc-wbsnb-06> Message-ID: References: <1352300463-12627-1-git-send-email-kirill.shutemov@linux.intel.com> <1352300463-12627-4-git-send-email-kirill.shutemov@linux.intel.com> <20121115080133.GA9676@otc-wbsnb-06> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Andrew Morton , Andrea Arcangeli , linux-mm@kvack.org, Andi Kleen , "H. Peter Anvin" , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" On Thu, 15 Nov 2012, Kirill A. Shutemov wrote: > > > @@ -778,6 +790,11 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, > > > pte_free(dst_mm, pgtable); > > > goto out_unlock; > > > } > > > + if (is_huge_zero_pmd(pmd)) { > > > + set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd); > > > + ret = 0; > > > + goto out_unlock; > > > + } > > > > You said in the introduction message in this series that you still allow > > splitting of the pmd, so why no check for pmd_trans_splitting() before > > this? > > pmd_trans_splitting() returns true only for pmd which points to a page > under spliiting. It never happens with huge zero page. > We only split a pmd to a page table without touching the page. > mm->page_table_lock is enough to protect against that. > Comment in the code? -- 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