From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx155.postini.com [74.125.245.155]) by kanga.kvack.org (Postfix) with SMTP id 7CC346B0005 for ; Mon, 25 Feb 2013 11:58:14 -0500 (EST) Date: Mon, 25 Feb 2013 11:57:56 -0500 From: Naoya Horiguchi Message-ID: <1361811476-la4ql3y2-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: References: <1361475708-25991-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1361475708-25991-9-git-send-email-n-horiguchi@ah.jp.nec.com> Subject: Re: [PATCH 8/9] memory-hotplug: enable memory hotplug to handle hugepage Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , linux-kernel@vger.kernel.org, Michal Hocko Hi Hillf, On Sat, Feb 23, 2013 at 03:05:30PM +0800, Hillf Danton wrote: > Hello Naoya > > [add Michal in cc list] > > On Fri, Feb 22, 2013 at 3:41 AM, Naoya Horiguchi > wrote: > > > > +/* Returns true for head pages of in-use hugepages, otherwise returns false. */ > > +int is_hugepage_movable(struct page *hpage) > s/int/bool/ can we? Yes, we can. I'll do this. > > +{ > > + struct page *page; > > + struct page *tmp; > > + struct hstate *h = page_hstate(hpage); > Make sense to compute hstate for a tail page? No need to do this here. It's better to put it after PageTail check. > > + int ret = 0; > > + > > + VM_BUG_ON(!PageHuge(hpage)); > > + if (PageTail(hpage)) > > + return 0; > VM_BUG_ON(!PageHuge(hpage) || PageTail(hpage)), can we? I think that firing BUG_ON() for tail pages is overkill. Pfn range over which scan_movable_pages() runs could start at the pfn inside the hugepage when we try to hot-remove the memory block used by 1GB hugepage. In that case, is_hugepage_movable() can be called for tail pages as a normal behavior. But anyway, I'll add the comment for this corner case. > > + spin_lock(&hugetlb_lock); > > + list_for_each_entry_safe(page, tmp, &h->hugepage_activelist, lru) > s/_safe// can we? OK. > > + if (page == hpage) > > + ret = 1; > Can we bail out with ret set to be true? Yes, inserting break is good for performance. > > + spin_unlock(&hugetlb_lock); > > + return ret; > > +} Thank you! Naoya -- 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