From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 8DDAF6B0038 for ; Mon, 13 Feb 2017 09:32:50 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id u63so248866wmu.0 for ; Mon, 13 Feb 2017 06:32:50 -0800 (PST) Received: from mail-wm0-x243.google.com (mail-wm0-x243.google.com. [2a00:1450:400c:c09::243]) by mx.google.com with ESMTPS id o92si14081766wrb.25.2017.02.13.06.32.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 Feb 2017 06:32:49 -0800 (PST) Received: by mail-wm0-x243.google.com with SMTP id c85so19855239wmi.1 for ; Mon, 13 Feb 2017 06:32:49 -0800 (PST) Date: Mon, 13 Feb 2017 17:32:47 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCHv6 05/37] thp: try to free page's buffers before attempt split Message-ID: <20170213143247.GC20394@node.shutemov.name> References: <20170126115819.58875-1-kirill.shutemov@linux.intel.com> <20170126115819.58875-6-kirill.shutemov@linux.intel.com> <20170209201416.GS2267@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170209201416.GS2267@bombadil.infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox Cc: "Kirill A. Shutemov" , Theodore Ts'o , Andreas Dilger , Jan Kara , Andrew Morton , Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org On Thu, Feb 09, 2017 at 12:14:16PM -0800, Matthew Wilcox wrote: > On Thu, Jan 26, 2017 at 02:57:47PM +0300, Kirill A. Shutemov wrote: > > @@ -2146,6 +2146,23 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > > goto out; > > } > > > > + /* Try to free buffers before attempt split */ > > + if (!PageSwapBacked(head) && PagePrivate(page)) { > > + /* > > + * We cannot trigger writeback from here due possible > > + * recursion if triggered from vmscan, only wait. > > + * > > + * Caller can trigger writeback it on its own, if safe. > > + */ > > It took me a few reads to get this. May I suggest: > > /* > * Cannot split a page with buffers. If the caller has > * already started writeback, we can wait for it to finish, > * but we cannot start writeback if we were called from vmscan > */ Yeah, that's better. > > + if (!PageSwapBacked(head) && PagePrivate(page)) { > > Also, it looks weird to test PageSwapBacked of *head* and PagePrivate > of *page*. I think it's correct, but it still looks weird. I'll change this. > Reviewed-by: Matthew Wilcox Thanks! -- Kirill A. Shutemov -- 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