From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E852C433EF for ; Mon, 2 May 2022 05:32:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B6B8A6B0073; Mon, 2 May 2022 01:32:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B1B696B0074; Mon, 2 May 2022 01:32:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9E2F06B0075; Mon, 2 May 2022 01:32:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 9058C6B0073 for ; Mon, 2 May 2022 01:32:05 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 65E202B11D for ; Mon, 2 May 2022 05:32:05 +0000 (UTC) X-FDA: 79419681810.08.293A504 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf08.hostedemail.com (Postfix) with ESMTP id 7242D16006D for ; Mon, 2 May 2022 05:31:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ZMITGLh21gLnSqeHOMeNStOSsEkAvssgxNSH4ttTFCE=; b=f4z0wrZH8kKCnmp6s4m91ky+JQ Y7y3VxOmRTr1Zzg9njaHsIWjkxIRhb5xSGulmg73pK10S8i6TJdL/qUzyF7laqnvUWAZdFttP5iG8 hjWYEk6bk0XAxVSP0lfR0kHUEmBSjvSge0Q45VB7O6zCj6tkGBujqZMczCJm4LJHmtvFKmCOiORr6 dmg8h9YYNpKWgNFqJq0sPoozuvzQ+IQeEA/WkYfirSv0NdAgbJVrCrJGxA/2Q9CKxYgYhyxTwYSzn F+o3WPVHZmMzMfLF4rFcKewRRgdIb6/Xy4t4NpmO1gUnEEaTxlYHuxmDAmtJnsFvQllf5aTQgddoD rzqys59w==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nlOf6-00EYar-Bg; Mon, 02 May 2022 05:31:56 +0000 Date: Mon, 2 May 2022 06:31:56 +0100 From: Matthew Wilcox To: NeilBrown Cc: Miaohe Lin , Andrew Morton , Geert Uytterhoeven , Christoph Hellwig , linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] MM: handle THP in swap_*page_fs() - count_vm_events() Message-ID: References: <165146746627.24404.2324091720943354711@noble.neil.brown.name> <165146932944.24404.17790836056748683378@noble.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <165146932944.24404.17790836056748683378@noble.neil.brown.name> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7242D16006D Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=f4z0wrZH; spf=none (imf08.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspam-User: X-Stat-Signature: 3sjp41bhmhopottgoits8zt9q964rk9k X-HE-Tag: 1651469516-679421 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 02, 2022 at 03:28:49PM +1000, NeilBrown wrote: > On Mon, 02 May 2022, Matthew Wilcox wrote: > > On Mon, May 02, 2022 at 02:57:46PM +1000, NeilBrown wrote: > > > @@ -390,9 +392,9 @@ static void sio_read_complete(struct kiocb *iocb, long ret) > > > struct page *page = sio->bvec[p].bv_page; > > > > > > SetPageUptodate(page); > > > + count_swpout_vm_event(page); > > > unlock_page(page); > > > } > > > - count_vm_events(PSWPIN, sio->pages); > > > > Surely that should be count_swpIN_vm_event? > > > I'm not having a good day.... > > Certainly shouldn't be swpout. There isn't a count_swpin_vm_event(). > > swap_readpage() only counts once for each page no matter how big it is. > While swap_writepage() counts one for each PAGE_SIZE written. > > And we have THP_SWPOUT but not THP_SWPIN _If_ I understand the swap-in patch correctly (at least as invoked by shmem), it won't attempt to swap in an entire THP. Even if it swapped out an order-9 page, it will bring in order-0 pages from swap, and then rely on khugepaged to reassemble them. Someone who actually understands the swap code should check that my explanation here is correct.