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 448ACC433F5 for ; Mon, 2 May 2022 17:49:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B394C6B0071; Mon, 2 May 2022 13:49:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AE7F56B0073; Mon, 2 May 2022 13:49:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 98A2E6B0074; Mon, 2 May 2022 13:49:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 8A01A6B0071 for ; Mon, 2 May 2022 13:49:03 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 56B656171D for ; Mon, 2 May 2022 17:49:03 +0000 (UTC) X-FDA: 79421538966.20.E0212E8 Received: from mail-pj1-f42.google.com (mail-pj1-f42.google.com [209.85.216.42]) by imf08.hostedemail.com (Postfix) with ESMTP id 0E79916005F for ; Mon, 2 May 2022 17:48:53 +0000 (UTC) Received: by mail-pj1-f42.google.com with SMTP id w5-20020a17090aaf8500b001d74c754128so24312pjq.0 for ; Mon, 02 May 2022 10:49:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=COitYDD2QK7Io8HotGUG1E8FA+/THRtBu4YhBbnt/9Y=; b=HOyChXNPd0gP8UKUBeE83hBU+0I2BPcZUG97FRQMY6OdeL1mY1npyxO6BZgT3VAeAp 0elyzuO/naP/5I+8qrVeGHEnOFq/CcW0LCmKn9XPrUKUZasvV/MEP6aT/NyAr7ys++0B J44ALS2noyL9fwIcrl6+QM1i/Rj+mPZYo347HeVMJ1U2xzedNrK4kyg1F52zm26VtIkU t5Yb3R3eWyrMd/KGCDJWKL42ROc0YefM3H6fx3URH4r86wVEX+mDLM+OcCRYqD7oYATm PUtxnJrhRMeiYuhPsn+KfyOqm7MHqqbAWntdfLi4mjt2D03YdLlKT3X1E4MZzYsMM6wU OtSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=COitYDD2QK7Io8HotGUG1E8FA+/THRtBu4YhBbnt/9Y=; b=bavIoZHaBQm2RN1oU56Fsfsr4a/mN6AcerBKne8u6FDFsmB+rPNRr70SG3jbaWwQeL tgQ+bpMHgEkdlcjkrrjDOhpro8YQZgtPDxBcJ90r9WobRqcurEWpxVz+OuUwKzfvxRLO h3v4uoB7AnZ5uaJa+6ySWbCx3c8CEFLikngTL0dzs1cak0tkfUkAolDkTMt+pNondyJ7 7lAi9ZA8xM7uP5uMaYPWrg5xzm4uf1QBmHdWfEbx21Ye/WSZ+aEFsieE979lTn8pfmfk wkqrm6S8rmH1a3bzn4CKhXPG4f9JV2O+JxobRv9/tT5J9ShOHZGkmBJLlB/Z8fiJ++wk 9Cgg== X-Gm-Message-State: AOAM533kf75A3RD0LbNTh7tvW5mSrjmfuhVOMCo8WwZ2d3ngYH8yDRIV QUCGpVfR7g5ZdSLVh4d979XPMQpTilsOHRc3Eib5znum X-Google-Smtp-Source: ABdhPJw033z/wJCqMFoN48CqODTw8SowfGoCVw6iDHO+NnvXKCmKg2FFVSOMM6+brasxr0pC2UIGiFYYpF4KzZUBQ1c= X-Received: by 2002:a17:903:32d2:b0:15d:ea5:3e0f with SMTP id i18-20020a17090332d200b0015d0ea53e0fmr13007774plr.117.1651513741762; Mon, 02 May 2022 10:49:01 -0700 (PDT) MIME-Version: 1.0 References: <165119280115.15698.2629172320052218921.stgit@noble.brown> <165119301488.15698.9457662928942765453.stgit@noble.brown> <165146539609.24404.4051313590023463843@noble.neil.brown.name> In-Reply-To: <165146539609.24404.4051313590023463843@noble.neil.brown.name> From: Yang Shi Date: Mon, 2 May 2022 10:48:49 -0700 Message-ID: Subject: Re: [PATCH 1/2] MM: handle THP in swap_*page_fs() To: NeilBrown , Huang Ying Cc: Andrew Morton , Geert Uytterhoeven , Christoph Hellwig , Miaohe Lin , linux-nfs@vger.kernel.org, Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=HOyChXNP; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf08.hostedemail.com: domain of shy828301@gmail.com designates 209.85.216.42 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 0E79916005F X-Rspam-User: X-Stat-Signature: zwhp3zi8c8mje5d94gtggz1dk3y116h9 X-HE-Tag: 1651513733-81265 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 Sun, May 1, 2022 at 9:23 PM NeilBrown wrote: > > On Sat, 30 Apr 2022, Yang Shi wrote: > > On Thu, Apr 28, 2022 at 5:44 PM NeilBrown wrote: > > > > > > Pages passed to swap_readpage()/swap_writepage() are not necessarily all > > > the same size - there may be transparent-huge-pages involves. > > > > > > The BIO paths of swap_*page() handle this correctly, but the SWP_FS_OPS > > > path does not. > > > > > > So we need to use thp_size() to find the size, not just assume > > > PAGE_SIZE, and we need to track the total length of the request, not > > > just assume it is "page * PAGE_SIZE". > > > > Swap-over-nfs doesn't support THP swap IIUC. So SWP_FS_OPS should not > > see THP at all. But I agree to remove the assumption about page size > > in this path. > > Can you help me understand this please. How would the swap code know > that swap-over-NFS doesn't support THP swap? There is no reason that > NFS wouldn't be able to handle 2MB writes. Even 1GB should work though > NFS would have to split into several smaller WRITE requests. AFAICT, THP swap is only supported on non-rotate block devices, for example, SSD, PMEM, etc. IIRC, the swap device has to support the cluster in order to swap THP. The cluster is only supported by non-rotate block devices. Looped Ying in, who is the author of THP swap. > > Thanks, > NeilBrown > > > > > > > > > > Reported-by: Miaohe Lin > > > Signed-off-by: NeilBrown > > > --- > > > mm/page_io.c | 23 +++++++++++++---------- > > > 1 file changed, 13 insertions(+), 10 deletions(-) > > > > > > diff --git a/mm/page_io.c b/mm/page_io.c > > > index c132511f521c..d636a3531cad 100644 > > > --- a/mm/page_io.c > > > +++ b/mm/page_io.c > > > @@ -239,6 +239,7 @@ struct swap_iocb { > > > struct kiocb iocb; > > > struct bio_vec bvec[SWAP_CLUSTER_MAX]; > > > int pages; > > > + int len; > > > }; > > > static mempool_t *sio_pool; > > > > > > @@ -261,7 +262,7 @@ static void sio_write_complete(struct kiocb *iocb, long ret) > > > struct page *page = sio->bvec[0].bv_page; > > > int p; > > > > > > - if (ret != PAGE_SIZE * sio->pages) { > > > + if (ret != sio->len) { > > > /* > > > * In the case of swap-over-nfs, this can be a > > > * temporary failure if the system has limited > > > @@ -301,7 +302,7 @@ static int swap_writepage_fs(struct page *page, struct writeback_control *wbc) > > > sio = *wbc->swap_plug; > > > if (sio) { > > > if (sio->iocb.ki_filp != swap_file || > > > - sio->iocb.ki_pos + sio->pages * PAGE_SIZE != pos) { > > > + sio->iocb.ki_pos + sio->len != pos) { > > > swap_write_unplug(sio); > > > sio = NULL; > > > } > > > @@ -312,10 +313,12 @@ static int swap_writepage_fs(struct page *page, struct writeback_control *wbc) > > > sio->iocb.ki_complete = sio_write_complete; > > > sio->iocb.ki_pos = pos; > > > sio->pages = 0; > > > + sio->len = 0; > > > } > > > sio->bvec[sio->pages].bv_page = page; > > > - sio->bvec[sio->pages].bv_len = PAGE_SIZE; > > > + sio->bvec[sio->pages].bv_len = thp_size(page); > > > sio->bvec[sio->pages].bv_offset = 0; > > > + sio->len += thp_size(page); > > > sio->pages += 1; > > > if (sio->pages == ARRAY_SIZE(sio->bvec) || !wbc->swap_plug) { > > > swap_write_unplug(sio); > > > @@ -371,8 +374,7 @@ void swap_write_unplug(struct swap_iocb *sio) > > > struct address_space *mapping = sio->iocb.ki_filp->f_mapping; > > > int ret; > > > > > > - iov_iter_bvec(&from, WRITE, sio->bvec, sio->pages, > > > - PAGE_SIZE * sio->pages); > > > + iov_iter_bvec(&from, WRITE, sio->bvec, sio->pages, sio->len); > > > ret = mapping->a_ops->swap_rw(&sio->iocb, &from); > > > if (ret != -EIOCBQUEUED) > > > sio_write_complete(&sio->iocb, ret); > > > @@ -383,7 +385,7 @@ static void sio_read_complete(struct kiocb *iocb, long ret) > > > struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb); > > > int p; > > > > > > - if (ret == PAGE_SIZE * sio->pages) { > > > + if (ret == sio->len) { > > > for (p = 0; p < sio->pages; p++) { > > > struct page *page = sio->bvec[p].bv_page; > > > > > > @@ -415,7 +417,7 @@ static void swap_readpage_fs(struct page *page, > > > sio = *plug; > > > if (sio) { > > > if (sio->iocb.ki_filp != sis->swap_file || > > > - sio->iocb.ki_pos + sio->pages * PAGE_SIZE != pos) { > > > + sio->iocb.ki_pos + sio->len != pos) { > > > swap_read_unplug(sio); > > > sio = NULL; > > > } > > > @@ -426,10 +428,12 @@ static void swap_readpage_fs(struct page *page, > > > sio->iocb.ki_pos = pos; > > > sio->iocb.ki_complete = sio_read_complete; > > > sio->pages = 0; > > > + sio->len = 0; > > > } > > > sio->bvec[sio->pages].bv_page = page; > > > - sio->bvec[sio->pages].bv_len = PAGE_SIZE; > > > + sio->bvec[sio->pages].bv_len = thp_size(page); > > > sio->bvec[sio->pages].bv_offset = 0; > > > + sio->len += thp_size(page); > > > sio->pages += 1; > > > if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) { > > > swap_read_unplug(sio); > > > @@ -521,8 +525,7 @@ void __swap_read_unplug(struct swap_iocb *sio) > > > struct address_space *mapping = sio->iocb.ki_filp->f_mapping; > > > int ret; > > > > > > - iov_iter_bvec(&from, READ, sio->bvec, sio->pages, > > > - PAGE_SIZE * sio->pages); > > > + iov_iter_bvec(&from, READ, sio->bvec, sio->pages, sio->len); > > > ret = mapping->a_ops->swap_rw(&sio->iocb, &from); > > > if (ret != -EIOCBQUEUED) > > > sio_read_complete(&sio->iocb, ret); > > > > > > > > > > >