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 36C4EC433FE for ; Fri, 29 Apr 2022 08:13:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9AB396B0071; Fri, 29 Apr 2022 04:13:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 95BF16B0073; Fri, 29 Apr 2022 04:13:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 848C46B0074; Fri, 29 Apr 2022 04:13:45 -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 750916B0071 for ; Fri, 29 Apr 2022 04:13:45 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 2AD8C26C07 for ; Fri, 29 Apr 2022 08:13:45 +0000 (UTC) X-FDA: 79409202810.31.3A56C04 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf25.hostedemail.com (Postfix) with ESMTP id 9E580A0076 for ; Fri, 29 Apr 2022 08:13:34 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KqQGr35h0zhYcy; Fri, 29 Apr 2022 16:13:24 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 29 Apr 2022 16:13:39 +0800 Subject: Re: [PATCH 1/2] MM: handle THP in swap_*page_fs() To: NeilBrown , Andrew Morton CC: Geert Uytterhoeven , Christoph Hellwig , , , References: <165119280115.15698.2629172320052218921.stgit@noble.brown> <165119301488.15698.9457662928942765453.stgit@noble.brown> From: Miaohe Lin Message-ID: Date: Fri, 29 Apr 2022 16:13:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <165119301488.15698.9457662928942765453.stgit@noble.brown> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 9E580A0076 X-Stat-Signature: 9nnhzhc8rbs5wj66pjbpiq1jsj4gf8yo Authentication-Results: imf25.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf25.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1651220014-505980 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 2022/4/29 8:43, 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". > > 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) The patch looks good to me. Thanks! But we might need use count_swpout_vm_event in sio_write_complete. THP_SWPOUT should be accounted too. And count_vm_events(PSWPOUT, sio->pages) doesn't account the right number of pages now. Maybe sio_read_complete also needs this fix. Or am I miss something? Thanks! > 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); > > > . >