From patchwork Sun Jul 11 15:09:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 12369211 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29B3EC07E96 for ; Sun, 11 Jul 2021 15:10:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A42536115A for ; Sun, 11 Jul 2021 15:10:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A42536115A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B65196B008A; Sun, 11 Jul 2021 11:10:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B11986B0093; Sun, 11 Jul 2021 11:10:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 98AD06B008C; Sun, 11 Jul 2021 11:10:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0057.hostedemail.com [216.40.44.57]) by kanga.kvack.org (Postfix) with ESMTP id 6CD646B008A for ; Sun, 11 Jul 2021 11:10:24 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 90D9A204A1 for ; Sun, 11 Jul 2021 15:10:23 +0000 (UTC) X-FDA: 78350643126.30.0C94EE5 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf18.hostedemail.com (Postfix) with ESMTP id 0B9874002085; Sun, 11 Jul 2021 15:10:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=855AUMnreo1HN0f6x88VXU6uE3rYZIQf/z+jfpkStV8=; b=oVIZqa/cHJZKqXZURbCu4vT/My 3BjLnO4TkSqsT9gs6iXSZs8ludP41KEhRV5E8IsEhnliSztIFL3IpFtnoF5KLgWKKfArUBzubosmE rQN6FVFqnPpMJ0Gugb4rkaj3RbStL+V1/TJ0mQApGauvjMrAquxmHATfaodvJgGXrWNZvJ9WiAsdn q2N2nAdWb5ocKFZWL3YUhMKvAdc9wJCjCmKdubSAdWA1/JuiyBzqKMroaxPxefQW/vsiKTLWHbjKB otXyUSBk3qGPfV5NMqMT5cszCvX9w4DzRRsJW7zTEOdB7GtuzQhCXOwbyw9cnCcs6WUzArF6RaBjt ZU1FuerA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m2b5b-00GMAM-0h; Sun, 11 Jul 2021 15:09:54 +0000 From: "Matthew Wilcox (Oracle)" To: Jens Axboe Cc: "Matthew Wilcox (Oracle)" , io-uring@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org Subject: [PATCH 2/2] mm/filemap: Prevent waiting for memory for NOWAIT reads Date: Sun, 11 Jul 2021 16:09:27 +0100 Message-Id: <20210711150927.3898403-3-willy@infradead.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210711150927.3898403-1-willy@infradead.org> References: <20210711150927.3898403-1-willy@infradead.org> MIME-Version: 1.0 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 0B9874002085 X-Stat-Signature: yjfn5na4ooo3y9fgmo8zjuue4dufuhw6 Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b="oVIZqa/c"; dmarc=none; spf=none (imf18.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1626016222-731311 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: Readahead memory allocations won't block for much today, as they're already marked as NOFS and NORETRY, but they can still sleep, and they shouldn't if the read is marked as IOCB_NOWAIT. Clearing the DIRECT_RECLAIM flag will prevent sleeping. Signed-off-by: Matthew Wilcox (Oracle) --- mm/filemap.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index d1458ecf2f51..2be27b686518 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2435,21 +2435,27 @@ static int filemap_create_page(struct file *file, static int filemap_readahead(struct kiocb *iocb, struct file *file, struct address_space *mapping, struct page *page, - pgoff_t last_index) + pgoff_t index, pgoff_t last_index) { + DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, index); + if (iocb->ki_flags & IOCB_NOIO) return -EAGAIN; - page_cache_async_readahead(mapping, &file->f_ra, file, page, - page->index, last_index - page->index); + if (iocb->ki_flags & IOCB_NOWAIT) + ractl.gfp_flags &= ~__GFP_DIRECT_RECLAIM; + + if (page) + page_cache_async_ra(&ractl, page, last_index - index); + else + page_cache_sync_ra(&ractl, last_index - index); return 0; } static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, struct pagevec *pvec) { - struct file *filp = iocb->ki_filp; - struct address_space *mapping = filp->f_mapping; - struct file_ra_state *ra = &filp->f_ra; + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; pgoff_t index = iocb->ki_pos >> PAGE_SHIFT; pgoff_t last_index; struct page *page; @@ -2462,16 +2468,16 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, filemap_get_read_batch(mapping, index, last_index, pvec); if (!pagevec_count(pvec)) { - if (iocb->ki_flags & IOCB_NOIO) - return -EAGAIN; - page_cache_sync_readahead(mapping, ra, filp, index, - last_index - index); + err = filemap_readahead(iocb, file, mapping, NULL, index, + last_index); + if (err) + return err; filemap_get_read_batch(mapping, index, last_index, pvec); } if (!pagevec_count(pvec)) { if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ)) return -EAGAIN; - err = filemap_create_page(filp, mapping, + err = filemap_create_page(file, mapping, iocb->ki_pos >> PAGE_SHIFT, pvec); if (err == AOP_TRUNCATED_PAGE) goto retry; @@ -2480,7 +2486,8 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, page = pvec->pages[pagevec_count(pvec) - 1]; if (PageReadahead(page)) { - err = filemap_readahead(iocb, filp, mapping, page, last_index); + err = filemap_readahead(iocb, file, mapping, page, page->index, + last_index); if (err) goto err; }