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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 9DC5CC67863 for ; Thu, 18 Oct 2018 20:24:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F70E2145D for ; Thu, 18 Oct 2018 20:24:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toxicpanda-com.20150623.gappssmtp.com header.i=@toxicpanda-com.20150623.gappssmtp.com header.b="nT39Y/I3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F70E2145D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=toxicpanda.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727166AbeJSE0Q (ORCPT ); Fri, 19 Oct 2018 00:26:16 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:45337 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726562AbeJSE0P (ORCPT ); Fri, 19 Oct 2018 00:26:15 -0400 Received: by mail-qt1-f196.google.com with SMTP id e10-v6so35854636qtq.12 for ; Thu, 18 Oct 2018 13:23:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=from:to:subject:date:message-id:in-reply-to:references; bh=hGTHjPlv3HOhn5TB2Ipo9k7piqoFCis94sG3VyiCA5k=; b=nT39Y/I3v+R7DJdgx+w05J/2Y+m3MDiWnk1nL7t4/7+CM7XiPVYhj3l2z9w5ARkDux SFUAlxO8JdvxirqMmPZTGRvyXzf/F1gf27MRw/gbTBAQeYjmUZFp91y8pO5oLUh9paj3 4Mg/pRVwYZoQ+VQkybYJi/38gUFMY+wk3NRr5cxlCblJoaTeZtKimCERIJSs/YPNhsQw Yj4RoxkBR9WrEqUR55b9S912+TOdECaPpCVpoCo8EWzHw4uHPszCM0G+xVZCMip+v2kq ZdJGjXwHzmN0UQp67pYVQo+e1u4jv2h70jkcXBy0hGhY7XII8xnk9N7bqGUI5ApV7HA9 xy2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references; bh=hGTHjPlv3HOhn5TB2Ipo9k7piqoFCis94sG3VyiCA5k=; b=l68ycRe+9KEZC0uRBwflzlx5cb0zAIQUPwMphMMdvqgDCjLe6sL3yRnbPjNv9u50Xo COx0pbNu/OLqNSefVOjzgr7a8qtmxY9i4XIQH5OMkhht7JcQXEq314wBFOA1UBD31CtR UXISZBivu2mL5512D80GC/Qx8fWclEOWEAnbOedvxdfWtMgTlqQrc2FVslJpgc7kckeB dgY5RTLFf8PiTTFOqqr0/Q/PXOoFJGShcOF40TMD8yLKNV/rHQI4BMiO8+/bx+c3Y/xn RznIUN/kEU7XSG3bxOFyhYxeI2soIuzXEpxlj6v8CRqCUGoUlvoP7kuQeu4Opg1TDfK/ zglA== X-Gm-Message-State: ABuFfog/hvnVTJUa9CGm6D+m++XnQXtJQ3wTrQG54qUQ83XpAZLdTqtT 9daztmfr0rroLBtF90dMXhQYOg== X-Google-Smtp-Source: ACcGV60ajb9VJhgqek0PPLPRGAIgXrsXiS83GVhmSwgELdoGf1qud/rSb0MUwUUr9Cw3VlbImR7Ugg== X-Received: by 2002:a0c:b137:: with SMTP id q52mr11208025qvc.58.1539894214457; Thu, 18 Oct 2018 13:23:34 -0700 (PDT) Received: from localhost ([107.15.81.208]) by smtp.gmail.com with ESMTPSA id i79-v6sm14094657qke.17.2018.10.18.13.23.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 18 Oct 2018 13:23:33 -0700 (PDT) From: Josef Bacik To: kernel-team@fb.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, tj@kernel.org, david@fromorbit.com, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, riel@fb.com, linux-mm@kvack.org Subject: [PATCH 4/7] mm: use the cached page for filemap_fault Date: Thu, 18 Oct 2018 16:23:15 -0400 Message-Id: <20181018202318.9131-5-josef@toxicpanda.com> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20181018202318.9131-1-josef@toxicpanda.com> References: <20181018202318.9131-1-josef@toxicpanda.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we drop the mmap_sem we have to redo the vma lookup which requires redoing the fault handler. Chances are we will just come back to the same page, so save this page in our vmf->cached_page and reuse it in the next loop through the fault handler. Signed-off-by: Josef Bacik --- mm/filemap.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 65395ee132a0..5212ab637832 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2530,13 +2530,38 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) pgoff_t offset = vmf->pgoff; int flags = vmf->flags; pgoff_t max_off; - struct page *page; + struct page *page = NULL; + struct page *cached_page = vmf->cached_page; vm_fault_t ret = 0; max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); if (unlikely(offset >= max_off)) return VM_FAULT_SIGBUS; + /* + * We may have read in the page already and have a page from an earlier + * loop. If so we need to see if this page is still valid, and if not + * do the whole dance over again. + */ + if (cached_page) { + if (flags & FAULT_FLAG_KILLABLE) { + error = lock_page_killable(cached_page); + if (error) { + up_read(&mm->mmap_sem); + goto out_retry; + } + } else + lock_page(cached_page); + vmf->cached_page = NULL; + if (cached_page->mapping == mapping && + cached_page->index == offset) { + page = cached_page; + goto have_cached_page; + } + unlock_page(cached_page); + put_page(cached_page); + } + /* * Do we have something in the page cache already? */ @@ -2587,6 +2612,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) put_page(page); goto retry_find; } +have_cached_page: VM_BUG_ON_PAGE(page->index != offset, page); /* @@ -2677,7 +2703,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) if (fpin) fput(fpin); if (page) - put_page(page); + vmf->cached_page = page; return ret | VM_FAULT_RETRY; } EXPORT_SYMBOL(filemap_fault); -- 2.14.3