From patchwork Wed Apr 7 01:44:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michel Lespinasse X-Patchwork-Id: 12186481 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=-13.8 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,UNWANTED_LANGUAGE_BODY, URIBL_BLOCKED,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 D1978C43460 for ; Wed, 7 Apr 2021 01:46:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7EF5F61165 for ; Wed, 7 Apr 2021 01:46:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7EF5F61165 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=lespinasse.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2450F8E0008; Tue, 6 Apr 2021 21:45:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5641B8E0013; Tue, 6 Apr 2021 21:45:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 42D988E0012; Tue, 6 Apr 2021 21:45:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0041.hostedemail.com [216.40.44.41]) by kanga.kvack.org (Postfix) with ESMTP id C9FAE8D000C for ; Tue, 6 Apr 2021 21:45:08 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8C2C86C2F for ; Wed, 7 Apr 2021 01:45:08 +0000 (UTC) X-FDA: 78003877896.20.BF8C7A0 Received: from server.lespinasse.org (server.lespinasse.org [63.205.204.226]) by imf17.hostedemail.com (Postfix) with ESMTP id 824A840002CF for ; Wed, 7 Apr 2021 01:45:06 +0000 (UTC) DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=lespinasse.org; i=@lespinasse.org; q=dns/txt; s=srv-11-ed; t=1617759903; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : from; bh=2b40fHZOymmhGJxI0G3GGByTYESRQj8MqQXnbVkgf4k=; b=rXM4NzWSzWcgaoFSX84ZUtXtVSmb0ie4Dv/LeHHqXZgS+oSmJL5ZAZWqJxRFBNKpvDTpg /KFSj6xdLkApTLYDg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lespinasse.org; i=@lespinasse.org; q=dns/txt; s=srv-11-rsa; t=1617759903; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : from; bh=2b40fHZOymmhGJxI0G3GGByTYESRQj8MqQXnbVkgf4k=; b=E6lEMweRaJ8ikAuN3ggqOm/+deuwAvAe4/+tRAmlHrlqKXySUlRlCu4mnDsXMira74kqQ 8QZkmrF5S2O6hHxn043dWyoXl1FkgpudzojALP7Fr/J+FQsR/a1Bq9ZafuU6i9afr9EhOXC Q/BIDlLVeje/Sd6UVGnP17Brbqh1c6PHPBbTxiWFAVICNivtw7Nj1qfKu4aEtzkKi3wWNX3 eyfrL1t+Ac82SzSaY0g93MQ43iLQLa2ruFPUKGXDb1s81im1za7WVMUbqGQ4JJp2HjRGcJD xdYooB7fsmS6ZvdnMWfRTCRi226A6A8mLMHOLViq2SWrn32gTzX5x84wB82Q== Received: from zeus.lespinasse.org (zeus.lespinasse.org [10.0.0.150]) by server.lespinasse.org (Postfix) with ESMTPS id 4B721160565; Tue, 6 Apr 2021 18:45:03 -0700 (PDT) Received: by zeus.lespinasse.org (Postfix, from userid 1000) id 3B94A19F31D; Tue, 6 Apr 2021 18:45:03 -0700 (PDT) From: Michel Lespinasse To: Linux-MM Cc: Laurent Dufour , Peter Zijlstra , Michal Hocko , Matthew Wilcox , Rik van Riel , Paul McKenney , Andrew Morton , Suren Baghdasaryan , Joel Fernandes , Rom Lemarchand , Linux-Kernel , Michel Lespinasse Subject: [RFC PATCH 31/37] ext4: implement speculative fault handling Date: Tue, 6 Apr 2021 18:44:56 -0700 Message-Id: <20210407014502.24091-32-michel@lespinasse.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210407014502.24091-1-michel@lespinasse.org> References: <20210407014502.24091-1-michel@lespinasse.org> MIME-Version: 1.0 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 824A840002CF X-Stat-Signature: eesmsg1mconkr616i4g3c9erg44i7b96 Received-SPF: none (lespinasse.org>: No applicable sender policy available) receiver=imf17; identity=mailfrom; envelope-from=""; helo=server.lespinasse.org; client-ip=63.205.204.226 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617759906-156649 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: We just need to make sure ext4_filemap_fault() doesn't block in the speculative case as it is called with an rcu read lock held. Signed-off-by: Michel Lespinasse --- fs/ext4/file.c | 1 + fs/ext4/inode.c | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 194f5d00fa32..546b9d4aa9d7 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -742,6 +742,7 @@ static const struct vm_operations_struct ext4_file_vm_ops = { .fault = ext4_filemap_fault, .map_pages = filemap_map_pages, .page_mkwrite = ext4_page_mkwrite, + .speculative = true, }; static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 0948a43f1b3d..370484403c71 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -6192,7 +6192,12 @@ vm_fault_t ext4_filemap_fault(struct vm_fault *vmf) struct inode *inode = file_inode(vmf->vma->vm_file); vm_fault_t ret; - down_read(&EXT4_I(inode)->i_mmap_sem); + if (vmf->flags & FAULT_FLAG_SPECULATIVE) { + if (!down_read_trylock(&EXT4_I(inode)->i_mmap_sem)) + return VM_FAULT_RETRY; + } else { + down_read(&EXT4_I(inode)->i_mmap_sem); + } ret = filemap_fault(vmf); up_read(&EXT4_I(inode)->i_mmap_sem);