From patchwork Mon Mar 15 05:37:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yongji Xie X-Patchwork-Id: 12138319 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 6AA6DC43333 for ; Mon, 15 Mar 2021 05:38:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 55A4B61574 for ; Mon, 15 Mar 2021 05:38:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230136AbhCOFiO (ORCPT ); Mon, 15 Mar 2021 01:38:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229929AbhCOFh6 (ORCPT ); Mon, 15 Mar 2021 01:37:58 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E7D52C06175F for ; Sun, 14 Mar 2021 22:37:57 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id r16so4540609pfh.10 for ; Sun, 14 Mar 2021 22:37:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=vQwyOgJ8FbVKIyGmYgv1VI8rf3/7i+776SIOH8C9h3s=; b=tKC5Kczn7W4GX2DVAtJhGQH7OZ/Y9d5HQGZokltTFvIKjewpr8wlARk9gk5FOOpdyM u6azIY9AT5RdJPG56be28vHXhQeiduc8tM0CpBk9BMSctJXkdS1HVd569aB0ftF35541 In86LSyOjqLfo31fh21uUaSqQsXVZDOp+KOKDjas7vRQjJ0ZAOsHYfW4UaNxC8Zr5gPy DLd2kiSTWjC8AqTt4t7cWjtLSMcGSs6gpn1l0Z3KGUQYnFctmVN/MM5pr8HiggThoQfi yevqx1dZqd49OTgP9EADlRkPZgMm2AfL/AO2bfmC4Zg9pPqTvDR76CiYtth8OvtWG8BW caMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=vQwyOgJ8FbVKIyGmYgv1VI8rf3/7i+776SIOH8C9h3s=; b=quWxuux0/08JucJfquc3KqBi6h1yHiVgEaWRpunEMgaZqCsaG+Ge6brE03Ue6zSYv0 1gqvAbtB1wUvhPBC+kV53Bfd4TXUZgOq9AOwd+oOv4z1QNWNNfWw8NL0zh3n4+jaBabF /DzU40boWZkXRP+o8FaGqaNeyzwxNdqYRWlq5RWw+bAoj1rCTF9FJy96KiC874rCeFgI XhLW+V9BXOc3wGTpLK+UEJ/L5CL0LBn4yoz3kI/2+m3NPugiV2pkaJPZTcJWfHHQqJ9j ivVUr2zbMQbOyVsx8VRPbmCXR63fJ2Ilz2RvPD3H75YdBaqor8eiVXSUyajCVA2X66Ys UnJQ== X-Gm-Message-State: AOAM532nuuXzlg0y9BNHm/vyAbqIkHyiNwV4fjcuoG5HUjhk47C8oemW qRsH4NOnBu5o8jJmhnD1759D X-Google-Smtp-Source: ABdhPJw90klV/lhgLs9r2kWZa9+r4MKFCLT6x38DG1GBOMIxMW2w5D3Tc5a7icPrhx3yRBOSiAwkmQ== X-Received: by 2002:a65:5cc2:: with SMTP id b2mr4878167pgt.280.1615786677555; Sun, 14 Mar 2021 22:37:57 -0700 (PDT) Received: from localhost ([139.177.225.227]) by smtp.gmail.com with ESMTPSA id u2sm9282968pjy.14.2021.03.14.22.37.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 14 Mar 2021 22:37:57 -0700 (PDT) From: Xie Yongji To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, sgarzare@redhat.com, parav@nvidia.com, bob.liu@oracle.com, hch@infradead.org, rdunlap@infradead.org, willy@infradead.org, viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org, corbet@lwn.net, mika.penttila@nextfour.com, dan.carpenter@oracle.com Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v5 02/11] eventfd: Increase the recursion depth of eventfd_signal() Date: Mon, 15 Mar 2021 13:37:12 +0800 Message-Id: <20210315053721.189-3-xieyongji@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210315053721.189-1-xieyongji@bytedance.com> References: <20210315053721.189-1-xieyongji@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Increase the recursion depth of eventfd_signal() to 1. This is the maximum recursion depth we have found so far, which can be triggered with the following call chain: kvm_io_bus_write [kvm] --> ioeventfd_write [kvm] --> eventfd_signal [eventfd] --> vhost_poll_wakeup [vhost] --> vduse_vdpa_kick_vq [vduse] --> eventfd_signal [eventfd] Acked-by: Jason Wang Signed-off-by: Xie Yongji --- fs/eventfd.c | 2 +- include/linux/eventfd.h | 5 ++++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/eventfd.c b/fs/eventfd.c index e265b6dd4f34..cc7cd1dbedd3 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -71,7 +71,7 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n) * it returns true, the eventfd_signal() call should be deferred to a * safe context. */ - if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count))) + if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count) > EFD_WAKE_DEPTH)) return 0; spin_lock_irqsave(&ctx->wqh.lock, flags); diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h index fa0a524baed0..886d99cd38ef 100644 --- a/include/linux/eventfd.h +++ b/include/linux/eventfd.h @@ -29,6 +29,9 @@ #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE) +/* Maximum recursion depth */ +#define EFD_WAKE_DEPTH 1 + struct eventfd_ctx; struct file; @@ -47,7 +50,7 @@ DECLARE_PER_CPU(int, eventfd_wake_count); static inline bool eventfd_signal_count(void) { - return this_cpu_read(eventfd_wake_count); + return this_cpu_read(eventfd_wake_count) > EFD_WAKE_DEPTH; } #else /* CONFIG_EVENTFD */