From patchwork Mon May 17 09:55:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yongji Xie X-Patchwork-Id: 12261401 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,URIBL_BLOCKED,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 BAE2DC433B4 for ; Mon, 17 May 2021 09:56:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E93D61029 for ; Mon, 17 May 2021 09:56:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236234AbhEQJ5p (ORCPT ); Mon, 17 May 2021 05:57:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236238AbhEQJ5Z (ORCPT ); Mon, 17 May 2021 05:57:25 -0400 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2B90C061342 for ; Mon, 17 May 2021 02:56:08 -0700 (PDT) Received: by mail-pf1-x432.google.com with SMTP id d16so4554363pfn.12 for ; Mon, 17 May 2021 02:56:08 -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=b7apvPbQfTG1FYg2uNsocmvMG/QdC7c4RuzNmrGKxtc=; b=lXRHbHSIsb1KADw2tX2zKstf7SBlVEY4DtJnDMFT3EHKIWMje067JnmjgrkNReUxPn I0z2aIAyJGaL9m4k2OpOD29iaKpNcW4xfR7d14dIuNrPK0hQOvA8kl9rxSPc6f69Mm6p R0F2LeWEZA0PPqOKTYoBW3+9nQSkYxFKNz5WUEn2djE6598CZ00wKdFzTggwdy8opqtd +LicmUYFz5R2JqJ3r3lQ/vDv0gKToNlIKrKEdVnqYs5TGR2EJsU3XPEKupH3aVQAL9FE 3exCZ90aL2Cb7tTVwr9v8iYtnhbog2Qo9fEaKaJOYYh61niFj77C/LAndUBtJYYe86bM nS5w== 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=b7apvPbQfTG1FYg2uNsocmvMG/QdC7c4RuzNmrGKxtc=; b=n+3wMNEJCO5MEZ4ONNQC13+LftW/Lp6uRUkx7WWPpPOG+Wy4u5ftknTVpZmW2TKkls cV8sStrnYJjDfH71U0KandOtJ1NpC9Dv1Po97uehyWsj2hERuOFZ7/YRlK1O8yG6XMod ovwcRDa1v1Oqlfm8ADh9VvnHXtXzFRtTPskLVqRNZ9XHVSVoRyqOLqAb8bLrfKuk5RRN lbBYGbkx8Z0Ykx+H9bxYj0TtWt3aNZZ9Ei6TFoY3v74TqmZ3BEWE/rjGbPkikTF/H2Cd T8+W/XW2CQ3KQ58gLH3+Kw/1UIHh0SCdMuHIfryelDFlBomqmKLMgroM1DkjdKJfVPAZ 6RMw== X-Gm-Message-State: AOAM531odhw2j3/utFDz573a4yurWjfSFUYTz3PUscZT+d8DdBPIX6JY pT11sDblPHZ7aKWjYvhp2zdM X-Google-Smtp-Source: ABdhPJwO1N2BTDcGIAdEBE1GwKwtKYl5hxzWv7M8ro+LthKkIXN/GYpMnfpVi6rAWoY6mIGZm1TWzA== X-Received: by 2002:a63:741e:: with SMTP id p30mr61016414pgc.68.1621245368362; Mon, 17 May 2021 02:56:08 -0700 (PDT) Received: from localhost ([139.177.225.253]) by smtp.gmail.com with ESMTPSA id 24sm10063099pgz.77.2021.05.17.02.56.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 May 2021 02:56:07 -0700 (PDT) From: Xie Yongji To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, sgarzare@redhat.com, parav@nvidia.com, hch@infradead.org, christian.brauner@canonical.com, 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, joro@8bytes.org Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 03/12] eventfd: Increase the recursion depth of eventfd_signal() Date: Mon, 17 May 2021 17:55:04 +0800 Message-Id: <20210517095513.850-4-xieyongji@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210517095513.850-1-xieyongji@bytedance.com> References: <20210517095513.850-1-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] Signed-off-by: Xie Yongji Acked-by: Jason Wang --- 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 */