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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6F52C77B75 for ; Fri, 19 May 2023 20:55:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231442AbjESUzG (ORCPT ); Fri, 19 May 2023 16:55:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231716AbjESUyy (ORCPT ); Fri, 19 May 2023 16:54:54 -0400 Received: from mail-qt1-x82e.google.com (mail-qt1-x82e.google.com [IPv6:2607:f8b0:4864:20::82e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6A9310F3 for ; Fri, 19 May 2023 13:54:48 -0700 (PDT) Received: by mail-qt1-x82e.google.com with SMTP id d75a77b69052e-3f42b4da6e5so18279701cf.2 for ; Fri, 19 May 2023 13:54:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore.com; s=google; t=1684529688; x=1687121688; h=in-reply-to:references:subject:to:from:message-id:date:from:to:cc :subject:date:message-id:reply-to; bh=WT/C0XPR1/vAySbbcWPHa11OWVLeot7aGDtepqZ5u+E=; b=H6YvfWvKJWZorG0TGO/SFWtxWLxVj1bafOZSvZU2dPh/hje7Sxt6uCKeHTNljZzHXd kxIXT3/IePjbf7kXU/sv9SE0GN9PJjL97jqFeHH594y+RiTSY1CsvrUvgiDhmC9LJdzP CPUawAbRkVkk+qYJ7LpPaltw6wcRKXjgt3Q6sc297JUnfUOGmI22V/JinUKgnma6bmZq ratDkmaLnMk7dw4G6u4IWFcKYPX+WqlzqUF+IQF0Ng/aE7ADWI+BhyzVNxRmjH2Z4HMM JcWi8cbQ5j7y04kdBz+g95om1JzoevLGBycUMBT9x+H3NWak7dg0ntpqv9G/1Eu2lc+W 7mqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684529688; x=1687121688; h=in-reply-to:references:subject:to:from:message-id:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=WT/C0XPR1/vAySbbcWPHa11OWVLeot7aGDtepqZ5u+E=; b=KkFSCpbTHrM+r3eY3C3yBqSBVQVkw/2dbR9q7pHbkkhaoE9jptWlTSLEyo6xjl7C2v 7OWK0aHbKCS1DkYkcMDH4EUz/zrSaFfnkAaYrjx/JKE0G8UHA4IZU5Y67HlDG6C8Y260 gXHAbSuFgbj6NDNH0VTXmTKnWJ/QYonx9SN0OzluO2m3AjOo3qXwzS2VycMi4HPbytpt dwpHwWsEvxxik7yY6/j+N8AjMflKWQmc8socLyXEEYfkSmfUBLRrjX6YOpYkgUvWKzJw n2qwJWn67aGJvVMzopeYYL98yC+9D61ZZ5C0kZUbQH9C3lCZnN21Jp5LJnpdJf0TfAs+ sjjw== X-Gm-Message-State: AC+VfDz/ySS6o8UuhfzJgVcwQlSN5DvDjVNxpgJrrQSU1FOSRU6HR5wt Uutty8u1HzoRRgllAWSEQRu1 X-Google-Smtp-Source: ACHHUZ4Eb9+VnEO3olqncqK/5kIuTihkBSrRY2ybG2/tnS/lpVpz98AMcdon7Pa4MB98bZw8MRhYEg== X-Received: by 2002:a05:622a:510:b0:3e4:e641:6b1f with SMTP id l16-20020a05622a051000b003e4e6416b1fmr6106651qtx.55.1684529681813; Fri, 19 May 2023 13:54:41 -0700 (PDT) Received: from localhost (pool-108-26-161-203.bstnma.fios.verizon.net. [108.26.161.203]) by smtp.gmail.com with ESMTPSA id w24-20020a05620a149800b0074de8d07052sm1372238qkj.47.2023.05.19.13.54.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 May 2023 13:54:41 -0700 (PDT) Date: Fri, 19 May 2023 16:54:41 -0400 Message-ID: From: Paul Moore To: Eiichi Tsukata , eparis@redhat.com, linux-kernel@vger.kernel.org, audit@vger.kernel.org Subject: Re: [PATCH v2 5/5] audit: do not use exclusive wait in audit_receive() References: <20230511052116.19452-6-eiichi.tsukata@nutanix.com> In-Reply-To: <20230511052116.19452-6-eiichi.tsukata@nutanix.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On May 11, 2023 Eiichi Tsukata wrote: > > kauditd thread issues wake_up() before it goes to sleep. The wake_up() > call wakes up only one process as waiter side uses exclusive wait. > This can be problematic when there are multiple processes (one is in > audit_receive() and others are in audit_log_start()) waiting on > audit_backlog_wait queue. > > For example, if there are two processes waiting: > > Process (A): in audit_receive() > Process (B): in audit_log_start() > > And (A) is at the head of the wait queue. Then kauditd's wake_up() only > wakes up (A) leaving (B) as it is even if @audit_queue is drained. As a > result, (B) can be blocked for up to backlog_wait_time. > > To prevent the issue, use non-exclusive wait in audit_receive() so that > kauditd can wake up all waiters in audit_receive(). > > Fixes: 8f110f530635 ("audit: ensure userspace is penalized the same as the kernel when under pressure") > Signed-off-by: Eiichi Tsukata > --- > kernel/audit.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) This was also discussed in the last patchset. -- paul-moore.com