From patchwork Fri Jan 20 15:02:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wander Lairson Costa X-Patchwork-Id: 46410 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:eb09:0:0:0:0:0 with SMTP id s9csp257885wrn; Fri, 20 Jan 2023 07:19:59 -0800 (PST) X-Google-Smtp-Source: AMrXdXt3BzjXpg454kvH2kblNZSLLa8DCJurbpecuGgqHEskOVYMBD8kfViJx2lduWwAj7Miqrfh X-Received: by 2002:a17:90a:4fa4:b0:226:f7d7:50f4 with SMTP id q33-20020a17090a4fa400b00226f7d750f4mr38574697pjh.21.1674227998763; Fri, 20 Jan 2023 07:19:58 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1674227998; cv=none; d=google.com; s=arc-20160816; b=ARB0UKvPGoZzFD3KLS4M8SvCqvLIQ9hs/PBTRF9rsa+zAOrRMUWQWXRIypN4tdv3GZ rgR6ud1a6ZI3uLEYrBaTP+H/A4SyATmqXGBp8vVa+W9lBu/3C8ApBe7b0gswy78FNalq IJbjYfuFfhvjSfd6V0RuN0o/S+X6hDRBL+kreoemBKbOe1Yh9PDWc/EUcPg4SQcLfTSq hMjTcWE5saDMjYWwzTfMCK/tKrWGTuCr+pSHivIusmMOhjbfJbkF4t6jJoo7bWCmpLVB kRKmSyR1EzDC11TUSHxhbToJIxCMEF/pvxTIXikzXNZF2KrxN+RFPZ5b3QKUlE83MJwk xsGA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:to:from :dkim-signature; bh=F1TJWHWdZqDFCr8xEA0m937H+WTiVZmJanYCSnQgjrk=; b=YftExW/QxThO1TGwiLNRGSVXqGy8JiKI9Wb8VhiMMiA/bM1z6aba8b7QKYBqO9ZcCo WljS6Ns2QHkPRPongnfGrWEPD5Bax3CK7TRFwfrhChbBJwBlqzZ4p7ScKIChuJBLlLek UglEf41Dn/iyoAHtfSA+IgB2V/cxC1dYKfaNTAFLXnm8qpJePaTqndN+0BKoMER2FuTf dhRlUc1wz/YJvocamBV1Li2Qk5QNMtLY6VH8bauaVsYRE4iTZNbLs0WwFfLvIa2By7W3 88uoXkYLKjdkhLxgKeD1Eu5ir+9sCWdGwF1Y21kp87y0+vcxOFC9C/mVSz882szG7n/g oqgA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=aBw3t80S; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id c15-20020a17090a4d0f00b00218b7ae4defsi2508883pjg.134.2023.01.20.07.19.46; Fri, 20 Jan 2023 07:19:58 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=aBw3t80S; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229742AbjATPEj (ORCPT + 99 others); Fri, 20 Jan 2023 10:04:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230429AbjATPEa (ORCPT ); Fri, 20 Jan 2023 10:04:30 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80FDB81013 for ; Fri, 20 Jan 2023 07:03:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674227022; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=F1TJWHWdZqDFCr8xEA0m937H+WTiVZmJanYCSnQgjrk=; b=aBw3t80SCMtSlaTEoenyoVBHtZz+Vxk9rFf7DH2Lv66xzogqsM5cjEBtW+rvh1kRa1g1LR 3rOuEySgjIG/wSgvGemc1SpdTW3z11BQLYtsXZdkRlN+T3LwK7Tktmb7AINbZ8PTqkPohB i9grLRDACUvJucBwrv1JbVJf9ZE8RmM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-16-XksM0rtCN-K57tGpGanOQQ-1; Fri, 20 Jan 2023 10:03:35 -0500 X-MC-Unique: XksM0rtCN-K57tGpGanOQQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 18E4F181E3EE; Fri, 20 Jan 2023 15:03:34 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.32.187]) by smtp.corp.redhat.com (Postfix) with ESMTP id 44B13492B02; Fri, 20 Jan 2023 15:03:29 +0000 (UTC) From: Wander Lairson Costa To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , "Eric W. Biederman" , Stafford Horne , Guo Ren , Kefeng Wang , Oleg Nesterov , Wander Lairson Costa , Andrew Morton , Thomas Gleixner , Sebastian Andrzej Siewior , Andy Lutomirski , "Liam R. Howlett" , Fenghua Yu , Andrei Vagin , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 3/4] sched/rt: use put_task_struct_atomic_safe() to avoid potential splat Date: Fri, 20 Jan 2023 12:02:41 -0300 Message-Id: <20230120150246.20797-4-wander@redhat.com> In-Reply-To: <20230120150246.20797-1-wander@redhat.com> References: <20230120150246.20797-1-wander@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1755555298193862463?= X-GMAIL-MSGID: =?utf-8?q?1755555298193862463?= rto_push_irq_work_func() is called in hardirq context, and it calls push_rt_task(), which calls put_task_struct(). If the kernel is compiled with PREEMPT_RT and put_task_struct() reaches zero usage count, it triggers a splat because __put_task_struct() indirectly acquires sleeping locks. The put_task_struct() call pairs with an earlier get_task_struct(), which makes the probability of the usage count reaches zero pretty low. In any case, let's play safe and use the atomic safe version. Signed-off-by: Wander Lairson Costa Cc: Thomas Gleixner Reviewed-by: Steven Rostedt (Google) --- kernel/sched/rt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index ed2a47e4ddae..30a4e9607bec 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2147,7 +2147,7 @@ static int push_rt_task(struct rq *rq, bool pull) /* * Something has shifted, try again. */ - put_task_struct(next_task); + put_task_struct_atomic_safe(next_task); next_task = task; goto retry; } @@ -2160,7 +2160,7 @@ static int push_rt_task(struct rq *rq, bool pull) double_unlock_balance(rq, lowest_rq); out: - put_task_struct(next_task); + put_task_struct_atomic_safe(next_task); return ret; }