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 X-Spam-Level: X-Spam-Status: No, score=-13.8 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 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 C4396C433ED for ; Mon, 17 May 2021 18:36:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 982DE60FD9 for ; Mon, 17 May 2021 18:36:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235417AbhEQSiN (ORCPT ); Mon, 17 May 2021 14:38:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230192AbhEQSiK (ORCPT ); Mon, 17 May 2021 14:38:10 -0400 Received: from mail-qk1-x731.google.com (mail-qk1-x731.google.com [IPv6:2607:f8b0:4864:20::731]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66961C061573 for ; Mon, 17 May 2021 11:36:53 -0700 (PDT) Received: by mail-qk1-x731.google.com with SMTP id q10so6775579qkc.5 for ; Mon, 17 May 2021 11:36:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=xDXZeUPt5o63e3EAMlrrPUKhIs+5nbG9PoLpAGN3bQY=; b=jd1bmNkpPE7ZLUvzEQY1VM5qpnYhmODjrvBEhSADdrN37zdq+gZcxuVS1kOjhe1iRZ l7z9RMMz+2aP/oGTmB4kgjRxm5yJ9sltqK+WadRv4dcnJMFLs08BtKu4++uZWG3TZhJd H6xCj/zOcdA5m94vyKp3V9W3Tt1u5+KLmivr7FLDAYZ3+86bXWG0PJSYIQazZgMlN/LW 0tSPdc/GICgCuDmSOcHh4IxUEYB5Wns09K6BzcB85NisvW0H/raUNUiijj9W3mX2GTh7 t8r9ikIvfqbMWtV59CPkUFicTydhzERtOsjBqefQDEQxbCT019whmstmJmk3mPnyNxkX Zs2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=xDXZeUPt5o63e3EAMlrrPUKhIs+5nbG9PoLpAGN3bQY=; b=MBwHrc9Yt/CX6lw/onDC6xOE9f3cZx71gxoQKL/3fJFHsF4gkWNFG+ewI9d700TZdX yih4RsTr0qH+xh3QayDAlJuZidDrcazNjUKMLJNpQ+5ZXIrBd+byU2vbCCunT/7LqWYL NgOolS3sEsBJi2HshKKLQGFuKyJdaff/o82NVp7vZtKyyGiALMmC/dckcKJSVahg6hTe CayiISmrih+qiKPLC2Iqk+Azery5UpUbxOqpnkNupUCqYL/nl3t7QvnvKT6o7i1YyiyW HRtSf/A2lVNs+7k1w7ki/Yoz66zKtFG+ZsMj+yo8/Sc9Y98fTS8tVtB+tlIXwHZS6jCu 3xQg== X-Gm-Message-State: AOAM531iKiHLm8iZATdgV9e+uM2+lu1JsPqKnBvPP7Gvi1o/JRnTsB3n XPry36XOJDydmd+Du1HXBoUC7Q== X-Google-Smtp-Source: ABdhPJxmJxfbXot8x9jqLb8m9kN9kDtpj8UeFDTbz81YB77VEsAqmcodHIPymeCiCHVKo/2lrpAxHQ== X-Received: by 2002:ae9:e919:: with SMTP id x25mr1251594qkf.232.1621276612686; Mon, 17 May 2021 11:36:52 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:8d28]) by smtp.gmail.com with ESMTPSA id z11sm10986776qto.95.2021.05.17.11.36.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 May 2021 11:36:52 -0700 (PDT) Date: Mon, 17 May 2021 14:36:50 -0400 From: Johannes Weiner To: Huangzhaoyang Cc: Zhaoyang Huang , Ziwei Dai , Ke Wang , Suren Baghdasaryan , linux-kernel@vger.kernel.org Subject: Re: [[RFC]PATCH] psi: fix race between psi_trigger_create and psimon Message-ID: References: <1621242249-8314-1-git-send-email-huangzhaoyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1621242249-8314-1-git-send-email-huangzhaoyang@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org CC Suren On Mon, May 17, 2021 at 05:04:09PM +0800, Huangzhaoyang wrote: > From: Zhaoyang Huang > > Race detected between psimon_new and psimon_old as shown below, which > cause panic by accessing invalid psi_system->poll_wait->wait_queue_entry > and psi_system->poll_timer->entry->next. It is not necessary to reinit > resource of psi_system when psi_trigger_create. > > psi_trigger_create psimon_new psimon_old > init_waitqueue_head finish_wait > spin_lock(lock_old) > spin_lock_init(lock_new) > wake_up_process(psimon_new) > > finish_wait > spin_lock(lock_new) > list_del list_del > > Signed-off-by: ziwei.dai > Signed-off-by: ke.wang > Signed-off-by: Zhaoyang Huang > --- > kernel/sched/psi.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c > index cc25a3c..d00e585 100644 > --- a/kernel/sched/psi.c > +++ b/kernel/sched/psi.c > @@ -182,6 +182,8 @@ struct psi_group psi_system = { > > static void psi_avgs_work(struct work_struct *work); > > +static void poll_timer_fn(struct timer_list *t); > + > static void group_init(struct psi_group *group) > { > int cpu; > @@ -201,6 +203,8 @@ static void group_init(struct psi_group *group) > memset(group->polling_total, 0, sizeof(group->polling_total)); > group->polling_next_update = ULLONG_MAX; > group->polling_until = 0; > + init_waitqueue_head(&group->poll_wait); > + timer_setup(&group->poll_timer, poll_timer_fn, 0); This makes sense. > rcu_assign_pointer(group->poll_task, NULL); > } > > @@ -1157,7 +1161,6 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, > return ERR_CAST(task); > } > atomic_set(&group->poll_wakeup, 0); > - init_waitqueue_head(&group->poll_wait); > wake_up_process(task); > timer_setup(&group->poll_timer, poll_timer_fn, 0); This looks now unncessary? > rcu_assign_pointer(group->poll_task, task); > @@ -1233,7 +1236,6 @@ static void psi_trigger_destroy(struct kref *ref) > * But it might have been already scheduled before > * that - deschedule it cleanly before destroying it. > */ > - del_timer_sync(&group->poll_timer); And this looks wrong. Did you mean to delete the timer_setup() line instead?