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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C9054C79F99 for ; Mon, 7 Sep 2026 21:55:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 96C3D6B008A; Mon, 7 Sep 2026 17:55:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 944A96B008C; Mon, 7 Sep 2026 17:55:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 80D8B6B0092; Mon, 7 Sep 2026 17:55:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 4F1AB6B008A for ; Mon, 7 Sep 2026 17:55:16 -0400 (EDT) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id D87C8802A5 for ; Mon, 7 Sep 2026 21:55:15 +0000 (UTC) X-FDA: 85188322590.26.2851C31 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf14.hostedemail.com (Postfix) with ESMTP id A00F6100003 for ; Mon, 7 Sep 2026 21:55:13 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eJdlAp9p; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf14.hostedemail.com: domain of oleg@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=oleg@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788818113; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=U5vbt3dDTcq0wdPHap0JtL9B1dVtnkBH7soBmqKWLIw=; b=fnqJ9VLxDIiGcCaMLWctWFVhkZG7ArvOxBDKDWiDAodA4na8rxoAv+EgQwVMPla5U1IIkX IzSB+FB7J/FvVA7BQECuy3qXNEnj4S6eIaidyntmf+/ejix0ZNJgzPWy9s4biPCATq9Coh 3P4WQWeGKeOhBldZxHBsbtP4OBwv3r4= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eJdlAp9p; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf14.hostedemail.com: domain of oleg@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=oleg@redhat.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788818113; b=m3VW+TYQQbHR9FXQ1lt6tsUUDLLq0n9AynRxV2hOMQYHz6U6B4+gDasL2WEbkWxaD1u7Fp FWgn5bblo8IAzx3DeZ9ZVQpLOmzU7QFHaYdiwXLL8CHCntX1oTFbrjlEk9yOK55lzQoGTl FjY7QTjpJGcJoDFnKsTZhHcDlZvrQw8= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788818113; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U5vbt3dDTcq0wdPHap0JtL9B1dVtnkBH7soBmqKWLIw=; b=eJdlAp9pL8/AkZmsFNcDcH488lEHuOZRyL7mwqYn0eZPYi1qam0Eo5uSt7A0C0yFVtqPnK pHcZQYNQA69oXFIBBbmkulB3dWcd7DCMt694WaME4MMHyWMAKvUTT7kpBgJmQsyfsbK0Sb 0h+Os93nKe1btBgHBM87lpYceJCgUDU= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-258-76hC-MuePVOa3a9FHcteLQ-1; Mon, 07 Sep 2026 17:55:09 -0400 X-MC-Unique: 76hC-MuePVOa3a9FHcteLQ-1 X-Mimecast-MFC-AGG-ID: 76hC-MuePVOa3a9FHcteLQ_1788818103 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 91EAD1956072; Mon, 7 Sep 2026 21:55:00 +0000 (UTC) Received: from fedora (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 8E52D1800257; Mon, 7 Sep 2026 21:54:42 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 7 Sep 2026 23:55:00 +0200 (CEST) Date: Mon, 7 Sep 2026 23:54:41 +0200 From: Oleg Nesterov To: Gregory Price Cc: Ye Liu , Thomas Gleixner , Peter Zijlstra , "Rafael J. Wysocki" , Andrew Morton , Ingo Molnar , Will Deacon , Boqun Feng , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Juri Lelli , Vincent Guittot , Steven Rostedt , Masami Hiramatsu , Josh Poimboeuf , Ye Liu , Michal Hocko , mic@digikod.net, david@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, gnoack3000@gmail.com, ljs@kernel.org, sj@kernel.org, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, tony.luck@intel.com, reinette.chatre@intel.com, x86@kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, pavel@kernel.org, lance.yang@linux.dev, pmladek@suse.com, longman@redhat.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, mark.rutland@arm.com, Dave.Martin@arm.com, james.morse@arm.com, babu.moger@amd.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rcu@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v2 5/8] kernel: convert process/thread iterators to for_each_*_rculock Message-ID: References: <20260907081334.1152889-1-ye.liu@linux.dev> <20260907081334.1152889-6-ye.liu@linux.dev> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: KuTJyUN-BdeD7s2OgomzeZAazGGqfpu-AaEFYHirQPY_1788818103 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Stat-Signature: qt51497c4e9mjzw9fqd6dymoecmfhopk X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: A00F6100003 X-Rspam-User: X-HE-Tag: 1788818113-72610 X-HE-Meta: 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 I58P4UBT SfTav8dvSROycvvQL2HrZi3lCOjIgJ8w5kuk3gfaWdVoJEG2PIekGIlOuarG3mltIdVaWQXeTGNHAMTFC07/m4fOQ134Kge/DLHD/5AQ8/p0YzlsplUNmB/T/S+u8cGx5+YsOTMv4/pdkh/AYzZ+PoK5nhE+DQKD0IFlTdwX4fpdop10W1fob2pQhizRhQRE0R+MAgPfQdiIr5ImsYTviaXmkyVMUuK+G57KOyWTHdfZpc9OVIdr8Ig5okcbFr0w8Cm4C4DLawZnTYbg2doQCDqnaTHBJd4Ps1dqqg9ZH3RAnHkxSV0Ev4Si5E/0oMDZ4KqFYHoUOjhy5HYdIJqlJK2lFw3AjVFppf6qKxESkOyEpZ1d7p7/Q1q0uguqRiKHITYVE3Kww6vs9/hOqjq1QpDbcx8jQyrjZeh0WNtJJtfOTIsqEVaY/VjQsvTYWYBH4claK03jB+/FEg7OkcjCJsQYGfkspjRA9abIL Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/07, Gregory Price wrote: > > On Mon, Sep 07, 2026 at 07:57:15PM +0200, Oleg Nesterov wrote: > > On 09/07, Gregory Price wrote: > > > > > > On Mon, Sep 07, 2026 at 04:13:31PM +0800, Ye Liu wrote: > > > > --- a/kernel/hung_task.c > > > > +++ b/kernel/hung_task.c > > > > @@ -315,13 +315,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > > > > return; > > > > > > > > this_round_count = 0; > > > > - rcu_read_lock(); > > > > - for_each_process_thread(g, t) { > > > > + for_each_process_thread_rculock(g, t) { > > > > if (!max_count--) > > > > - goto unlock; > > > > + goto out; > > > ... snip ... > > > > - unlock: > > > > - rcu_read_unlock(); > > > > - > > > > +out: > > > > if (!this_round_count) > > > > return; > > > > > > > > > > The sunken rcu_read_lock()/unlock() + scoped_guard usage makes this goto > > > at a minimum very confusing, if not actually broken. > > > > I am afraid I misunderstood you concerns... > > > > This might be my - admittedly shallow - understanding of scoped_guard, > but does scoped guard handle goto correctly? Yes, it does, > and why it's generally discouraged to mix cleanup.h and goto. Hmm, why? I didn't know... Oleg.