From nobody Tue Dec 30 12:53:30 2025 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 75E98C2BB3F for ; Wed, 15 Nov 2023 16:21:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229999AbjKOQVJ (ORCPT ); Wed, 15 Nov 2023 11:21:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230177AbjKOQVF (ORCPT ); Wed, 15 Nov 2023 11:21:05 -0500 Received: from mail-il1-x12e.google.com (mail-il1-x12e.google.com [IPv6:2607:f8b0:4864:20::12e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23C3B1BD for ; Wed, 15 Nov 2023 08:21:00 -0800 (PST) Received: by mail-il1-x12e.google.com with SMTP id e9e14a558f8ab-357cf6725acso26707475ab.3 for ; Wed, 15 Nov 2023 08:21:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700065260; x=1700670060; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=VTFJnUE02Fl/erP4woMg7FCRUhqR44wUotjmE1ijPSg=; b=E3OXM9IscpCbdG0whh1LM+tDmt9fJlxiGMSJXfrGUPZk//C0vc/o7Noe+uY6NHW40q ltxQ0ZJBfuOCLWeZs3cs1YCfFvnI/FApGQoyXT6YvonCKuZ5Y8386X1CzDawAApBbLGn dMYsemcdeO63NIcKS83GXHvreEys9e9fTUMgQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700065260; x=1700670060; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=VTFJnUE02Fl/erP4woMg7FCRUhqR44wUotjmE1ijPSg=; b=PkusoPh01QxdoYlhMeUGyB8CFEuxquCTNge0jR69MHukGXErZqi9jnIg1xIK0MytHx VXOHnyFFoD7/avHl1gZMcvmBw63PFLwCLKWmm0zwy7wcE0TEMXH0xqAwY2rqj3RQtxV6 /pUTvxp8dPekeWPQZ2kJ+07cvzYyWvjEQPle8iMabYxPuMDmwP0aeln3Dvu0y/B7NehH r6y/7jPqXUHfXNM5rY9wt7HuUrSKodfbsfSfAoLpmbQrbD8GsVToV7/1JoNHGwBmFVwe zC4uuzXGERatDOzBdpMHgKjfR1ZTp9dET121+jZJiEG/bqhlgrcPPSF0LVwppRP9nijb Yy+Q== X-Gm-Message-State: AOJu0YwDaT8c8Bz6/KPLyY81JrwjIMFxjKGF/6ZYpbwbFstvlS9mxxD2 0yiJxWW32GisHGgM2i2ioSuUJV4wfGwphL3f5hQ= X-Google-Smtp-Source: AGHT+IEQfGCSbzgsXlVEtw+4pIN/s1f2VziN8iZBz3Kt/hFHx8nWNO7LKYqHriHT3La4Y7GhbMaaPw== X-Received: by 2002:a92:c24a:0:b0:35a:b0a5:23ab with SMTP id k10-20020a92c24a000000b0035ab0a523abmr13217526ilo.21.1700065260120; Wed, 15 Nov 2023 08:21:00 -0800 (PST) Received: from timvp-p620-9115096.bld.corp.google.com ([2620:15c:183:200:31f9:945d:f7f2:bd55]) by smtp.gmail.com with ESMTPSA id r1-20020a92c501000000b003574cad1598sm1215050ilg.33.2023.11.15.08.20.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Nov 2023 08:20:59 -0800 (PST) From: Tim Van Patten To: LKML Cc: markhas@google.com, Tim Van Patten , Johannes Weiner , Tejun Heo , Zefan Li , cgroups@vger.kernel.org Subject: [PATCH] cgroup_freezer: cgroup_freezing: Check if not frozen Date: Wed, 15 Nov 2023 09:20:43 -0700 Message-ID: <20231115162054.2896748-1-timvp@chromium.org> X-Mailer: git-send-email 2.43.0.rc0.421.g78406f8d94-goog MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Tim Van Patten __thaw_task() was recently updated to warn if the task being thawed was part of a freezer cgroup that is still currently freezing: void __thaw_task(struct task_struct *p) { ... if (WARN_ON_ONCE(freezing(p))) goto unlock; This has exposed a bug in cgroup1 freezing where when CGROUP_FROZEN is asserted, the CGROUP_FREEZING bits are not also cleared at the same time. Meaning, when a cgroup is marked FROZEN it continues to be marked FREEZING as well. This causes the WARNING to trigger, because cgroup_freezing() thinks the cgroup is still freezing. There are two ways to fix this: 1. Whenever FROZEN is set, clear FREEZING for the cgroup and all children cgroups. 2. Update cgroup_freezing() to also verify that FROZEN is not set. This patch implements option (2), since it's smaller and more straightforward. Signed-off-by: Tim Van Patten Tested-by: Mark Hasemeyer --- kernel/cgroup/legacy_freezer.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/legacy_freezer.c b/kernel/cgroup/legacy_freezer.c index 122dacb3a443..66d1708042a7 100644 --- a/kernel/cgroup/legacy_freezer.c +++ b/kernel/cgroup/legacy_freezer.c @@ -66,9 +66,15 @@ static struct freezer *parent_freezer(struct freezer *fr= eezer) bool cgroup_freezing(struct task_struct *task) { bool ret; + unsigned int state; =20 rcu_read_lock(); - ret =3D task_freezer(task)->state & CGROUP_FREEZING; + /* Check if the cgroup is still FREEZING, but not FROZEN. The extra + * !FROZEN check is required, because the FREEZING bit is not cleared + * when the state FROZEN is reached. + */ + state =3D task_freezer(task)->state; + ret =3D (state & CGROUP_FREEZING) && !(state & CGROUP_FROZEN); rcu_read_unlock(); =20 return ret; --=20 2.43.0.rc0.421.g78406f8d94-goog