From nobody Fri Oct 3 20:23:03 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3865F27814F for ; Mon, 25 Aug 2025 13:50:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756129828; cv=none; b=rZ+fFj5b/8RcwdRcBJRQRfFP55WjZjAlC84U27Wd35UPnTrZZTwWLrWmAeEeDgRpioATTSDLsy3JLYsRDOQG3SnIr0ZnAtoBAfbProfEe7ocUhKoeBVmJSWiYd6qsJTEvwx/R/uKDpqaY47vh+pNBQRN6O3jradP4VMGAbOMiYA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756129828; c=relaxed/simple; bh=zwwHdWEZRsSquHKGP/iohqVzGkjZqpsnxqTlCxqdA8Y=; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=WZlNcBHHcleSCen0nO5yrEassqyaOEOkwRRxuVv6MwOCouzoi2sEqPqnduscrn28HGfRN/Qjf6ZPT5Xdz5Ec1Asz+dJQAqLb6AXBAIT818Vr9SGWEWf3/mNnOQR4Iluyijj5bxDvW6v5o/8iUDCxhCFXebS5hfg/+9wFjZBvjRo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=S1QZVI7+; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="S1QZVI7+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1756129826; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type; bh=9+JM+V1hLWq1T+pNLSsHiOlhhh9GbwHAvr+HDzIv5sw=; b=S1QZVI7+nprt6D5X2APwjcH+EqX0EWdO/VWS6DXJqhgPF9wAf06rg6wYSfLYIta5K/ZK22 C3UcPbjoDJ93ndBb7/7PneclI5zz/JMbRBfb+G0qnEFel8Jfoo2zEhM+P1eMZlKvEPH11M y+ELDNKI3PC5otcT7uC4euXBrrx+riY= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-580-EI4c7fVyO1KVcZoPIPF_TA-1; Mon, 25 Aug 2025 09:50:22 -0400 X-MC-Unique: EI4c7fVyO1KVcZoPIPF_TA-1 X-Mimecast-MFC-AGG-ID: EI4c7fVyO1KVcZoPIPF_TA_1756129820 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3079718002C6; Mon, 25 Aug 2025 13:50:20 +0000 (UTC) Received: from localhost (unknown [10.22.81.168]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 82BF7195419F; Mon, 25 Aug 2025 13:50:18 +0000 (UTC) Date: Mon, 25 Aug 2025 10:50:16 -0300 From: "Luis Claudio R. Goncalves" To: Oleg Nesterov , Peter Zijlstra , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Tejun Heo , David Vernet , Barret Rhoden , Josh Don , Crystal Wood , linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Juri Lelli , Ben Segall , Dietmar Eggemann , Ingo Molnar , Mel Gorman , Valentin Schneider , Vincent Guittot , Thomas Gleixner , Wander Lairson Costa Subject: [RESEND PATCH] sched: restore the behavior of put_task_struct() for non-rt Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Commit 8671bad873eb ("sched: Do not call __put_task_struct() on rt if pi_blocked_on is set") changed the behavior of put_task_struct() unconditionally, even when PREEMPT_RT was not enabled, in clear mismatch with the commit description. Restore the previous behavior of put_task_struct() for the PREEMPT_RT disabled case. Fixes: 8671bad873eb ("sched: Do not call __put_task_struct() on rt if pi_bl= ocked_on is set") Acked-by: Oleg Nesterov Signed-off-by: Luis Claudio R. Goncalves --- Note: This patch is a fix motivated by Oleg Nesterov's question at https://lore.kernel.org/linux-rt-devel/20250728201441.GA4690@redhat.com/ diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index ea41795a352b..51678a541477 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -130,6 +133,16 @@ static inline void put_task_struct(struct task_struct = *t) if (!refcount_dec_and_test(&t->usage)) return; =20 + /* In !RT, it is always safe to call __put_task_struct(). */ + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { + static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP); + + lock_map_acquire_try(&put_task_map); + __put_task_struct(t); + lock_map_release(&put_task_map); + return; + } + /* * Under PREEMPT_RT, we can't call __put_task_struct * in atomic context because it will indirectly @@ -137,10 +150,6 @@ static inline void put_task_struct(struct task_struct = *t) * current process has a mutex enqueued (blocked on * a PI chain). * - * In !RT, it is always safe to call __put_task_struct(). - * Though, in order to simplify the code, resort to the - * deferred call too. - * * call_rcu() will schedule __put_task_struct_rcu_cb() * to be called in process context. *