From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1ABD91EE00E; Thu, 7 Nov 2024 10:23:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730975008; cv=none; b=JNpZBO9tS6cAGFOUgYj8N2HwFhdtoGVTeP8qH7kGx7k8N/AGUcddax9jNfKyfpy3leedZBnGzr7FIbtSY7mAj8i9ztqzE2rFthrQbufThAWSwQtSVzsEgPW0T6cV4Zt0guEg4ylTpwcJfGAJd2hgmLcDv3Qg85UZsgb7/NKrAPc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730975008; c=relaxed/simple; bh=TFDLa8HlOYFM/PmgkFHcp+YBi3i4we1XyQl6R3cgqjk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AKxPZ2IqRqkQLy345AhyCZkfVDNcW5kiH9wGGpsDAmCkVE6zEM8zMOMUAoD6EG+j/mfB+txZgS/aQvU5H2U9YTncd7/hKULQze5DupNi8AVR0Xfr+AotUjxRl6gh6gewQxjQpQRZO1Qqhai0dVe2FnaJQiqopYieUrlvVnJscC0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PWLJMkF4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PWLJMkF4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F833C4CED6; Thu, 7 Nov 2024 10:23:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730975006; bh=TFDLa8HlOYFM/PmgkFHcp+YBi3i4we1XyQl6R3cgqjk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PWLJMkF4VkREaKXG9X3OTXLiN1Im82ZokTh/4JheuKTSRX8WPJa5eVP33lBWui0US 4GZsGE5uTsnY9tion4Qky9G2UouKhsCaFcNPdzy0jsxxaLCtGymQfAPz3VEHX43oKh cdNeVWhh0h8+44tQvU6XVqcQ85Rc7m0+x6FCVj+aWIWI09cqoPs3U3YKLzC8sytF15 mRIZqINIJjSpw7Gz6VmpH2z7faIUPfyiDUqHojjx4zoSDDjYFMY4MqyaDJ24EZQYcx klMJUBhWoi/LVKhuFU8vCYV+OJzdRjr+F+/sSvpPJPvMNq3CGY4DZYDVbUWEZGwOfk RcSqNeGPS4ulg== Date: Thu, 7 Nov 2024 11:23:24 +0100 From: Frederic Weisbecker To: Sasha Levin Cc: stable@vger.kernel.org, bsegall@google.com, Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: FAILED: Patch "posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone" failed to apply to v4.19-stable tree Message-ID: References: <20241106021416.184155-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241106021416.184155-1-sashal@kernel.org> Le Tue, Nov 05, 2024 at 09:14:15PM -0500, Sasha Levin a écrit : > The patch below does not apply to the v4.19-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to . > > Thanks, > Sasha Please try this: --- >From ee0d95090203b7ee4cb1f29c586cd7d0dbf79fff Mon Sep 17 00:00:00 2001 From: Benjamin Segall Date: Fri, 25 Oct 2024 18:35:35 -0700 Subject: [PATCH] posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone When cloning a new thread, its posix_cputimers are not inherited, and are cleared by posix_cputimers_init(). However, this does not clear the tick dependency it creates in tsk->tick_dep_mask, and the handler does not reach the code to clear the dependency if there were no timers to begin with. Thus if a thread has a cputimer running before clone/fork, all descendants will prevent nohz_full unless they create a cputimer of their own. Fix this by entirely clearing the tick_dep_mask in copy_process(). (There is currently no inherited state that needs a tick dependency) Process-wide timers do not have this problem because fork does not copy signal_struct as a baseline, it creates one from scratch. Fixes: b78783000d5c ("posix-cpu-timers: Migrate to use new tick dependency mask model") Signed-off-by: Ben Segall Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/xm26o737bq8o.fsf@google.com --- include/linux/tick.h | 8 ++++++++ kernel/fork.c | 2 ++ 2 files changed, 10 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 443726085f6c..832381b812c2 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -233,12 +233,19 @@ static inline void tick_dep_set_task(struct task_struct *tsk, if (tick_nohz_full_enabled()) tick_nohz_dep_set_task(tsk, bit); } + static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { if (tick_nohz_full_enabled()) tick_nohz_dep_clear_task(tsk, bit); } + +static inline void tick_dep_init_task(struct task_struct *tsk) +{ + atomic_set(&tsk->tick_dep_mask, 0); +} + static inline void tick_dep_set_signal(struct signal_struct *signal, enum tick_dep_bits bit) { @@ -272,6 +279,7 @@ static inline void tick_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { } +static inline void tick_dep_init_task(struct task_struct *tsk) { } static inline void tick_dep_set_signal(struct signal_struct *signal, enum tick_dep_bits bit) { } static inline void tick_dep_clear_signal(struct signal_struct *signal, diff --git a/kernel/fork.c b/kernel/fork.c index b65871600507..1fb06d8952bc 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -91,6 +91,7 @@ #include #include #include +#include #include #include @@ -1829,6 +1830,7 @@ static __latent_entropy struct task_struct *copy_process( acct_clear_integrals(p); posix_cpu_timers_init(p); + tick_dep_init_task(p); p->io_context = NULL; audit_set_context(p, NULL); -- 2.46.0