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 857E41DE4EA; Thu, 7 Nov 2024 10:27:13 +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=1730975233; cv=none; b=L+tubU9hgzSYZ4NcqgH2L26VUUPuFSUuiDpVISh5JLHDcxa8fyt5O9KIoud5eI6rBQjB+dNRudtnmxvELu81aFTkdxcfCB4e/5rST9sbnbt4wJm4mdCTH5S6RT5BP1goF60RcgXNTPgKjzHpzWd6gwbxeyzGcsz7+j6Dzau8Xm8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730975233; c=relaxed/simple; bh=w7LlA+d3P8tWpqL1R1qmf9z0LDa4pqyuLrV0Uk8F5P8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=opUz9OTBtg3zrSYx7viVMR6EI+E2FCaFA7/7Kj61lg0G+ftk2zFvf+SF/qm8mFscG9axpoI26cK5dh9p4PvlJWhLY+kSrUpskW11tXgQZXyUwqliJ0Ts7ULpaxYGk4UaOpKMQ/YCNdrlMQDftxHzVX+RSapAZIClwpNfly7rJOQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eP/941cF; 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="eP/941cF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB8EBC4CED2; Thu, 7 Nov 2024 10:27:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730975233; bh=w7LlA+d3P8tWpqL1R1qmf9z0LDa4pqyuLrV0Uk8F5P8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eP/941cF+syt8TdVfS5qQgfgNj+beEkbClcA9CLeVPm0+Qv+9fFrpv7ADx4ne9kya fSxgRGC+pBQcgKdDiKfCoelY3kcc0v0krcY0d0v1k/fIc86iN5JyRG/ZDt+nfyutVu PVkvfEw0EacbzcsignpQdB93vNGMF8MbcAwtDQuibrX0B662P0sDTIwZoSNH3crUb1 Gs331qaoflK88MxqVayxOEegQq+I233Je6dDyHToVdCu82bHCcwkUIn8JzuK59bVyY oeZ8wj0jaf/9XeXCJurRHTSzc2Et5RqV/IuRzkHenjFGgk2tHmYfzJgmwavwYBBIh8 1OFFzDYpagQpw== Date: Thu, 7 Nov 2024 11:27:10 +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 v5.4-stable tree Message-ID: References: <20241106021327.183601-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20241106021327.183601-1-sashal@kernel.org> Le Tue, Nov 05, 2024 at 09:13:26PM -0500, Sasha Levin a écrit : > The patch below does not apply to the v5.4-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 6b742b3fa045260c3b13e7747332e9d34ca7bbe9 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 cf6c92060929..4634af47f8c2 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -244,12 +244,19 @@ 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) { @@ -283,6 +290,7 @@ 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 1728aa77861c..ce795a61874a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -94,6 +94,7 @@ #include #include #include +#include #include #include @@ -1956,6 +1957,7 @@ static __latent_entropy struct task_struct *copy_process( acct_clear_integrals(p); posix_cputimers_init(&p->posix_cputimers); + tick_dep_init_task(p); p->io_context = NULL; audit_set_context(p, NULL); -- 2.46.0