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 53DF61DF72F; Thu, 7 Nov 2024 10:32:29 +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=1730975549; cv=none; b=F4/dNY0LZ/MCubLFA52jZMQUO1PJ6FUA8scJk0qYd4A+qArGr/wGE6mofHE/d1DMucgnvNNqRdbLLVXU3wnad7W/MZQdwT0UAm2Shew1P+Y4shotFHQv+0JGGTOXkNVC3AKsbRBuuU+/GAJO04/gcTWeqiJ/jREjM1KA2/AqGHE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730975549; c=relaxed/simple; bh=zftwGZWn+NcFfV7ZloooFrWn7zlJGxlcpjkWe9gYlLw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c+apbQwBjOVFd3GYhB6fiBrs0sMt4skqsZYg5iszYYlTI7ABeg2aM3HyN+MLaJquITwA3xvbRVYbRyh46km1aDiOt62zJTmNULnEyGIvQcnOTKfmcRaSamlNa68EPHZuCDWXlj7ZjJbUsnZAg5u+88qUgECvLMogKkhnwVPtRA0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OI23klle; 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="OI23klle" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79463C4CECC; Thu, 7 Nov 2024 10:32:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730975548; bh=zftwGZWn+NcFfV7ZloooFrWn7zlJGxlcpjkWe9gYlLw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OI23klleBHMR0yzZMj7BsFVm4O+KNdGs/7UUvwVXWHjpXv/n5jQLG1C67sir353t7 QAaUwp4EBT0Bp5lCxEBaMkHyW5ey7t2ygkVp4p2gf+89jF5cfr4Tml8Ye3oWIop1xC 42aXwmNCGZUrr+69BqAdHxKPlTQNBmS8g/urcJiuY2NUjuQeZ4PHtqAZKwiB9Ls+U/ geFO7qhxeR9FYwJXt+oZ//RsmCQ0n3N3yhuFhV0ogLa+Uws1sab3Uwc3GxPt2KI3HY AORK05G2cJipRQkw1pvuqEJIosZvTR8d7EJRPwGTMqG6iGQJdik87oVGqASmg0pY/E EnKrRvAvyRiQQ== Date: Thu, 7 Nov 2024 11:32:26 +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 v5.10-stable tree Message-ID: References: <20241106021231.182968-1-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: <20241106021231.182968-1-sashal@kernel.org> Le Tue, Nov 05, 2024 at 09:12:31PM -0500, Sasha Levin a écrit : > The patch below does not apply to the v5.10-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 . Please try this one: >From 9f41884fa9493382e59a0d42b2084d37b36bec06 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 a90a8f7759a2..fe38aaacebf0 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -247,12 +247,19 @@ 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) { @@ -286,6 +293,7 @@ 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 8b8a5a172b15..f54d32bcdb21 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -96,6 +96,7 @@ #include #include #include +#include #include #include @@ -2053,6 +2054,7 @@ 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