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 7CD4C1EE024; Thu, 7 Nov 2024 10:37:40 +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=1730975860; cv=none; b=aVLLjtAm8gdXFenfw+oD+UxRP0ImqyCGnLVf/uxG82bLtea8LUcbIstN4iqrYI43THsti+RP1XUXHO5VUsciVHZqxuAYvDtsOrggV6s9tvnmkpd2nOzCujuvxRxP/Qdq75PmeDaikeD5nQOGh9AUy+1jxKhM0QHJs40IFLnGmpM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730975860; c=relaxed/simple; bh=IV6NnD8adAnUKMEzmLFpfBCgOY7VG6juo/usQ46euSM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WHzdDXdcfbqx+YyqlMbAYbxsLsoFwUtxbg7TWnE43DSQyHywD3QvbrZzTavZGGTBmVNfOnFAeEzkm9mhaoZhM+jqbQCioaRxF5vbrb7+IK2be5qanXwsX/1gy07ljAVcaNuXS5eGdAJ5CFKKkct/GRre9NWyjw+eRKRC39zYezs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ffWFnKme; 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="ffWFnKme" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E42FBC4CED2; Thu, 7 Nov 2024 10:37:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730975860; bh=IV6NnD8adAnUKMEzmLFpfBCgOY7VG6juo/usQ46euSM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ffWFnKmeJ/Dt99iAM/xE4yEOct4Kt3OpoOAR3j+3P794y/be+bFud4aXqKmvIhCIq vELCBDZX2uPDOyLmgz/nNnufDcKlyGpo6Fu2/DRYq6hPAM203sFn48yARgWWYVvFVA +wV2DTZWRINFLZBvpbGY/Br78c6rfvFYbLUk4cQ6DBoV/TXLjLtcXZ+RkgmN0ha1/t ER8JtCEkWCaIQ27nS8g8D74ihI4Ya2+f6c7kXCbYSOm5KHIn+IqFA5Mq2X9F75D29F Nd28PZKELcLKTbT2XcITnJr+YOw+eHDrz7pgRg+B7WG8dANLCQSA3BABM8KlAfy6D6 b19ce+HlLdEkA== Date: Thu, 7 Nov 2024 11:37:37 +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 v5.15-stable tree Message-ID: References: <20241106021136.182329-1-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: <20241106021136.182329-1-sashal@kernel.org> Le Tue, Nov 05, 2024 at 09:11:36PM -0500, Sasha Levin a écrit : > The patch below does not apply to the v5.15-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 one instead: >From 806ef66e95663c8fce77a7b9ffb8788b11105307 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 9459fef5b857..9701c571a5cf 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -252,12 +252,19 @@ 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 task_struct *tsk, enum tick_dep_bits bit) { @@ -291,6 +298,7 @@ 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 task_struct *tsk, 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 fec103ae640f..23ffcf8a859c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -97,6 +97,7 @@ #include #include #include +#include #include #include @@ -2126,6 +2127,7 @@ 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