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 C23631EBFF4; Thu, 7 Nov 2024 10:42:46 +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=1730976166; cv=none; b=FOrS2z8DESv+D3bN5TjjLyhisWskdt7x11mk5GSZxYQDVzt43CHNGkEPZReHYHAstQ9VXxmBI+zLOTOtGBVseTNua7AAEpq8T2681YfngzUOf7fvZnV/76zx6lhinxUiiNSKTNuJlOEMhmtPhhahsqfJIkJu4F6hz7l/Y0RPzvI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730976166; c=relaxed/simple; bh=zRpLMPauPAGsguakIW/QvonIxsET1BLwl9GokVEGwV0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UscnuOP0SY8di2oBSuxUov4J13BwQwhVtqu+oBiyspO2l1tQpSk0fChaOvMccTsMcJeR9T01RH3iE7VvjQ4PY2hmNGw3GryNvFe2F2dXn0+9EogX0U4dz38ojuD9qUyH/QZzjo43l7wbdsofC2frF4NhOfzU/p48RhxJStVHtdY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M8OZ3wlc; 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="M8OZ3wlc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00357C4CED5; Thu, 7 Nov 2024 10:42:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730976166; bh=zRpLMPauPAGsguakIW/QvonIxsET1BLwl9GokVEGwV0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M8OZ3wlcajF1rIxpljzudGvrLEbmx5u37+maFP1H89DCtImzheudXJ9KP8hwt0en4 BTuWP8KiNnbSWlylUFeQjMN1vkwX1JCQAkCmSjy3SS4OS4N3VpRYZpDvOOPEsH9+DV N0nW4yjp0oGu1o4YEBuZwGmHLSwC+62y2zBLsMt0H5WTTf86WUK+SJFJQEjN5Z2ySz 4XqQM5yWzkN+68L6sxJVJLChcYTplT3PW6KKO0OjyGLLPNfBoyqxR3+pPfgHEKqJRA WOolivOhB2caeqtonBa0wZhEieWhRemKVnA44Yihy2mQFS7CmE3LB7/uWfj0pwxZtI XkFzE6GwCqCFA== Date: Thu, 7 Nov 2024 11:42:43 +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 v6.6-stable tree Message-ID: References: <20241106020901.164614-1-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: <20241106020901.164614-1-sashal@kernel.org> Le Tue, Nov 05, 2024 at 09:09:00PM -0500, Sasha Levin a écrit : > The patch below does not apply to the v6.6-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 eb2b3ebf29a859e788fe1cee9ca67d8e7ee580e9 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 Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/xm26o737bq8o.fsf@google.com Signed-off-by: Frederic Weisbecker --- 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 32ffbc1c96ba..525937981971 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -99,6 +99,7 @@ #include #include #include +#include #include #include @@ -2417,6 +2418,7 @@ __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