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 209C5213ECB; Tue, 12 Nov 2024 10:24:57 +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=1731407098; cv=none; b=bILzvSup0AiqKxgcp2aArcx3nK45D310OWA8dTIjB7pVlSwiwHaAKnucZz45pbYNQmWgnVG/IUTaFJJGBAa1WVefm6psmcoeYz6fP073VtqAiEAau1xe5PzP7yZBVsbOoQkRPC/LJpmo1Zfu1rtanG5+WFkkhhpx6tqP1X+sRP8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731407098; c=relaxed/simple; bh=NXQAXMNFgdp3hHtFa8iu0cCBFFkLKei9JOjRfoEXnQE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LFNrb5FNg6VOyS8YlS+1U06JpQWDy8RGE4MwIOizx1V1I8vvufNHIht1H0RjaAdBmmy5WYivuO+naydyM+NR8lOWIniVVb4jdemy1PUXL2FCWto71wYeIubPUJuGsVA/eJDTUkx9fEcKNrsAgtSKzdPTm/NNv/0JmbonG2TBXLw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HX3gQa15; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HX3gQa15" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52C38C4CED8; Tue, 12 Nov 2024 10:24:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1731407097; bh=NXQAXMNFgdp3hHtFa8iu0cCBFFkLKei9JOjRfoEXnQE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HX3gQa15ScXV8upv9lLc5me4p9Ec1ui9lmGeCkIhdWl4bzdsQjge384U/5I4svHMa A4iA8IaZ4mFOBa1/6DwMS83d8wU9SkpSXV3NHoPbKB47exkTlkk7MZWygCjjdpLrTR 66nfArFAW8P0x3eDCBXHsH9/qdINiZortaXVYDnI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ben Segall , Thomas Gleixner , Frederic Weisbecker , Sasha Levin Subject: [PATCH 5.15 49/76] posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone Date: Tue, 12 Nov 2024 11:21:14 +0100 Message-ID: <20241112101841.650944154@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241112101839.777512218@linuxfoundation.org> References: <20241112101839.777512218@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Benjamin Segall [ Upstream commit b5413156bad91dc2995a5c4eab1b05e56914638a ] 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 Signed-off-by: Sasha Levin --- 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 9459fef5b8573..9701c571a5cfe 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 fec103ae640ff..23ffcf8a859c5 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); -- 2.43.0