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 D9671183CA6; Mon, 12 Aug 2024 16:09:52 +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=1723478992; cv=none; b=O7vOtxoQsRWgqkpIsY+ZviRoxxRrVNtrOByKtiI9wF/fogzZltynh/oQeCIz9waiCiBNWjx+iE6WHX3rRwmL6nOMOm3u/W5zrUx9OPxYfsUzcjFTV++Q5jlN2HxW058istJVwZc8wDHF/m9lrTC6RU+5ij8c9uDIE+a893yTya0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723478992; c=relaxed/simple; bh=Nkk6IzKyDnt7qpCRLYKtfsDNXq/euEUXLvUVXpusFZM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GekOA/bwoX54/4Or3ljWL8DwoaKscHaf9wZ4GyNlM0CCSZYFcEE9TtTaHo7YOsIhBKj0ffaYZ9thQ5RS81QC0iGJl/8yqZY4YgOe5z5TQSDcZKA4gu3YAtl+42Hvo9g9Y1K7LqfCRq6xCJ4AYKsotKzCjGjVlRrAdk1Prv24Les= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RuFqfuB0; 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="RuFqfuB0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FC63C32782; Mon, 12 Aug 2024 16:09:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723478992; bh=Nkk6IzKyDnt7qpCRLYKtfsDNXq/euEUXLvUVXpusFZM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RuFqfuB05dJXETfN1AtIEnXAKWIWUUYee8XvqjlhN7YqSTm6yezUZTMIOV70jX/hP 60UbsL1KnnqMUqCW2ZXETFGCG8vJ/BtFGTjpvLDqiSZ392ClBP7EpIwM6FHEX0X4cv T01gFihJMrkr2l6NecC3LAhpiPiqukQSCOSRqdhU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Wang <00107082@163.com>, Thomas Gleixner , Yu Liao Subject: [PATCH 6.1 100/150] tick/broadcast: Move per CPU pointer access into the atomic section Date: Mon, 12 Aug 2024 18:03:01 +0200 Message-ID: <20240812160129.020325551@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240812160125.139701076@linuxfoundation.org> References: <20240812160125.139701076@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 6881e75237a84093d0986f56223db3724619f26e upstream. The recent fix for making the take over of the broadcast timer more reliable retrieves a per CPU pointer in preemptible context. This went unnoticed as compilers hoist the access into the non-preemptible region where the pointer is actually used. But of course it's valid that the compiler keeps it at the place where the code puts it which rightfully triggers: BUG: using smp_processor_id() in preemptible [00000000] code: caller is hotplug_cpu__broadcast_tick_pull+0x1c/0xc0 Move it to the actual usage site which is in a non-preemptible region. Fixes: f7d43dd206e7 ("tick/broadcast: Make takeover of broadcast hrtimer reliable") Reported-by: David Wang <00107082@163.com> Signed-off-by: Thomas Gleixner Tested-by: Yu Liao Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/87ttg56ers.ffs@tglx Signed-off-by: Greg Kroah-Hartman --- kernel/time/tick-broadcast.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -1137,7 +1137,6 @@ void tick_broadcast_switch_to_oneshot(vo #ifdef CONFIG_HOTPLUG_CPU void hotplug_cpu__broadcast_tick_pull(int deadcpu) { - struct tick_device *td = this_cpu_ptr(&tick_cpu_device); struct clock_event_device *bc; unsigned long flags; @@ -1163,6 +1162,8 @@ void hotplug_cpu__broadcast_tick_pull(in * device to avoid the starvation. */ if (tick_check_broadcast_expired()) { + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); + cpumask_clear_cpu(smp_processor_id(), tick_broadcast_force_mask); tick_program_event(td->evtdev->next_event, 1); }