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 D2F451AC8BB; Thu, 15 Aug 2024 14:01:39 +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=1723730499; cv=none; b=KSPzwa72cXtkStlcO0lcQ1hgjsJb8J8pCLCPejlB4JUMlcUHjO68zoCGcxqYK6aFMJE9EF4cAcSTL+imp/GeBjEA+VFqXT5H3iqcso1rXSoAtm5kjF5xvajP4XQDKA8UW4BG71Y5cIMypafzA9B2/VRl/k9uHZ/D4Ib9Vn/BIZw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723730499; c=relaxed/simple; bh=w9qwJHpyPN8BkQ0mEEIyryeg8c950MrD1jr6CzFxWTs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lL7uTaDRvkZCWEDFeYfSt+YouR/1+NAsEu5Er2hSPu50t6afrWQHbG21tF3Ng2v996gHAsc6atU7FQrLC1uNjoB14/ixklO5Ly2a4g2Ze5w1O8iM8hflgomN/3hblOKvATwamIA7Hr2qg7x7kqbN/iuYyddBc5EA4YQqhmJJlQM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KnzyomCZ; 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="KnzyomCZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58BF2C32786; Thu, 15 Aug 2024 14:01:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723730499; bh=w9qwJHpyPN8BkQ0mEEIyryeg8c950MrD1jr6CzFxWTs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KnzyomCZ+FSnd5XZmAtZ14+3COaHdeugnTZ6hsZm9OC2k/f2WG9Vft/3gGHvXpBsd fzDsWPhElh9wL8S508pvxp18sIOdNeJX0UVDodTOuE7jQWpEv6o5b1CLkKiGBwhsKe r9hGEAfGB0IagFdG8AoSnSjm7RE4b/Q1eF9nP8OY= 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 5.15 426/484] tick/broadcast: Move per CPU pointer access into the atomic section Date: Thu, 15 Aug 2024 15:24:44 +0200 Message-ID: <20240815131957.911354089@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131941.255804951@linuxfoundation.org> References: <20240815131941.255804951@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: 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); }