From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 623CEC79FA0 for ; Tue, 8 Sep 2026 07:55:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=VRXRVay6xLDZY+t9lcPrWvUb1XaHgPwRKdlm/Zpxbzo=; b=qhjrap3FYMPdJi2mIat1EKw6Pv CQ2tzSY53lnu8ws76VuL81WJDcQXC1hgk7hGos+W/k38dyhtUqD69Yif7lJBhWEcKLAHPi98+vMmf 387qmutCodHwb8XoicaiVW59A5R7ZL7oqYAPjrDIekCwcG2CBuyVvuWbW2JEU88WVfi7OycWm1lWn QbzS3rkY6cqGU9ggIGdknakQph6MB78NY6MGRioYdW+BQXLigmX9UcmNzYTpNoJmxsdam8Y4I53dU eTFc86zuPmQQiDHEzu3gudI10i8sSvTQFT1sf5DP16c+FkwPbno0Jd2r9zBqNKjePqctXXZz4NwGA KTrRG/vg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3qfX-00000008JzC-3ctJ; Tue, 08 Sep 2026 07:55:03 +0000 Received: from galois.linutronix.de ([193.142.43.55]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3qfV-00000008Jxh-1iY6 for linux-arm-kernel@lists.infradead.org; Tue, 08 Sep 2026 07:55:02 +0000 Date: Tue, 8 Sep 2026 09:54:55 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1788854097; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VRXRVay6xLDZY+t9lcPrWvUb1XaHgPwRKdlm/Zpxbzo=; b=MTDe8PJKy74mVVCxKtrjvDjyETtY0k1cqzIZziqdC7jbt6wfLpZ8zhjCzYpJhCHwy6wuYK 6hrzjO7dmx3Al/CY1uADqQXo7Tu2Ofg067RiGi9q/GcFvIKwr5Xd3bi7+kJQlem0obsdiU TaV/TbrSrslnYKCYD30aBmCsK9zFgBjkog6SvsQNGEFYh63ifrd4eXgA79Dosp7qiUtkr7 B5dgUPYhGyJwVGhgOq5lZ1lBg3PA5fbC9JcqYLwTW9ivMi/9zJkVIvCPQEtWJhCEvjsf1C iDjhnl7Bg85zPff4JVLn4D2s9LJazauY0Qw/zlTNNegPjA+s0deMXaDvLCFVjg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1788854097; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VRXRVay6xLDZY+t9lcPrWvUb1XaHgPwRKdlm/Zpxbzo=; b=Ywr7ePjS5TdqcKhAM5Xa5HO7Cqd6lr5qXZOzO2PgPrTykoYnGCTddGdthPyYuioQvx9hLm xyfCWP7dsxUfByCg== From: Sebastian Andrzej Siewior To: Russell King Cc: Steven Rostedt , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-perf-users@vger.kernel.org, loongarch@lists.linux.dev, Mark Rutland , Ian Rogers , Peter Zijlstra , "Luis Claudio R. Goncalves" , Catalin Marinas , James Clark , Huacai Chen , Adrian Hunter , Oleg Nesterov , Alexander Shishkin , Ingo Molnar , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Waiman Long , WANG Xuerui , Will Deacon , Clark Williams Subject: Re: [PATCH v2] ARM, ARM64, LONGARCH: Delay HW BP notification to task_work() Message-ID: <20260908075455.OffmMhrB@linutronix.de> References: <20260814085118.OPEA_Ssn@linutronix.de> <20260903160710.vVf4gEL2@linutronix.de> <20260903133146.07095885@gandalf.local.home> <20260904155404.ESPFg3zi@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260908_005501_594646_7FC1C10F X-CRM114-Status: GOOD ( 33.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2026-09-07 15:46:09 [+0100], Russell King wrote: > On Fri, Sep 04, 2026 at 05:54:04PM +0200, Sebastian Andrzej Siewior wrote: > > On 2026-09-03 13:31:46 [-0400], Steven Rostedt wrote: > > > On Thu, 3 Sep 2026 17:47:24 +0100 > > > Russell King wrote: > > > > > > > What do you expect to happen with this? Which arch maintainer should > > > > apply this patch that affects three different independently maintained > > > > architectures? > > > > Well, if you as the ARM person are fine with ARM part, an ACK would be > > appreciated. If you have something to object, it would be nice to let me > > know so I can adjust accordingly. > > First, I only just looked at the email - you may have noticed I'm not > very active with the kernel anymore, as I'm a full-time carer at the > moment. > > Second, I'm not fine with the patch as-is, because it's not clear how > it could be merged in its current form. It would be inappropriate to > give an Ack, because an Ack means I'm fine with it. I'm not. > > Third, I haven't actually reviewed the patch itself (see first point). > > Looking deeper now, I see nothing in the linked report, nor in your > write-up that identifies what is responsible for the context being > inappropriate to deliver the SIGTRAP. See the first point - I'm not The linked report shows a backtrace by "BUG: sleeping function" originating from el0_breakpt() -> perf_bp_event() following by sending a signal force_sig_fault() followed by rt_spin_lock() and __might_resched(). It also contains a reproducer. The first sentence has the part | The hardware event is | delivered with disabled interrupts and perf intrastrucure expects | disabled interrupts while the overflow callback is invoked. This is what happens, followed by | The callback then sends a SIGTRAP signal for which it acquires | sighand_struct::siglock, a spinlock_t which becomes a sleeping lock and | must not be acquired in atomic context. This is not really specific to PREEMPT_RT as we enforce to not allow raw_spinlock_t -> spinlock_t on !PREEMPT_RT via lockdep, too. > able to read lots of code to work that out, and presumably you've > already done that ground work to come up with a fix. This is *vital* > information when someone looks back at why this change was made as > it helps to understand how the problem occurs. This is, after all, > the whole point of commit messages - to help people look back and > understand why a change was made. The "what the changes are" part > is already covered by the patch showing what the changes were. It's > the stuff that *isn't* in the patch that needs to be in the commit > message. > > So... don't describe the code changes in a commit message. I think both parts (describing the issue and the change) are part of the commit message. > So no, an Ack is not appropriate. Sebastian