From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from hall.aurel32.net (hall.aurel32.net [195.154.119.183]) (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 4B9B52C3260; Wed, 18 Mar 2026 20:19:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.154.119.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773865148; cv=none; b=G//xW2NRVcl4kWwOJ7Tj7BDsGAdZ4AG1QvKDt0P5CbgFh0IX3YR/6/783Hw9K9dzj6H8QaS1Mg172GGN8n3kCVrrB032h7vBY0R8Ulcgaxq6qxuHijGTYUrb9RzWEjhgUimK+8iAHeqCFCAFeEWJU1qVs5yNS+5o9MShylr071g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773865148; c=relaxed/simple; bh=EO3wSRBu5SqnfI6b5Vu5ucbO5N4qU/ypzS1wIJ1cvwo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NOpMHLiezXLkl6wfZu8LewhoT/aqokNxF9JhgvGczGTavBZJTTGTvzDVhpXHcducRS7k2d7VtHVJ4ul8qladFtuWhgfw5aLPKiDYlqrisR9IvCyDUZnXsL7k1lPohBgQK3m5x1lwjDgUme8oANegvoI49/GRivKzfZTWlQE/RUU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=aurel32.net; spf=pass smtp.mailfrom=aurel32.net; dkim=pass (2048-bit key) header.d=aurel32.net header.i=@aurel32.net header.b=vEHWcxnc; arc=none smtp.client-ip=195.154.119.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=aurel32.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=aurel32.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=aurel32.net header.i=@aurel32.net header.b="vEHWcxnc" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=aurel32.net ; s=202004.hall; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Content-Transfer-Encoding:From:Reply-To: Subject:Content-ID:Content-Description:X-Debbugs-Cc; bh=LdG7Sm2ptAX6UD2HdakCYLcb1OHihIX1Cvex0rU/AzQ=; b=vEHWcxncGlGcDZ2E2SyOFxqoah 2WmJFbz3N8WKv/AokAOdGDTSiTQabVDPNE8RT1b+jLassaXtmMF/TU+zMr0DDbsIa28VikweVyfDy 3puPxOdf93Lo0fTxixjeKGbyMQIxouBO9nwJCjGP07EdShAyA06FV0hSQKU0DdGThsyNKQ38tDNlf k6nCQGcjvfMF0WNNGn9kPZyMUoHiGytt6/QelGiA3/y8dLQ21BYZZPq7KBIO/QduaZ+PihHuxjODT oSYHQbEmn8wgXQD8DMKaEIyu6f0HwDDX82IeSONEOmIS2A+wCp/mqzIE7L0/RTOzltGE9PSqtRlOw l7PvXFQQ==; Received: from authenticated user by hall.aurel32.net with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1w2xLy-00000005fER-1Kds; Wed, 18 Mar 2026 21:18:54 +0100 Date: Wed, 18 Mar 2026 21:18:53 +0100 From: Aurelien Jarno To: Troy Mitchell Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, spacemit@lists.linux.dev Subject: Re: [PATCH v2] riscv: disable local interrupts and stop other CPUs before reboot/shutdown Message-ID: Mail-Followup-To: Troy Mitchell , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, spacemit@lists.linux.dev References: <20260317-v7-0-rc1-rv-dis-int-before-restart-v2-1-0ecc85fbb7ff@linux.dev> Precedence: bulk X-Mailing-List: spacemit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260317-v7-0-rc1-rv-dis-int-before-restart-v2-1-0ecc85fbb7ff@linux.dev> User-Agent: Mutt/2.2.13 (2024-03-09) Hi Troy, On 2026-03-17 16:48, Troy Mitchell wrote: > Currently, the RISC-V implementation of machine_restart(), machine_halt(), > and machine_power_off() invokes the kernel teardown chains (e.g., > do_kernel_restart()) with local interrupts enabled and other CPUs still > running. > > This implementation fails to provide a deterministic execution environment > for registered handlers in the restart or power-off notifier chains. These > chains are intended to be executed in a strict atomic and single-threaded > context. > > Specifically, under CONFIG_PREEMPT_RCU, rcu_read_lock() does not increment > the preempt_count. If local interrupts remain enabled, the environment > is not guaranteed to be atomic. This can lead to a context misidentification > within generic kernel teardown code, causing it to incorrectly enter > non-atomic paths (such as attempting to acquire sleeping locks), which > results in fatal "scheduling while atomic" splats or system hangs. > > Additionally, stopping other CPUs ensures the primary CPU has exclusive > access to the hardware state during the final teardown phase, preventing > unpredictable interference from other active cores. > > Align RISC-V with other major architectures by disabling local interrupts > and stopping other CPUs at the beginning of the shutdown sequences. This > guarantees the architectural expectations of the kernel's restart and > power-off handlers are met. > > Signed-off-by: Troy Mitchell > --- > Changes in v2: > - expand the fix to cover machine_halt() and machine_power_off() for > architectural consistency. > - update commit message > - Link to v1: https://lore.kernel.org/r/20260311-v7-0-rc1-rv-dis-int-before-restart-v1-1-bc46b4351cac@linux.dev > --- > arch/riscv/kernel/reset.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/riscv/kernel/reset.c b/arch/riscv/kernel/reset.c > index 912288572226..8c48466c50e9 100644 > --- a/arch/riscv/kernel/reset.c > +++ b/arch/riscv/kernel/reset.c > @@ -5,6 +5,7 @@ > > #include > #include > +#include > > static void default_power_off(void) > { > @@ -17,18 +18,27 @@ EXPORT_SYMBOL(pm_power_off); > > void machine_restart(char *cmd) > { > + local_irq_disable(); > + smp_send_stop(); > + > do_kernel_restart(cmd); > while (1); > } > > void machine_halt(void) > { > + local_irq_disable(); > + smp_send_stop(); > + > do_kernel_power_off(); > default_power_off(); > } > > void machine_power_off(void) > { > + local_irq_disable(); > + smp_send_stop(); > + > do_kernel_power_off(); > default_power_off(); > } > > --- > base-commit: 31489a8c1e95cfa2039b7ec4abf124d1fdda31a6 > change-id: 20260311-v7-0-rc1-rv-dis-int-before-restart-5b3e52a4b419 > > Best regards, > -- > Troy Mitchell Thanks for this new version. I confirm it works fine. Tested-by: Aurelien Jarno Regards Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://aurel32.net