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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 3106BC4167B for ; Tue, 27 Dec 2022 20:53:11 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NhRgn5D8rz3fSR for ; Wed, 28 Dec 2022 07:53:09 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=Z1NAhlKl; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4601:e00::1; helo=ams.source.kernel.org; envelope-from=sashal@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=Z1NAhlKl; dkim-atps=neutral Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4NhRJd2036z3cdW for ; Wed, 28 Dec 2022 07:36:33 +1100 (AEDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D9F78B81023; Tue, 27 Dec 2022 20:36:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88EDDC433EF; Tue, 27 Dec 2022 20:36:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672173389; bh=vHtnvMLnNeW0LVpGtBo8msaqdCgegaLg4vDC/O3ZjDM=; h=From:To:Cc:Subject:Date:From; b=Z1NAhlKloh3W8NPhsI/eKxML4zQ+RLD2rLpTv1P53U1Sw98U7QzhRoNNNKiCkJbUN /13Pt8cKZ8Ku39RmKbY+JWA1c5BSFsg0eVJyLtbitv/8LRSnu44pvku4pe7dGXpZQb v8SrHUu67stE1GbAEIGhv2PJWME90nQ1cTnR2ZVK1xGPOPzzF77CsqSEpmKREVLQxq 1OaqAwq1NYXYAgo8Z30RjoVoNNTfRLJqtbgbBMkgdnF+A9ktcPFlmGwjS+2jMULsNL drxNzgMfYvioNGxmTj4Kkzcwq4fJC+HiARH2C58lRRZ3RYRRV7X9J+DIBSUfIE2al3 J9QLRmCP7b2dA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 1/3] powerpc/rtas: avoid scheduling in rtas_os_term() Date: Tue, 27 Dec 2022 15:36:23 -0500 Message-Id: <20221227203626.1214890-1-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nathan Lynch , Sasha Levin , Andrew Donnellan , Nicholas Piggin , sourabhjain@linux.ibm.com, ldufour@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Nathan Lynch [ Upstream commit 6c606e57eecc37d6b36d732b1ff7e55b7dc32dd4 ] It's unsafe to use rtas_busy_delay() to handle a busy status from the ibm,os-term RTAS function in rtas_os_term(): Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b BUG: sleeping function called from invalid context at arch/powerpc/kernel/rtas.c:618 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0 preempt_count: 2, expected: 0 CPU: 7 PID: 1 Comm: swapper/0 Tainted: G D 6.0.0-rc5-02182-gf8553a572277-dirty #9 Call Trace: [c000000007b8f000] [c000000001337110] dump_stack_lvl+0xb4/0x110 (unreliable) [c000000007b8f040] [c0000000002440e4] __might_resched+0x394/0x3c0 [c000000007b8f0e0] [c00000000004f680] rtas_busy_delay+0x120/0x1b0 [c000000007b8f100] [c000000000052d04] rtas_os_term+0xb8/0xf4 [c000000007b8f180] [c0000000001150fc] pseries_panic+0x50/0x68 [c000000007b8f1f0] [c000000000036354] ppc_panic_platform_handler+0x34/0x50 [c000000007b8f210] [c0000000002303c4] notifier_call_chain+0xd4/0x1c0 [c000000007b8f2b0] [c0000000002306cc] atomic_notifier_call_chain+0xac/0x1c0 [c000000007b8f2f0] [c0000000001d62b8] panic+0x228/0x4d0 [c000000007b8f390] [c0000000001e573c] do_exit+0x140c/0x1420 [c000000007b8f480] [c0000000001e586c] make_task_dead+0xdc/0x200 Use rtas_busy_delay_time() instead, which signals without side effects whether to attempt the ibm,os-term RTAS call again. Signed-off-by: Nathan Lynch Reviewed-by: Nicholas Piggin Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221118150751.469393-5-nathanl@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/rtas.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 641f3e4c3380..9a77778bd24a 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -733,10 +733,15 @@ void rtas_os_term(char *str) snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str); + /* + * Keep calling as long as RTAS returns a "try again" status, + * but don't use rtas_busy_delay(), which potentially + * schedules. + */ do { status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL, __pa(rtas_os_term_buf)); - } while (rtas_busy_delay(status)); + } while (rtas_busy_delay_time(status)); if (status != 0) printk(KERN_EMERG "ibm,os-term call failed %d\n", status); -- 2.35.1