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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BD24C64E7B for ; Tue, 17 Nov 2020 13:32:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFD9221534 for ; Tue, 17 Nov 2020 13:32:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="dfJikF6i" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731886AbgKQNce (ORCPT ); Tue, 17 Nov 2020 08:32:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:42286 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732309AbgKQNcd (ORCPT ); Tue, 17 Nov 2020 08:32:33 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EF18E2078E; Tue, 17 Nov 2020 13:32:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605619953; bh=8rYnH8nIj5RsHFfoO7A7+jZnzmRVEIBRQGnSz3oEm7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dfJikF6ihqlGLkOZ39mibPpgWPd34Yz2EcC6kzGfUVbUcms4KPla4oZDQEjVpXhsZ bbWjtaeYJS3TxTf3dZ+UEp9JprjOQFYEwl5W3c/WKcR97LXODfwDM+XDujo2zFkvpe qRekWzqjU1WhZ4+WjtlJAXNlJAzPgrwDEzTM3U2k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qian Cai , Oliver OHalloran , Michael Ellerman , Sasha Levin Subject: [PATCH 5.9 029/255] powerpc/eeh_cache: Fix a possible debugfs deadlock Date: Tue, 17 Nov 2020 14:02:49 +0100 Message-Id: <20201117122140.362795722@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201117122138.925150709@linuxfoundation.org> References: <20201117122138.925150709@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Qian Cai [ Upstream commit fd552e0542b4532483289cce48fdbd27b692984b ] Lockdep complains that a possible deadlock below in eeh_addr_cache_show() because it is acquiring a lock with IRQ enabled, but eeh_addr_cache_insert_dev() needs to acquire the same lock with IRQ disabled. Let's just make eeh_addr_cache_show() acquire the lock with IRQ disabled as well. CPU0 CPU1 ---- ---- lock(&pci_io_addr_cache_root.piar_lock); local_irq_disable(); lock(&tp->lock); lock(&pci_io_addr_cache_root.piar_lock); lock(&tp->lock); *** DEADLOCK *** lock_acquire+0x140/0x5f0 _raw_spin_lock_irqsave+0x64/0xb0 eeh_addr_cache_insert_dev+0x48/0x390 eeh_probe_device+0xb8/0x1a0 pnv_pcibios_bus_add_device+0x3c/0x80 pcibios_bus_add_device+0x118/0x290 pci_bus_add_device+0x28/0xe0 pci_bus_add_devices+0x54/0xb0 pcibios_init+0xc4/0x124 do_one_initcall+0xac/0x528 kernel_init_freeable+0x35c/0x3fc kernel_init+0x24/0x148 ret_from_kernel_thread+0x5c/0x80 lock_acquire+0x140/0x5f0 _raw_spin_lock+0x4c/0x70 eeh_addr_cache_show+0x38/0x110 seq_read+0x1a0/0x660 vfs_read+0xc8/0x1f0 ksys_read+0x74/0x130 system_call_exception+0xf8/0x1d0 system_call_common+0xe8/0x218 Fixes: 5ca85ae6318d ("powerpc/eeh_cache: Add a way to dump the EEH address cache") Signed-off-by: Qian Cai Reviewed-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201028152717.8967-1-cai@redhat.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/eeh_cache.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/eeh_cache.c b/arch/powerpc/kernel/eeh_cache.c index 6b50bf15d8c19..bf3270426d82d 100644 --- a/arch/powerpc/kernel/eeh_cache.c +++ b/arch/powerpc/kernel/eeh_cache.c @@ -264,8 +264,9 @@ static int eeh_addr_cache_show(struct seq_file *s, void *v) { struct pci_io_addr_range *piar; struct rb_node *n; + unsigned long flags; - spin_lock(&pci_io_addr_cache_root.piar_lock); + spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags); for (n = rb_first(&pci_io_addr_cache_root.rb_root); n; n = rb_next(n)) { piar = rb_entry(n, struct pci_io_addr_range, rb_node); @@ -273,7 +274,7 @@ static int eeh_addr_cache_show(struct seq_file *s, void *v) (piar->flags & IORESOURCE_IO) ? "i/o" : "mem", &piar->addr_lo, &piar->addr_hi, pci_name(piar->pcidev)); } - spin_unlock(&pci_io_addr_cache_root.piar_lock); + spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags); return 0; } -- 2.27.0