From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) (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 318DEA3D for ; Tue, 23 Aug 2022 06:27:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661236046; x=1692772046; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=bSeAnQzDpJyFPIeSY9JqILoUkwywcUOSbLiQOQt+oh8=; b=bxAeBGhZOx9tbnzc30kGYpzVOivgve1b13Ciy5agYUZqOVCHmKowDPBW SpbHQfaN0lJDbTRAITLgZF6riLnqf907GnGi+/m/bRDRUAWKqyfTNf+cC hfsGfWEEUmgDrByQIyX5q+rdduYlIUEvqR1amGoeekDXmCh2P3HJU2xXf 0/toO7xnpb1LmaX2GxeGI0feFvYOEVvp1sjXLZwLBat+aJtIpevhDvivj 761vLjXSFm4vV4aZA7ctpHeq724sGKOX9lYmvjd3fHjQ4aT2KQV5bsvnp wCtj8nnNJRjNK6EgYfF3TmU4e4Nd0JfJcJ5wGEdCSoAIlO7n8BjN2zAAc A==; X-IronPort-AV: E=McAfee;i="6500,9779,10447"; a="273989594" X-IronPort-AV: E=Sophos;i="5.93,256,1654585200"; d="scan'208";a="273989594" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Aug 2022 23:27:25 -0700 X-IronPort-AV: E=Sophos;i="5.93,256,1654585200"; d="scan'208";a="642324907" Received: from xujinlon-mobl.ccr.corp.intel.com (HELO [10.254.211.102]) ([10.254.211.102]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Aug 2022 23:27:22 -0700 Message-ID: Date: Tue, 23 Aug 2022 14:27:21 +0800 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Cc: baolu.lu@linux.intel.com, Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Lennert Buytenhek , Bart Van Assche , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d: Fix lockdep splat due to klist iteration in atomic context Content-Language: en-US To: iommu@lists.linux.dev References: <20220819015949.4795-1-baolu.lu@linux.intel.com> From: Baolu Lu In-Reply-To: <20220819015949.4795-1-baolu.lu@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2022/8/19 09:59, Lu Baolu wrote: > With CONFIG_INTEL_IOMMU_DEBUGFS enabled, below lockdep splat are seen > when an I/O fault occurs on a machine with an Intel IOMMU in it. > > DMAR: DRHD: handling fault status reg 3 > DMAR: [DMA Write NO_PASID] Request device [00:1a.0] fault addr 0x0 > [fault reason 0x05] PTE Write access is not set > DMAR: Dump dmar0 table entries for IOVA 0x0 > DMAR: root entry: 0x0000000127f42001 > DMAR: context entry: hi 0x0000000000001502, low 0x000000012d8ab001 > ================================ > WARNING: inconsistent lock state > 5.20.0-0.rc0.20220812git7ebfc85e2cd7.10.fc38.x86_64 #1 Not tainted > -------------------------------- > inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. > rngd/1006 [HC1[1]:SC0[0]:HE0:SE1] takes: > ff177021416f2d78 (&k->k_lock){?.+.}-{2:2}, at: klist_next+0x1b/0x160 > {HARDIRQ-ON-W} state was registered at: > lock_acquire+0xce/0x2d0 > _raw_spin_lock+0x33/0x80 > klist_add_tail+0x46/0x80 > bus_add_device+0xee/0x150 > device_add+0x39d/0x9a0 > add_memory_block+0x108/0x1d0 > memory_dev_init+0xe1/0x117 > driver_init+0x43/0x4d > kernel_init_freeable+0x1c2/0x2cc > kernel_init+0x16/0x140 > ret_from_fork+0x1f/0x30 > irq event stamp: 7812 > hardirqs last enabled at (7811): [] asm_sysvec_apic_timer_interrupt+0x16/0x20 > hardirqs last disabled at (7812): [] irqentry_enter+0x54/0x60 > softirqs last enabled at (7794): [] __irq_exit_rcu+0xf9/0x170 > softirqs last disabled at (7787): [] __irq_exit_rcu+0xf9/0x170 > > The klist iterator functions using spin_*lock_irq*() but the klist > insertion functions using spin_*lock(), combined with the Intel DMAR > IOMMU driver iterating over klists from atomic (hardirq) context, where > pci_get_domain_bus_and_slot() calls into bus_find_device() which iterates > over klists. > > As currently there's no plan to fix the klist to make it safe to use in > atomic context, this fixes the lockdep splat by avoid calling > pci_get_domain_bus_and_slot() in the hardirq context. > > Fixes: 8ac0b64b9735 ("iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk()") > Reported-by: Lennert Buytenhek > Link:https://lore.kernel.org/linux-iommu/Yvo2dfpEh%2FWC+Wrr@wantstofly.org/ > Link:https://lore.kernel.org/linux-iommu/YvyBdPwrTuHHbn5X@wantstofly.org/ > Signed-off-by: Lu Baolu This patch has been queued: https://lore.kernel.org/linux-iommu/20220823061557.1631056-1-baolu.lu@linux.intel.com/ Best regards, baolu