From patchwork Wed Jan 15 00:45:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 233872 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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=no 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 244C0C33C9E for ; Wed, 15 Jan 2020 00:46:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2CB02467D for ; Wed, 15 Jan 2020 00:46:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579049162; bh=vB+NQWVWTftjiIpUzM72wGOLW9Y+aFl2LmP/C5QrPAY=; h=Date:From:To:Subject:List-ID:From; b=wxxP0Zl00TJAMsug2o7ueeNTrZRgxOrNV0aiuCWDwlw79knL+fyX5/lIAhR/RiAMD eTLUxtazlzAROKx36p+sLBKRwhVuqm4jKbP3aXU++dmxyQXlvRlY9cq29ip+HSdTLm fEvFC+7ucBt9XVUmJuhOyY5DyGIYuvuX06CiBa80= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728913AbgAOAqB (ORCPT ); Tue, 14 Jan 2020 19:46:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:48914 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728795AbgAOAqB (ORCPT ); Tue, 14 Jan 2020 19:46:01 -0500 Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (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 17D46222C3; Wed, 15 Jan 2020 00:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579049160; bh=vB+NQWVWTftjiIpUzM72wGOLW9Y+aFl2LmP/C5QrPAY=; h=Date:From:To:Subject:From; b=sB8R2SXwRIMMrbSutMLEc0g7WbJ/x+V2YkO2ryhS9quMQhMFZarSDWZbzHs9tBcwl dddjPvsQ64n+Oef8a41aLPkIGFf8rzbYz+UTRDBTiAWE49Xm2tgbsCG6kIgEZRJ1AM bNFlEcM7a+nSNAs2kOtWvJnoslgOUNDPSbkANBAk= Date: Tue, 14 Jan 2020 16:45:59 -0800 From: akpm@linux-foundation.org To: ahuang12@lenovo.com, cl@linux.com, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, jroedel@suse.de, lixc17@lenovo.com, mhocko@kernel.org, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, shakeelb@google.com, stable@vger.kernel.org Subject: [merged] mm-memcg-slab-call-flush_memcg_workqueue-only-if-memcg-workqueue-is-valid.patch removed from -mm tree Message-ID: <20200115004559.KYHzqxCuy%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid has been removed from the -mm tree. Its filename was mm-memcg-slab-call-flush_memcg_workqueue-only-if-memcg-workqueue-is-valid.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Adrian Huang Subject: mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid When booting with amd_iommu=off, the following WARNING message appears: AMD-Vi: AMD IOMMU disabled on kernel command-line ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/workqueue.c:2772 flush_workqueue+0x42e/0x450 Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.5.0-rc3-amd-iommu #6 Hardware name: Lenovo ThinkSystem SR655-2S/7D2WRCZ000, BIOS D8E101L-1.00 12/05/2019 RIP: 0010:flush_workqueue+0x42e/0x450 Code: ff 0f 0b e9 7a fd ff ff 4d 89 ef e9 33 fe ff ff 0f 0b e9 7f fd ff ff 0f 0b e9 bc fd ff ff 0f 0b e9 a8 fd ff ff e8 52 2c fe ff <0f> 0b 31 d2 48 c7 c6 e0 88 c5 95 48 c7 c7 d8 ad f0 95 e8 19 f5 04 RSP: 0000:ffffffff96203d80 EFLAGS: 00010246 RAX: ffffffff96203dc8 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffffffff96a63120 RSI: ffffffff95efcba2 RDI: ffffffff96203dc0 RBP: ffffffff96203e08 R08: 0000000000000000 R09: ffffffff962a1828 R10: 00000000f0000080 R11: dead000000000100 R12: ffff8d8a87c0a770 R13: dead000000000100 R14: 0000000000000456 R15: ffffffff96203da0 FS: 0000000000000000(0000) GS:ffff8d8dbd000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff8d91cfbff000 CR3: 000000078920a000 CR4: 00000000000406b0 Call Trace: ? wait_for_completion+0x51/0x180 kmem_cache_destroy+0x69/0x260 iommu_go_to_state+0x40c/0x5ab amd_iommu_prepare+0x16/0x2a irq_remapping_prepare+0x36/0x5f enable_IR_x2apic+0x21/0x172 default_setup_apic_routing+0x12/0x6f apic_intr_mode_init+0x1a1/0x1f1 x86_late_time_init+0x17/0x1c start_kernel+0x480/0x53f secondary_startup_64+0xb6/0xc0 ---[ end trace 30894107c3749449 ]--- x2apic: IRQ remapping doesn't support X2APIC mode x2apic disabled The warning is caused by the calling of 'kmem_cache_destroy()' in free_iommu_resources(). Here is the call path: free_iommu_resources kmem_cache_destroy flush_memcg_workqueue flush_workqueue The root cause is that the IOMMU subsystem runs before the workqueue subsystem, which the variable 'wq_online' is still 'false'. This leads to the statement 'if (WARN_ON(!wq_online))' in flush_workqueue() is 'true'. Since the variable 'memcg_kmem_cache_wq' is not allocated during the time, it is unnecessary to call flush_memcg_workqueue(). This prevents the WARNING message triggered by flush_workqueue(). Link: http://lkml.kernel.org/r/20200103085503.1665-1-ahuang12@lenovo.com Fixes: 92ee383f6daab ("mm: fix race between kmem_cache destroy, create and deactivate") Signed-off-by: Adrian Huang Reported-by: Xiaochun Lee Reviewed-by: Shakeel Butt Cc: Joerg Roedel Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Michal Hocko Cc: Johannes Weiner Cc: Signed-off-by: Andrew Morton --- mm/slab_common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/slab_common.c~mm-memcg-slab-call-flush_memcg_workqueue-only-if-memcg-workqueue-is-valid +++ a/mm/slab_common.c @@ -903,7 +903,8 @@ static void flush_memcg_workqueue(struct * deactivates the memcg kmem_caches through workqueue. Make sure all * previous workitems on workqueue are processed. */ - flush_workqueue(memcg_kmem_cache_wq); + if (likely(memcg_kmem_cache_wq)) + flush_workqueue(memcg_kmem_cache_wq); /* * If we're racing with children kmem_cache deactivation, it might