From patchwork Thu Aug 17 16:14:53 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 9906655 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 266166024A for ; Thu, 17 Aug 2017 16:17:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 19BBB28B52 for ; Thu, 17 Aug 2017 16:17:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0E6FB28B6B; Thu, 17 Aug 2017 16:17:44 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7BA8A28B52 for ; Thu, 17 Aug 2017 16:17:43 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1diNRs-0004IR-HV; Thu, 17 Aug 2017 16:15:08 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1diNRq-0004IA-E4 for xen-devel@lists.xen.org; Thu, 17 Aug 2017 16:15:06 +0000 Received: from [85.158.143.35] by server-2.bemta-6.messagelabs.com id F6/31-27137-901C5995; Thu, 17 Aug 2017 16:15:05 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrHLMWRWlGSWpSXmKPExsVysyfVTZfz4NR Ig8v/WS2WfFzM4sDocXT3b6YAxijWzLyk/IoE1oxbu1YyFbyVqrgy8TtLA2OzeBcjF4eQwGZG iSXnW5m6GDmBnNOMEive6IDYbAKaEnc+fwKLiwhIS1z7fJkRxGYWKJX49OUomC0sECvRu3ABm M0ioCrx6uAsdhCbV8BSYvmm42BxCQF5iV1tF1lBbE4BK4lPn9ayQ+yylDi37wzLBEbuBYwMqx g1ilOLylKLdA3N9ZKKMtMzSnITM3N0DQ3M9HJTi4sT01NzEpOK9ZLzczcxAv3LAAQ7GG9vDDj EKMnBpCTK+3vWlEghvqT8lMqMxOKM+KLSnNTiQ4wyHBxKErzv90+NFBIsSk1PrUjLzAEGGkxa goNHSYRX+QBQmre4IDG3ODMdInWK0ZJjw+r1X5g47vRtAJKvJvz/xiTEkpeflyolznsIZJ4AS ENGaR7cOFg0XGKUlRLmZQQ6UIinILUoN7MEVf4VozgHo5IwbyPIFJ7MvBK4ra+ADmICOuhK+y SQg0oSEVJSDYz9Gf4pNou217y001fQ+fDly0Ku+fVq3f0rPXZ5vqx8ad46veZK8RTrqaY5v3o lH5zzyVH/v/pJ+Ym6u39yL1ifXHgh5EXPNIGzCbKHN19cltWWZ3p1qqo6955kzZevKz0UY6cm n1gZvFuVw1X0P8/U/JdKP1Ju8v94IyruvGpxXNnOS9u93rxWYinOSDTUYi4qTgQAvJf2eYECA AA= X-Env-Sender: julien.grall@arm.com X-Msg-Ref: server-11.tower-21.messagelabs.com!1502986504!75264263!1 X-Originating-IP: [217.140.101.70] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 9.4.45; banners=-,-,- X-VirusChecked: Checked Received: (qmail 2860 invoked from network); 17 Aug 2017 16:15:04 -0000 Received: from foss.arm.com (HELO foss.arm.com) (217.140.101.70) by server-11.tower-21.messagelabs.com with SMTP; 17 Aug 2017 16:15:04 -0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 30573164F; Thu, 17 Aug 2017 09:15:04 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.206.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2181B3F577; Thu, 17 Aug 2017 09:15:02 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xen.org Date: Thu, 17 Aug 2017 17:14:53 +0100 Message-Id: <20170817161453.19318-2-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170817161453.19318-1-julien.grall@arm.com> References: <20170817161453.19318-1-julien.grall@arm.com> Cc: jgross@suse.com, boris.ostrovsky@oracle.com, Julien Grall , linux-kernel@vger.kernel.org Subject: [Xen-devel] [PATCH] xen/events: events_fifo: Don't use {get, put}_cpu() in xen_evtchn_fifo_init() X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP When booting Linux as Xen guest with CONFIG_DEBUG_ATOMIC, the following splat appears: [ 0.002323] Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes) [ 0.019717] ASID allocator initialised with 65536 entries [ 0.020019] xen:grant_table: Grant tables using version 1 layout [ 0.020051] Grant table initialized [ 0.020069] BUG: sleeping function called from invalid context at /data/src/linux/mm/page_alloc.c:4046 [ 0.020100] in_atomic(): 1, irqs_disabled(): 0, pid: 1, name: swapper/0 [ 0.020123] no locks held by swapper/0/1. [ 0.020143] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc5 #598 [ 0.020166] Hardware name: FVP Base (DT) [ 0.020182] Call trace: [ 0.020199] [] dump_backtrace+0x0/0x270 [ 0.020222] [] show_stack+0x24/0x30 [ 0.020244] [] dump_stack+0xb8/0xf0 [ 0.020267] [] ___might_sleep+0x1c8/0x1f8 [ 0.020291] [] __might_sleep+0x58/0x90 [ 0.020313] [] __alloc_pages_nodemask+0x1c0/0x12e8 [ 0.020338] [] alloc_page_interleave+0x38/0x88 [ 0.020363] [] alloc_pages_current+0xdc/0xf0 [ 0.020387] [] __get_free_pages+0x28/0x50 [ 0.020411] [] evtchn_fifo_alloc_control_block+0x2c/0xa0 [ 0.020437] [] xen_evtchn_fifo_init+0x38/0xb4 [ 0.020461] [] xen_init_IRQ+0x44/0xc8 [ 0.020484] [] xen_guest_init+0x250/0x300 [ 0.020507] [] do_one_initcall+0x44/0x130 [ 0.020531] [] kernel_init_freeable+0x120/0x288 [ 0.020556] [] kernel_init+0x18/0x110 [ 0.020578] [] ret_from_fork+0x10/0x40 [ 0.020606] xen:events: Using FIFO-based ABI [ 0.020658] Xen: initializing cpu0 [ 0.027727] Hierarchical SRCU implementation. [ 0.036235] EFI services will not be available. [ 0.043810] smp: Bringing up secondary CPUs ... This is because get_cpu() in xen_evtchn_fifo_init() will disable preemption, but __get_free_page() might sleep (GFP_ATOMIC is not set). xen_evtchn_fifo_init() will always be called before SMP is initialized, so {get,put}_cpu() could be replaced by a simple smp_processor_id(). This also avoid to modify evtchn_fifo_alloc_control_block that will be called in other context. Signed-off-by: Julien Grall Reported-by: Andre Przywara Fixes: 1fe565517b57 ("xen/events: use the FIFO-based ABI if available") --- drivers/xen/events/events_fifo.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c index 3c41470c7fc4..76b318e88382 100644 --- a/drivers/xen/events/events_fifo.c +++ b/drivers/xen/events/events_fifo.c @@ -432,12 +432,12 @@ static int xen_evtchn_cpu_dead(unsigned int cpu) int __init xen_evtchn_fifo_init(void) { - int cpu = get_cpu(); + int cpu = smp_processor_id(); int ret; ret = evtchn_fifo_alloc_control_block(cpu); if (ret < 0) - goto out; + return ret; pr_info("Using FIFO-based ABI\n"); @@ -446,7 +446,6 @@ int __init xen_evtchn_fifo_init(void) cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE, "xen/evtchn:prepare", xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead); -out: - put_cpu(); + return ret; }