From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id EA71F8D0001 for ; Fri, 12 Nov 2010 13:56:34 -0500 (EST) Subject: (mem hotplug, pcpu_alloc) BUG: sleeping function called from invalid context at kernel/mutex.c:94 From: Alok Kataria Reply-To: akataria@vmware.com Content-Type: text/plain Date: Fri, 12 Nov 2010 10:56:18 -0800 Message-Id: <1289588178.7486.15.camel@ank32.eng.vmware.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: linux-mm , LKML Cc: Tejun Heo , Andrew Morton , Petr Vandrovec List-ID: Hi, We have seen following might_sleep warning while hot adding memory... [ 142.339267] BUG: sleeping function called from invalid context at kernel/mutex.c:94 [ 142.339276] in_atomic(): 0, irqs_disabled(): 1, pid: 4, name: migration/0 [ 142.339283] Pid: 4, comm: migration/0 Not tainted 2.6.35.6-45.fc14.x86_64 #1 [ 142.339288] Call Trace: [ 142.339305] [] __might_sleep+0xeb/0xf0 [ 142.339316] [] mutex_lock+0x24/0x50 [ 142.339326] [] pcpu_alloc+0x6d/0x7ee [ 142.339336] [] ? load_balance+0xbe/0x60e [ 142.339343] [] ? rt_se_boosted+0x21/0x2f [ 142.339349] [] ? dequeue_rt_stack+0x18b/0x1ed [ 142.339356] [] __alloc_percpu+0x10/0x12 [ 142.339362] [] setup_zone_pageset+0x38/0xbe [ 142.339373] [] ? build_zonelists_node.clone.58+0x79/0x8c [ 142.339384] [] __build_all_zonelists+0x419/0x46c [ 142.339395] [] ? cpu_stopper_thread+0xb2/0x198 [ 142.339401] [] stop_machine_cpu_stop+0x8e/0xc5 [ 142.339407] [] ? stop_machine_cpu_stop+0x0/0xc5 [ 142.339414] [] cpu_stopper_thread+0x108/0x198 [ 142.339420] [] ? schedule+0x5b2/0x5cc [ 142.339426] [] ? cpu_stopper_thread+0x0/0x198 [ 142.339434] [] kthread+0x7f/0x87 [ 142.339443] [] kernel_thread_helper+0x4/0x10 [ 142.339449] [] ? kthread+0x0/0x87 [ 142.339455] [] ? kernel_thread_helper+0x0/0x10 [ 142.340099] Built 5 zonelists in Node order, mobility grouping on. Total pages: 289456 [ 142.340108] Policy zone: Normal This warning was seen on the FC14 kernel, though looking at the current git, the problem seems to exist on mainline too. The problem is that pcpu_alloc expects that it is called from non-atomic context as a result it grabs the pcpu_alloc_mutex. In the memory-hotplug case though, we do end up calling pcpu_alloc from atomic context, while all cpus are stopped. void build_all_zonelists(void *data) { set_zonelist_order(); if (system_state == SYSTEM_BOOTING) { __build_all_zonelists(NULL); mminit_verify_zonelist(); cpuset_init_current_mems_allowed(); } else { /* we have to stop all cpus to guarantee there is no user of zonelist */ stop_machine(__build_all_zonelists, data, NULL); <========= /* cpuset refresh routine should be here */ } __build_all_zonelists eventually calls pcpu_alloc. I didn't dive through the history, so am not sure when was this regression introduced, but could have regressed with the new pcpu memory allocator. -- Alok -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org