Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934140AbdCJL1o (ORCPT ); Fri, 10 Mar 2017 06:27:44 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:37142 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933933AbdCJJSu (ORCPT ); Fri, 10 Mar 2017 04:18:50 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Williams , Ben Hutchings , Michal Hocko , Toshi Kani , Vlastimil Babka , Logan Gunthorpe , Masayoshi Mizuma , Andrew Morton , Linus Torvalds Subject: [PATCH 4.9 042/153] mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done} Date: Fri, 10 Mar 2017 10:07:55 +0100 Message-Id: <20170310083949.634702525@linuxfoundation.org> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170310083947.108106897@linuxfoundation.org> References: <20170310083947.108106897@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2370 Lines: 63 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit b5d24fda9c3dce51fcb4eee459550a458eaaf1e2 upstream. The mem_hotplug_{begin,done} lock coordinates with {get,put}_online_mems() to hold off "readers" of the current state of memory from new hotplug actions. mem_hotplug_begin() expects exclusive access, via the device_hotplug lock, to set mem_hotplug.active_writer. Calling mem_hotplug_begin() without locking device_hotplug can lead to corrupting mem_hotplug.refcount and missed wakeups / soft lockups. [dan.j.williams@intel.com: v2] Link: http://lkml.kernel.org/r/148728203365.38457.17804568297887708345.stgit@dwillia2-desk3.amr.corp.intel.com Link: http://lkml.kernel.org/r/148693885680.16345.17802627926777862337.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: f931ab479dd2 ("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}") Signed-off-by: Dan Williams Reported-by: Ben Hutchings Cc: Michal Hocko Cc: Toshi Kani Cc: Vlastimil Babka Cc: Logan Gunthorpe Cc: Masayoshi Mizuma Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/memremap.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -246,9 +246,13 @@ static void devm_memremap_pages_release( /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(resource_size(res), SECTION_SIZE); + + lock_device_hotplug(); mem_hotplug_begin(); arch_remove_memory(align_start, align_size); mem_hotplug_done(); + unlock_device_hotplug(); + untrack_pfn(NULL, PHYS_PFN(align_start), align_size); pgmap_radix_release(res); dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc, @@ -360,9 +364,11 @@ void *devm_memremap_pages(struct device if (error) goto err_pfn_remap; + lock_device_hotplug(); mem_hotplug_begin(); error = arch_add_memory(nid, align_start, align_size, true); mem_hotplug_done(); + unlock_device_hotplug(); if (error) goto err_add_memory;