From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755895AbdIRMOa (ORCPT ); Mon, 18 Sep 2017 08:14:30 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:36271 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752502AbdIRMO1 (ORCPT ); Mon, 18 Sep 2017 08:14:27 -0400 X-Google-Smtp-Source: AOwi7QBY/6WPXWnXBP+qIdZAY9jqqUj5qa1m688oG96kVdBcbhbvZ72Ebz8wXZGfnORX5k+w6pFcrg== From: Michal Hocko To: Andrew Morton Cc: Dan Williams , LKML , , Michal Hocko , Johannes Thumshirn Subject: [PATCH 3/3] memremap: add scheduling point to devm_memremap_pages Date: Mon, 18 Sep 2017 14:14:10 +0200 Message-Id: <20170918121410.24466-4-mhocko@kernel.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170918121410.24466-1-mhocko@kernel.org> References: <20170918121410.24466-1-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko devm_memremap_pages is initializing struct pages in for_each_device_pfn and that can take quite some time. We have even seen a soft lockup trigerring on a non preemptive kernel [ 125.583233] NMI watchdog: BUG: soft lockup - CPU#61 stuck for 22s! [kworker/u641:11:1808] [...] [ 125.583467] RIP: 0010:[] [] devm_memremap_pages+0x327/0x430 [...] [ 125.583488] Call Trace: [ 125.583496] [] pmem_attach_disk+0x2fd/0x3f0 [nd_pmem] [ 125.583528] [] nvdimm_bus_probe+0x64/0x110 [libnvdimm] [ 125.583536] [] driver_probe_device+0x1f7/0x420 [ 125.583540] [] bus_for_each_drv+0x52/0x80 [ 125.583543] [] __device_attach+0xb0/0x130 [ 125.583546] [] bus_probe_device+0x87/0xa0 [ 125.583548] [] device_add+0x3fc/0x5f0 [ 125.583553] [] nd_async_device_register+0xe/0x40 [libnvdimm] [ 125.583556] [] async_run_entry_fn+0x43/0x150 [ 125.583561] [] process_one_work+0x14e/0x410 [ 125.583563] [] worker_thread+0x116/0x490 [ 125.583565] [] kthread+0xc7/0xe0 [ 125.583569] [] ret_from_fork+0x3f/0x70 fix this by adding cond_resched every 1024 pages. Reported-by: Johannes Thumshirn Signed-off-by: Michal Hocko --- kernel/memremap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/memremap.c b/kernel/memremap.c index 6bcbfbf1a8fd..403ab9cdb949 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -350,7 +350,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, pgprot_t pgprot = PAGE_KERNEL; struct dev_pagemap *pgmap; struct page_map *page_map; - int error, nid, is_ram; + int error, nid, is_ram, i = 0; align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) @@ -448,6 +448,8 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, list_del(&page->lru); page->pgmap = pgmap; percpu_ref_get(ref); + if (!(++i % 1024)) + cond_resched(); } devres_add(dev, page_map); return __va(res->start); -- 2.14.1