From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id E19256B025E for ; Mon, 18 Sep 2017 08:14:27 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id v109so285781wrc.5 for ; Mon, 18 Sep 2017 05:14:27 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 184sor1826337wmk.75.2017.09.18.05.14.26 for (Google Transport Security); Mon, 18 Sep 2017 05:14:26 -0700 (PDT) From: Michal Hocko 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> In-Reply-To: <20170918121410.24466-1-mhocko@kernel.org> References: <20170918121410.24466-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Dan Williams , LKML , linux-mm@kvack.org, Michal Hocko , Johannes Thumshirn 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 -- 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/ . Don't email: email@kvack.org