From 4b49a9660d2638681ba98d5a5932fd91eef1a8ec Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 7 May 2020 18:35:46 -0700 Subject: [PATCH] mm/page_alloc: fix watchdog soft lockups during set_zone_contiguous() commit e84fe99b68ce353c37ceeecc95dce9696c976556 upstream. Without CONFIG_PREEMPT, it can happen that we get soft lockups detected, e.g., while booting up. watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.6.0-next-20200331+ #4 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014 RIP: __pageblock_pfn_to_page+0x134/0x1c0 Call Trace: set_zone_contiguous+0x56/0x70 page_alloc_init_late+0x166/0x176 kernel_init_freeable+0xfa/0x255 kernel_init+0xa/0x106 ret_from_fork+0x35/0x40 The issue becomes visible when having a lot of memory (e.g., 4TB) assigned to a single NUMA node - a system that can easily be created using QEMU. Inside VMs on a hypervisor with quite some memory overcommit, this is fairly easy to trigger. Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Pavel Tatashin Reviewed-by: Pankaj Gupta Reviewed-by: Baoquan He Reviewed-by: Shile Zhang Acked-by: Michal Hocko Cc: Kirill Tkhai Cc: Shile Zhang Cc: Pavel Tatashin Cc: Daniel Jordan Cc: Michal Hocko Cc: Alexander Duyck Cc: Baoquan He Cc: Oscar Salvador Cc: Link: http://lkml.kernel.org/r/20200416073417.5003-1-david@redhat.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d387ca74cb5a..4e7e8ded1fc0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1555,6 +1555,7 @@ void set_zone_contiguous(struct zone *zone) if (!__pageblock_pfn_to_page(block_start_pfn, block_end_pfn, zone)) return; + cond_resched(); } /* We confirm that there is no hole */