linux-kernel - [PATCH 4.9 18/90] mm/page_alloc: fix watchdog soft lockups during set_zone

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Date:   Mon, 18 May 2020 19:35:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Baoquan He <bhe@...hat.com>,
        Shile Zhang <shile.zhang@...ux.alibaba.com>,
        Michal Hocko <mhocko@...e.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Oscar Salvador <osalvador@...e.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.9 18/90] mm/page_alloc: fix watchdog soft lockups during set_zone_contiguous()

From: David Hildenbrand <david@...hat.com>

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 <david@...hat.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@...een.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>
Reviewed-by: Baoquan He <bhe@...hat.com>
Reviewed-by: Shile Zhang <shile.zhang@...ux.alibaba.com>
Acked-by: Michal Hocko <mhocko@...e.com>
Cc: Kirill Tkhai <ktkhai@...tuozzo.com>
Cc: Shile Zhang <shile.zhang@...ux.alibaba.com>
Cc: Pavel Tatashin <pasha.tatashin@...een.com>
Cc: Daniel Jordan <daniel.m.jordan@...cle.com>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Alexander Duyck <alexander.duyck@...il.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: <stable@...r.kernel.org>
Link: http://lkml.kernel.org/r/20200416073417.5003-1-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 mm/page_alloc.c |    1 +
 1 file changed, 1 insertion(+)

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1408,6 +1408,7 @@ void set_zone_contiguous(struct zone *zo
 		if (!__pageblock_pfn_to_page(block_start_pfn,
 					     block_end_pfn, zone))
 			return;
+		cond_resched();
 	}
 
 	/* We confirm that there is no hole */