linux-kernel - Re: [PATCH v2] mm/page_alloc: fix watchdog soft lockups during set_zone

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Date:   Mon, 20 Apr 2020 09:42:03 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.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>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v2] mm/page_alloc: fix watchdog soft lockups during
 set_zone_contiguous()

On 20.04.20 09:34, Michal Hocko wrote:
> On Fri 17-04-20 15:12:47, Andrew Morton wrote:
>> On Thu, 16 Apr 2020 09:34:17 +0200 David Hildenbrand <david@...hat.com> wrote:
>>
>>> Without CONFIG_PREEMPT, it can happen that we get soft lockups detected,
>>> e.g., while booting up.
>>>
>>> ...
>>>
>>> --- a/mm/page_alloc.c
>>> +++ b/mm/page_alloc.c
>>> @@ -1607,6 +1607,7 @@ 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 */
>>
>> I added cc:stable to this one.  Please let me know if that wasn't a
>> good idea.
> 
> Really large memory setups tend to run on distribution kernels so
> backporting to old kernels doesn't really harm.
> 

Yeah, shouldn't hurt.

-- 
Thanks,

David / dhildenb