linux-kernel - Re: [PATCH v1] mm/gup: remove (VM_)BUG

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Message-ID: <f0d925f4-e133-4cd0-8840-096b0858243e@nvidia.com>
Date: Thu, 24 Jul 2025 10:27:30 -0700
From: John Hubbard <jhubbard@...dia.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Vlastimil Babka <vbabka@...e.cz>
Cc: Jason Gunthorpe <jgg@...pe.ca>, David Hildenbrand <david@...hat.com>,
 Michal Hocko <mhocko@...e.com>, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Mike Rapoport
 <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
 Peter Xu <peterx@...hat.com>
Subject: Re: [PATCH v1] mm/gup: remove (VM_)BUG_ONs

On 7/24/25 3:56 AM, Lorenzo Stoakes wrote:
> On Thu, Jul 24, 2025 at 12:54:26PM +0200, Vlastimil Babka wrote:
>> On 6/9/25 11:57, Vlastimil Babka wrote:
>>> On 6/7/25 8:00 PM, John Hubbard wrote:
>>>> On 6/7/25 6:53 AM, Lorenzo Stoakes wrote:
>>>> The worst part is that if you go to reproduce a problem, you don't
>>>> see the next warning in the logs!! This is devastating, especially if
>>>> the site makes it hard to ask for a system reboot. (If you have
>>>> ~20,000 nodes in the cluster, a reboot is not a small affair.)
>>>
>>> Assuming you know how to reproduce the problem... I wonder if it would
>>> help if there was a way (sysctl?) to re-arm all the _ONCE warnings. It
>>> shouldn't be that hard hopefully?
>>
>> Oh hey it already exists, since 2017
>>
>> echo 1 > /sys/kernel/debug/clear_warn_once
> 
> Ohhh! Nice!

WOW, how did I go all this time without knowing about that? It's just
what I always wanted! :)

thanks,
-- 
John Hubbard