linux-kernel - Re: [PATCH] mm: be more verbose for alloc_contig

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 8 Mar 2021 15:13:35 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, joaodias@...gle.com
Subject: Re: [PATCH] mm: be more verbose for alloc_contig_range faliures

On 08.03.21 15:11, Michal Hocko wrote:
> On Mon 08-03-21 14:22:12, David Hildenbrand wrote:
>> On 08.03.21 13:49, Michal Hocko wrote:
> [...]
>>> Earlier in the discussion I have suggested dynamic debugging facility.
>>> Documentation/admin-guide/dynamic-debug-howto.rst. Have you tried to
>>> look into that direction?
>>
>> Did you see the previous mail this is based on:
>>
>> https://lkml.kernel.org/r/YEEUq8ZRn4WyYWVx@google.com
>>
>> I agree that "nofail" is misleading. Rather something like
>> "dump_on_failure", just a better name :)
> 
> Yeah, I have read through the email thread. I just do not get why we
> cannot make it pr_debug() and add -DDYNAMIC_DEBUG_MODULE for
> page_alloc.c (I haven't checked whether that is possible for built in
> compile units, maybe it is not but from a quick seems it should).
> 
> I really do not like this to be a part of the API. alloc_contig_range is

Which API? It does not affect alloc_contig_range() itself, it's used 
internally only. Sure, we could simply pr_debug() for each and every 
migration failure. As long as it's default-disabled, sure.

I do agree that we should look into properly including this into the 
dynamic debugging ifrastructure.

-- 
Thanks,

David / dhildenb