linux-kernel - Re: [PATCH 1/2] mm: Make 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]

Message-ID: <21c17c7429896cc259255340c6e3d61b@suse.de>
Date:   Thu, 18 Feb 2021 17:53:26 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        David Hildenbrand <david@...hat.com>,
        Muchun Song <songmuchun@...edance.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: Make alloc_contig_range handle free hugetlb pages

On 2021-02-18 14:59, Michal Hocko wrote:
> As I've said. Page allocator can cope with NULL nodemask just fine.
> I have checked the code and now remember the tricky part. It is
> alloc_gigantic_page which cannot work with NULL nodemask because it
> relies on for_each_node_mask and that, unlike zonelist iterator, cannot
> cope with NULL node mask. This is the case only for !GFP_THISNODE.

Ok, thanks for the clarification.

> OK, I see the problem now. And your above solution is not really
> optimal either. Your put_page would add the page to the pool and so it
> could be used by somebody. One

Yeah, that is right.

> way around it would be either directly
> manipulating reference count which is fugly or you can make it a
> temporal page (alloc_migrate_huge_page) or maybe even better not 
> special
> case this here but rather allow migrating free hugetlb pages in the
> migrate_page path.

I will have a look into it to see how what would look.

Thanks for the feedback

-- 
Oscar Salvador
SUSE L3