linux-kernel - Re: [PATCH RFC 05/13] mm/rmap: remove do_page_add_anon

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 for Android: free password hash cracker in your pocket

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

Message-ID: <CAHk-=wh+NxEVxeKc_o1xyVsJAQNqpN1zyCHN96gPEK+DzXaeLw@mail.gmail.com>
Date:   Thu, 24 Feb 2022 09:29:56 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     David Hildenbrand <david@...hat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>,
        David Rientjes <rientjes@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        John Hubbard <jhubbard@...dia.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Yang Shi <shy828301@...il.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Nadav Amit <namit@...are.com>, Rik van Riel <riel@...riel.com>,
        Roman Gushchin <guro@...com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Donald Dutile <ddutile@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Oleg Nesterov <oleg@...hat.com>, Jan Kara <jack@...e.cz>,
        Liang Zhang <zhangliang5@...wei.com>,
        Pedro Gomes <pedrodemargomes@...il.com>,
        Oded Gabbay <oded.gabbay@...il.com>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH RFC 05/13] mm/rmap: remove do_page_add_anon_rmap()

On Thu, Feb 24, 2022 at 4:29 AM David Hildenbrand <david@...hat.com> wrote:
>
> ... and instead convert page_add_anon_rmap() to accept flags.

Can you fix the comment above the RMAP_xyz definitions? That one still says

  /* bitflags for do_page_add_anon_rmap() */

that tnow no longer exists.

Also, while this kind of code isn't unusual, I think it's still confusing:

> +               page_add_anon_rmap(page, vma, addr, 0);

because when reading that, at least I go "what does 0 mean? Is it a
page offset, or what?"

It might be a good idea to simply add a

  #define RMAP_PAGE 0x00

or something like that, just to have the callers all make it obvious
that we're talking about that RMAP_xyz bits - even if some of them may
be default.

(Then using an enum of a special type is something we do if we want to
add extra clarity or sparse testing, I don't think there are enough
users for that to make sense)

               Linus