linux-kernel - Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a range

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: <20230828201015.GE1621761@google.com>
Date:   Mon, 28 Aug 2023 20:10:15 +0000
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Lorenzo Stoakes <lstoakes@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-mm@...ck.org, Shuah Khan <shuah@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kirill A Shutemov <kirill@...temov.name>,
        "Liam R. Howlett" <liam.howlett@...cle.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Kalesh Singh <kaleshsingh@...gle.com>,
        Lokesh Gidra <lokeshgidra@...gle.com>
Subject: Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a
 range

On Mon, Aug 28, 2023 at 08:38:17PM +0100, Lorenzo Stoakes wrote:
> On Mon, Aug 28, 2023 at 06:59:12PM +0000, Joel Fernandes wrote:
> > On Sun, Aug 27, 2023 at 11:15:20AM +0100, Lorenzo Stoakes wrote:
> > > On Sun, Aug 27, 2023 at 10:57:59AM +0100, Lorenzo Stoakes wrote:
> > > [snip]
> > >
> > > > > +/*
> > > > > + * Verify that an mremap within a range does not cause corruption
> > > > > + * of unrelated part of range.
> > > > > + *
> > > > > + * Consider the following range which is 2MB aligned and is
> > > > > + * a part of a larger 10MB range which is not shown. Each
> > > > > + * character is 256KB below making the source and destination
> > >
> > > Just noticed, I think you misspeak here, as this test doens't seem to
> > > offset by 256 KiB? That is the strategy for mremap_move_1mb_from_start()
> > > rather than this test so perhaps comment needs to be moved around?
> > >
> > >  * 2MB each. The lower case letters are moved (s to d) and the
> > >  * upper case letters are not moved. The below test verifies
> > >  * that the upper case S letters are not corrupted by the
> > >  * adjacent mremap.
> > >  *
> > >  * |DDDDddddSSSSssss|
> > >  */
> > >  static void mremap_move_within_range(char pattern_seed)
> >
> > Here we are moving 1MB within a 4MB zone of a large mapping. Each character
> > 's' or 'd' is 256KB. The 256KB there is just for illustration and not really
> > significant as such. The 'ssss' is moved to 'dddd' 1MB each. Here we make
> 
> Ahhh I see. I find that a little confusing here, perhaps clearer to say 'each
> block of letters is 1 MiB in size' or something?

Sure, I'll do that.
 
> Cheers!

Cheers. And thanks for the reviews!

 - Joel