linux-kernel - Re: [PATCH v3 1/1] selftests/mm/uffd: Refactor non-composite global vars into struct

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: <CALkFLLK19Uqr2veWCn79cbLLgde5f+otf9Qx0xSPGdhdnekGrw@mail.gmail.com>
Date: Mon, 26 May 2025 00:49:12 +0530
From: Ujwal Kundur <ujwal.kundur@...il.com>
To: Brendan Jackman <jackmanb@...gle.com>
Cc: akpm@...ux-foundation.org, peterx@...hat.com, shuah@...nel.org, 
	linux-mm@...ck.org, linux-kselftest@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/1] selftests/mm/uffd: Refactor non-composite global
 vars into struct

> Sounds like that's your issue - for the kernel, tab is supposed to be
> as wide as 8 spaces, not 4.

That fixed it, thanks! I've gone through the diff and made sure there
are no longer any inconsistent indents.

> I'm afraid I'm too ignorant of this code to be able to suggest something
> good here. But, can we just remove the comment and plumb the gopts
> through to uffd_poll_thread()->uffd_handle_page_fault()->__copy_page()?
>
> This is not pretty but it lets us remove the global vars which is
> clearly a step in the right direction.

Perhaps Andrew can weigh in? If I understood this correctly, we're
trying to assert that retrying a successful UFFDIO_COPY operation
always results in EEXIST. This is being done in a somewhat racy
fashion where a flag (test_uffdio_copy_eexist) is set every 10 seconds
using alarm(2). IMO this is a flaky test, we should either:
- remove this variable and associated logic entirely (preferred)
- use a probability function to set this a % of the time instead of
every 10 seconds
- use an async library that can replace the implementation without the
use of global vars