linux-kernel - Re: [PATCH v3 2/5] kselftest: vm: Fix mdwe's mmap

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Message-ID: <ZOtLEPW+AaiYF6c2@arm.com>
Date:   Sun, 27 Aug 2023 16:09:36 +0300
From:   Catalin Marinas <catalin.marinas@....com>
To:     Florent Revest <revest@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, anshuman.khandual@....com,
        joey.gouly@....com, mhocko@...e.com, keescook@...omium.org,
        david@...hat.com, peterx@...hat.com, izbyshev@...ras.ru,
        broonie@...nel.org, szabolcs.nagy@....com, kpsingh@...nel.org,
        gthelen@...gle.com, toiwoton@...il.com
Subject: Re: [PATCH v3 2/5] kselftest: vm: Fix mdwe's mmap_FIXED test case

On Tue, Jul 04, 2023 at 05:36:26PM +0200, Florent Revest wrote:
> I checked with the original author, the mmap_FIXED test case wasn't
> properly tested and fails. Currently, it maps two consecutive (non
> overlapping) pages and expects the second mapping to be denied by MDWE
> but these two pages have nothing to do with each other so MDWE is
> actually out of the picture here.
> 
> What the test actually intended to do was to remap a virtual address
> using MAP_FIXED. However, this operation unmaps the existing mapping and
> creates a new one so the va is backed by a new page and MDWE is again
> out of the picture, all remappings should succeed.
> 
> This patch keeps the test case to make it clear that this situation is
> expected to work.
> 
> Signed-off-by: Florent Revest <revest@...omium.org>
> Reviewed-by: David Hildenbrand <david@...hat.com>
> Fixes: 4cf1fe34fd18 ("kselftest: vm: add tests for memory-deny-write-execute")

Reviewed-by: Catalin Marinas <catalin.marinas@....com>