linux-kernel - Re: [PATCH v1 1/3] mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY

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] [day] [month] [year] [list]

Message-ID: <qvqwwn25rswa.fsf@devbig1114.prn1.facebook.com>
Date:   Fri, 21 Apr 2023 11:28:49 -0700
From:   Stefan Roesch <shr@...kernel.io>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-s390@...r.kernel.org, linux-kselftest@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Rik van Riel <riel@...riel.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH v1 1/3] mm/ksm: unmerge and clear VM_MERGEABLE when
 setting PR_SET_MEMORY_MERGE=0


David Hildenbrand <david@...hat.com> writes:

>>> I understand we want to keep the name "symmetric" with
>>> ksm_enable_merge_any, but it also unmerges the ksm pages. Do we want to
>>> reflect that in the function name?
>> ksm_disable_merge_any_umerge() is suboptimal.
>> As ksm_disable_merge_any() now reverts what ksm_enable_merge_any() ended
>> up doing, I think it's just fine.
>> (it would be a different story if we'd be using "set" / "clear"
>> terminology instead of "enable" / "disable").
>> We can describe that in the comment.
>>
>>>
>>> Can we add a comment for the function?
>> Can do for symmetry with ksm_enable_merge_any().
>>
>
> +/**
> + * ksm_disable_merge_any - Disable merging on all compatible VMA's of the mm,
> + *                        previously enabled via ksm_enable_merge_any().
> + *
> + * Disabling merging implies unmerging any merged pages, like setting
> + * MADV_UNMERGEABLE would. If unmerging fails, the whole operation fails and
> + * merging on all compatible VMA's remains enabled.
> + *
> + * @mm: Pointer to mm
> + *
> + * Returns 0 on success, otherwise error code
> + */


LGTM

Acked-by: Stefan Roesch <shr@...kernel.io>