linux-kernel - Re: [Patch v4 0/4] mm/mremap: cleanup move_page

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: <20200710011410.GC51939@L-31X9LVDL-1304.local>
Date:   Fri, 10 Jul 2020 09:14:10 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Wei Yang <richard.weiyang@...ux.alibaba.com>,
        akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
        vbabka@...e.cz, yang.shi@...ux.alibaba.com, thomas_os@...pmail.org,
        anshuman.khandual@....com, sean.j.christopherson@...el.com,
        peterx@...hat.com, aneesh.kumar@...ux.ibm.com, willy@...radead.org,
        thellstrom@...are.com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Patch v4 0/4] mm/mremap: cleanup move_page_tables() a little

On Thu, Jul 09, 2020 at 10:38:58PM +0300, Dmitry Osipenko wrote:
>08.07.2020 12:50, Wei Yang пишет:
>> move_page_tables() tries to move page table by PMD or PTE.
>> 
>> The root reason is if it tries to move PMD, both old and new range should be
>> PMD aligned. But current code calculate old range and new range separately.
>> This leads to some redundant check and calculation.
>> 
>> This cleanup tries to consolidate the range check in one place to reduce some
>> extra range handling.
>> 
>> v4:
>>   * remove a redundant parentheses pointed by Kirill
>> 
>> v3:
>>   * merge patch 1 with 2 as suggested by Kirill
>
>>   * add patch 4 to simplify the logic to calculate next and extent
>
>Hello, Wei!
>
>Unfortunately you re-introduced the offending change that was fixed in
>v2 and today's next-20200709 on ARM32 is broken once again:
>
>BUG: Bad rss-counter state mm:db85ec46 type:MM_ANONPAGES val:190
>

Ah, my bad, I forget the error we met last time. It is the different format of
pmd_addr_end.

Sorry for that.

@ Kirill

If you agree, I would leave the extent/next calculation as it is in patch 3.

>Please don't do it ;)
>
>> v2:
>>   * remove 3rd patch which doesn't work on ARM platform. Thanks report and
>>     test from Dmitry Osipenko
>> 
>> Wei Yang (4):
>>   mm/mremap: it is sure to have enough space when extent meets
>>     requirement
>>   mm/mremap: calculate extent in one place
>>   mm/mremap: start addresses are properly aligned
>>   mm/mremap: use pmd_addr_end to simplify the calculate of extent
>> 
>>  include/linux/huge_mm.h |  2 +-
>>  mm/huge_memory.c        |  8 +-------
>>  mm/mremap.c             | 27 ++++++++++-----------------
>>  3 files changed, 12 insertions(+), 25 deletions(-)
>> 

-- 
Wei Yang
Help you, Help me