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  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]
Date:   Fri, 23 Jul 2021 07:10:12 +0800
From:   "Huang, Ying" <>
To:     Christian Borntraeger <>
Cc:     Sean Christopherson <>,
        Yang Shi <>, Zi Yan <>,
        Andrew Morton <>,
        Linux MM <>,
        Linux Kernel Mailing List <>,
        Dan Carpenter <>,
        Mel Gorman <>,
        Gerald Schaefer <>,
        Heiko Carstens <>,
        Hugh Dickins <>,
        Andrea Arcangeli <>,
        "Kirill A . Shutemov" <>,
        Michal Hocko <>,
        Vasily Gorbik <>,
        Paolo Bonzini <>,
        kvm list <>
Subject: Re: [PATCH] mm,do_huge_pmd_numa_page: remove unnecessary TLB
 flushing code

Christian Borntraeger <> writes:

> On 22.07.21 02:26, Huang, Ying wrote:
>> Sean Christopherson <> writes:
>>>> Thanks, I think you are correct. By looking into commit 7066f0f933a1
>>>> ("mm: thp: fix mmu_notifier in migrate_misplaced_transhuge_page()"),
>>>> the tlb flush and mmu notifier invalidate were needed since the old
>>>> numa fault implementation didn't change PTE to migration entry so it
>>>> may cause data corruption due to the writes from GPU secondary MMU.
>>>> The refactor does use the generic migration code which converts PTE to
>>>> migration entry before copying data to the new page.
>>> That's my understanding as well, based on this blurb from commit 7066f0f933a1.
>>>      The standard PAGE_SIZEd migrate_misplaced_page is less accelerated and
>>>      uses the generic migrate_pages which transitions the pte from
>>>      numa/protnone to a migration entry in try_to_unmap_one() and flushes TLBs
>>>      and all mmu notifiers there before copying the page.
>>> That analysis/justification for removing the invalidate_range() call should be
>>> captured in the changelog.  Confirmation from Andrea would be a nice bonus.
>> When we flush CPU TLB for a page that may be shared with device/VM
>> TLB,
>> we will call MMU notifiers for the page to flush the device/VM TLB.
>> Right?  So when we replaced CPU TLB flushing in do_huge_pmd_numa_page()
>> with that in try_to_migrate_one(), we will replace the MMU notifiers
>> calling too.  Do you agree?
> Can someone write an updated commit messages that contains this information?

OK.  I will update the patch description to add MMU notifiers

Best Regards,
Huang, Ying

Powered by blists - more mailing lists