linux-kernel - Re: [PATCH 17/41] mm/mmap: move VMA locking before anon_vma_lock

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Message-ID: <CAJuCfpGoYaF2-z7FCiN4X8gEGD6nAwnQC+=n3tUHuMWZa7zx8Q@mail.gmail.com>
Date:   Tue, 17 Jan 2023 18:01:01 -0800
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     akpm@...ux-foundation.org, michel@...pinasse.org,
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Subject: Re: [PATCH 17/41] mm/mmap: move VMA locking before
 anon_vma_lock_write call

On Tue, Jan 17, 2023 at 7:16 AM Michal Hocko <mhocko@...e.com> wrote:
>
> On Mon 09-01-23 12:53:12, Suren Baghdasaryan wrote:
> > Move VMA flag modification (which now implies VMA locking) before
> > anon_vma_lock_write to match the locking order of page fault handler.
>
> Does this changelog assumes per vma locking in the #PF?

Hmm, you are right. Page fault handlers do not use per-vma locks yet
but the changelog already talks about that. Maybe I should change it
to simply:
```
Move VMA flag modification (which now implies VMA locking) before
vma_adjust_trans_huge() to ensure the modifications are done after VMA
has been locked.
```
Is that better?

>
> --
> Michal Hocko
> SUSE Labs