Messages in this thread | ![/](/images/icornerl.gif) | | From | Suren Baghdasaryan <> | Date | Wed, 18 Jan 2023 10:09:29 -0800 | Subject | Re: [PATCH 17/41] mm/mmap: move VMA locking before anon_vma_lock_write call |
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On Wed, Jan 18, 2023 at 1:23 AM Michal Hocko <mhocko@suse.com> wrote: > > On Tue 17-01-23 18:01:01, Suren Baghdasaryan wrote: > > On Tue, Jan 17, 2023 at 7:16 AM Michal Hocko <mhocko@suse.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. > > Because ....
because vma_adjust_trans_huge() modifies the VMA and such modifications should be done under VMA write-lock protection.
> > Withtout that additional reasonaning it is not really clear why that is > needed and seems arbitrary.
Would the above be a good reasoning?
> > -- > Michal Hocko > SUSE Labs
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