Messages in this thread | | | From | Suren Baghdasaryan <> | Date | Thu, 26 Jan 2023 08:18:31 -0800 | Subject | Re: [PATCH v3 6/7] mm: introduce mod_vm_flags_nolock and use it in untrack_pfn |
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On Thu, Jan 26, 2023 at 7:47 AM Mel Gorman <mgorman@techsingularity.net> wrote: > > On Wed, Jan 25, 2023 at 03:35:53PM -0800, Suren Baghdasaryan wrote: > > In cases when VMA flags are modified after VMA was isolated and mmap_lock > > was downgraded, flags modifications would result in an assertion because > > mmap write lock is not held. > > Add note that it's also used during exit when the locking of the VMAs > becomes irrelevant (mm users is 0, should be no VMA modifications taking > place other than zap).
Ack.
> > The typical naming pattern when a caller either knows it holds the necessary > lock or knows it does not matter is __mod_vm_flags()
Ok. It sounds less explicit but plenty of examples, so I'm fine with such rename. Will apply in the next version.
> > > Introduce mod_vm_flags_nolock to be used in such situation, when VMA is > > not part of VMA tree and locking it is not required. > > Instead of such situations, describe in as "used when the caller takes > responsibility for the required locking".
Ack.
> > > Pass a hint to untrack_pfn to conditionally use mod_vm_flags_nolock for > > flags modification and to avoid assertion. > > > > Signed-off-by: Suren Baghdasaryan <surenb@google.com> > > Patch itself looks ok. It strays close to being "conditional locking" > though which might attract some complaints.
The description seems to accurately describe what's done here but I'm open to better suggestions. Thanks!
> > -- > Mel Gorman > SUSE Labs
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