Messages in this thread | | | Date | Wed, 8 Dec 2021 15:01:24 +0000 | From | Matthew Wilcox <> | Subject | Re: [PATCH v3 1/2] mm: protect free_pgtables with mmap_lock write lock in exit_mmap |
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On Tue, Dec 07, 2021 at 03:08:19PM -0800, Suren Baghdasaryan wrote: > > > /** > > > * @close: Called when the VMA is being removed from the MM. > > > * Context: Caller holds mmap_lock. > > BTW, is the caller always required to hold mmap_lock for write or it > *might* hold it?
__do_munmap() might hold it for read, thanks to:
if (downgrade) mmap_write_downgrade(mm);
Should probably say:
* Context: User context. May sleep. Caller holds mmap_lock.
I don't think we should burden the implementor of the vm_ops with the knowledge that the VM chooses to not hold the mmap_lock under certain circumstances when it doesn't matter whether it's holding the mmap_lock or not.
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