Messages in this thread | | | Date | Wed, 17 Mar 2021 17:18:57 -0400 | From | Peter Xu <> | Subject | Re: [PATCH v2 1/2] mm: Allow non-VM_DONTEXPAND and VM_PFNMAP mappings with MREMAP_DONTUNMAP |
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On Wed, Mar 17, 2021 at 04:44:25PM -0400, Brian Geffon wrote: > Hi Peter,
Hi, Brian,
> Thank you as always for taking a look. This change relies on the > existing check in vma_to_resize on line 686: > https://elixir.bootlin.com/linux/v5.12-rc3/source/mm/mremap.c#L686 > which returns -EFAULT when the vma is VM_DONTEXPAND or VM_PFNMAP.
Do you mean line 676?
https://elixir.bootlin.com/linux/v5.12-rc3/source/mm/mremap.c#L676
I'm not sure whether it'll work for MREMAP_DONTUNMAP, since IIUC MREMAP_DONTUNMAP only works for the remap case with no size change, however in that case in vma_to_resize() we'll bail out even earlier than line 676 when checking against the size:
https://elixir.bootlin.com/linux/v5.12-rc3/source/mm/mremap.c#L667
So IIUC we'll still need the change as Hugh suggested previously.
Thanks,
-- Peter Xu
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