Messages in this thread | | | Date | Wed, 10 Aug 2022 17:38:59 +0800 | From | Chao Peng <> | Subject | Re: [PATCH v7 01/14] mm: Add F_SEAL_AUTO_ALLOCATE seal to memfd |
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On Fri, Aug 05, 2022 at 07:55:38PM +0200, Paolo Bonzini wrote: > On 7/21/22 11:44, David Hildenbrand wrote: > > > > Also, I*think* you can place pages via userfaultfd into shmem. Not > > sure if that would count "auto alloc", but it would certainly bypass > > fallocate(). > > Yeah, userfaultfd_register would probably have to forbid this for > F_SEAL_AUTO_ALLOCATE vmas. Maybe the memfile_node can be reused for this, > adding a new MEMFILE_F_NO_AUTO_ALLOCATE flags? Then userfault_register > would do something like memfile_node_get_flags(vma->vm_file) and check the > result.
Then we need change userfault_register uAPI for a new property flag. Userspace should still the decision-maker for this flag.
> > This means moving this patch later, after "mm: Introduce memfile_notifier".
Yes, it makes sense now.
Chao > > Thanks, > > Paolo
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