Messages in this thread |  | | From | David CARLIER <> | | Date | Thu, 2 Apr 2026 06:59:13 +0100 | | Subject | Re: [PATCH v4] mm/userfaultfd: detect VMA replacement after copy retry in mfill_copy_folio_retry() |
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Understood on all points. Will rework patch 1 to a simple ops comparison with -ENOENT, drop vma_snapshot entirely. Will cc MEMORY MAPPING folks.
Holding off until after -rc1, will resend both then.
Cheers.
On Thu, 2 Apr 2026 at 05:02, Mike Rapoport <rppt@kernel.org> wrote: > > On Wed, Apr 01, 2026 at 03:22:03PM -0400, Peter Xu wrote: > > > > The other thing is I just noticed the err code was changed to -EINVAL for > > snapshot changed cases, sorry I didn't follow previously as closely on the > > discussion. I think it should be -EAGAIN. It's because the userapp can't > > resolve -EINVAL failures and app will crash. In a VMA change use case, we > > should return -EAGAIN to imply the app to retry, rather than crashing. > > No. The return value should express that the VMA is invalid. -EINVAL could > work, but looking now at the manual -ENOENT would be even better: > > ENOENT (since Linux 4.11) > The faulting process has changed its virtual memory layout > simultaneously with an outstanding UFFDIO_COPY operation. > > > Thanks, > > -- > > Peter Xu > > -- > Sincerely yours, > Mike.
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