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Howlett" , Lorenzo Stoakes , Michael Bommarito , Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RESEND] userfaultfd: snapshot VMA state across UFFDIO_COPY retry Message-ID: References: <20260519052516.3315196-1-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0B8F1C0006 X-Stat-Signature: ey5mo7gf7mh87tkuknjbtnnuxwo6pzuu X-HE-Tag: 1779280851-305503 X-HE-Meta: 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 QR3MWr/K vrBUMH1M/aBHQCMlrNamjQJFnwOh+lRGgsrXVSHC6wainlNMCs5j206kfeHa2bWy+xJ4ztB+m+7KEXWlKFa5tdtHcEyMpDeIybgDuqZM1s6aipH001K9A1pooNOvkmC/HJGAXEGTACvb25gH5WJt/6ixgAXh/W0/loLEMvU30etb69WkJMn3p8j32J8Sv3GziejlPuRMAJsqtEMAcmrxoVVELew3zKgLDS4/mgDXnQ6kP8ORMrSZx0FUc1V8ZXOOy3v+8+OkHF3fEVX9GfkjvUVABOIyqy8qedkcxn6I8d4y3aET10Ah3ocIcV0whu86PB8inaDX7ELZMOjUNv+a8/p8dmuikIEs2UfWOdEG2l6lDUBeTdqaEBjF4rwYXUiTXFneXlt3H0aREbwc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi David, On Tue, May 19, 2026 at 06:36:23AM +0100, David CARLIER wrote: > On Tue, 19 May 2026 at 06:25, Mike Rapoport wrote: > > > @@ -69,6 +71,24 @@ static const struct vm_uffd_ops *vma_uffd_ops(struct vm_area_struct *vma) > > return vma->vm_ops ? vma->vm_ops->uffd_ops : NULL; > > } > > > > +static const struct vm_uffd_ops *vma_uffd_copy_ops(struct vm_area_struct *vma) > > > My only 2 cent, I would name it vma_uffd_effective_copy_ops() instead or > a comment to highlight it is about "UFFDIO_COPY into a MAP_PRIVATE file-backed" Too long for my taste :) And comment is useful anyway as it explains why we override the ops at all. > > +{ > > + const struct vm_uffd_ops *ops = vma_uffd_ops(vma); > > + > > + if (!ops) > > + return NULL; > > + > > + /* > > + * UFFDIO_COPY fills MAP_PRIVATE file-backed mappings as anonymous > > + * memory. This is an effective ops override, so retry validation must > > + * compare the override result, not just vma->vm_ops->uffd_ops. > > + */ > > + if (!(vma->vm_flags & VM_SHARED)) > > + return &anon_uffd_ops; > > + > > + return ops; > > +} -- Sincerely yours, Mike.