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Howlett" , Nikita Kalyazin , Michal Hocko , David Hildenbrand , Andrea Arcangeli , Oscar Salvador , Axel Rasmussen , Ujwal Kundur Subject: Re: [PATCH v2 3/4] mm/hugetlb: Support vm_uffd_ops API Message-ID: References: <20250627154655.2085903-1-peterx@redhat.com> <20250627154655.2085903-4-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250627154655.2085903-4-peterx@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 02F6CA0004 X-Stat-Signature: 6mb11mf6ryt3taqf5eof8tiqf5zocc8n X-HE-Tag: 1751187157-168823 X-HE-Meta: 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 7v4wj87Z dpsJu461zhGioBUwVzLlQc1iLV0nWToE8e4+zORhq6FrwMy1oZKDRnzY6MSQH/XCIuCOn4nydLz9pGppiXTYHTyqo9lftyJ11qUu5Y2IRZGe9I/riJqV1aeCXXF52hvaLBhcpfPjHlg9GDVrhtZc4BqqPjtSjC5Pw2rd5ExfBC+PP0+le6jA42ThqtYkCh1kfJrqNZGRBotfYZqZAZ1gMtXGdSOMGuPbG3IEvDzlvsF7+5I+eDkcFtZgTxYYgfFyUtX0hytkgWCM2CPADAN5DHY2xUZpGpkxd4pv7q2JsEbrde9vTM/28YEePGZLSXkTdy9RoCIOhXNPLNcxTTItgXYniREFvb+nsYUFldDk5eQ5C0cUyuVxsC+6jEDBmwntbUlZ4btfV/XVCkbaB/H/TKFurHEdQWMrVelWw X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 27, 2025 at 11:46:54AM -0400, Peter Xu wrote: > Add support for the new vm_uffd_ops API for hugetlb. Note that this only > introduces the support, the API is not yet used by core mm. > > Due to legacy reasons, it's still not trivial to move hugetlb completely to > the API (like shmem). But it will still use uffd_features and uffd_ioctls > properly on the API because that's pretty general. > > Cc: Muchun Song > Cc: Oscar Salvador > Signed-off-by: Peter Xu Acked-by: Mike Rapoport (Microsoft) > --- > mm/hugetlb.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 11d5668ff6e7..ccd2be152d36 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -5457,6 +5457,22 @@ static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf) > return 0; > } > > +#ifdef CONFIG_USERFAULTFD > +static const vm_uffd_ops hugetlb_uffd_ops = { > + .uffd_features = __VM_UFFD_FLAGS, > + /* _UFFDIO_ZEROPAGE not supported */ > + .uffd_ioctls = BIT(_UFFDIO_COPY) | > + BIT(_UFFDIO_WRITEPROTECT) | > + BIT(_UFFDIO_CONTINUE) | > + BIT(_UFFDIO_POISON), > + /* > + * Hugetlbfs still has its own hard-coded handler in userfaultfd, > + * due to limitations similar to vm_operations_struct.fault(). > + * TODO: generalize it to use the API functions. > + */ > +}; > +#endif > + > /* > * When a new function is introduced to vm_operations_struct and added > * to hugetlb_vm_ops, please consider adding the function to shm_vm_ops. > @@ -5470,6 +5486,9 @@ const struct vm_operations_struct hugetlb_vm_ops = { > .close = hugetlb_vm_op_close, > .may_split = hugetlb_vm_op_split, > .pagesize = hugetlb_vm_op_pagesize, > +#ifdef CONFIG_USERFAULTFD > + .userfaultfd_ops = &hugetlb_uffd_ops, > +#endif > }; > > static pte_t make_huge_pte(struct vm_area_struct *vma, struct folio *folio, > -- > 2.49.0 > -- Sincerely yours, Mike.