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charset="us-ascii" Received-SPF: pass client-ip=2607:f8b0:4864:20::b49; envelope-from=3Row5ZAYKCm0dPLYUNRZZRWP.NZXbPXf-OPgPWYZYRYf.ZcR@flex--seanjc.bounces.google.com; helo=mail-yb1-xb49.google.com X-Spam_score_int: -95 X-Spam_score: -9.6 X-Spam_bar: --------- X-Spam_report: (-9.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_MED=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, USER_IN_DEF_DKIM_WL=-7.5 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Apr 14, 2023, Michal Hocko wrote: > On Fri 14-04-23 00:11:49, Ackerley Tng wrote: > > 3. A more generic fbind(): it seems like this new functionality is > > really only needed for restrictedmem files, hence a separate, > > specific syscall was proposed to avoid complexities with handling > > conflicting policies that may be specified via other syscalls like > > mbind() > > I do not think it is a good idea to make the syscall restrict mem > specific. +1. IMO, any uAPI that isn't directly related to the fundamental properties of restricted memory, i.e. isn't truly unique to restrictedmem, should be added as generic fd-based uAPI. > History shows that users are much more creative when it comes > to usecases than us. I do understand that the nature of restricted > memory is that it is not mapable but memory policies without a mapping > are a reasonable concept in genereal. After all this just tells where > the memory should be allocated from. Do we need to implement that for > any other fs? No, you can safely return EINVAL for anything but > memfd_restricted fd for now but you shouldn't limit usecases upfront. I would even go a step further and say that we should seriously reconsider the design/implemenation of memfd_restricted() if a generic fbind() needs explicit handling from the restricted memory code. One of the goals with memfd_restricted() is to rely on the underlying backing store to handle all of the "normal" behaviors.