On Wed, Jan 4, 2023 at 10:52 PM Peter Xu <peterx@xxxxxxxxxx> wrote: > > Before this patch, when there's any pgtable allocation issues happened > during change_protection(), the error will be ignored from the syscall. > For shmem, there will be an error dumped into the host dmesg. Two issues > with that: > > (1) Doing a trace dump when allocation fails is not anything close to > grace.. > > (2) The user should be notified with any kind of such error, so the user > can trap it and decide what to do next, either by retrying, or stop > the process properly, or anything else. > > For userfault users, this will change the API of UFFDIO_WRITEPROTECT when > pgtable allocation failure happened. It should not normally break anyone, > though. If it breaks, then in good ways. > > One man-page update will be on the way to introduce the new -ENOMEM for > UFFDIO_WRITEPROTECT. Not marking stable so we keep the old behavior on the > 5.19-till-now kernels. > > Reported-by: James Houghton <jthoughton@xxxxxxxxxx> > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> Acked-by: James Houghton <jthoughton@xxxxxxxxxx> Thanks Peter! :)
