On Thu, Mar 05, 2009 at 01:27:07PM -0800, Dave Hansen wrote: > > Imagine, unsupported file is opened between userspace checks > > for /proc/*/checkpointable and /proc/*/fdinfo/*/checkpointable > > and whatever, you stil have to do all the checks inside checkpoint(2). > > Alexey, we have two problems here. I completely agree that we have to > do complete and thorough checks of each file descriptor at > sys_checkpoint(). Any checks made at other times should not be trusted. > > The other side is what Ingo has been asking for. How do we *know* when > we are checkpointable *before* we call (and without calling) This "without calling checkpoint(2)" results in much complications as demonstrated. task_struct and file are not like other structures because they are exposed in /proc. For PROC_FS=n kernels, one can't even check. You can do checkpoint(2) without actual dump. You pass, you're most certainly checkpointable (with inevitable race condition in mind). With time the amount of stuff C/R won't support will approach zero, but the infrastructure for "checkpointable" will stay constant. If it's too much right now, it will be way too much in future. > sys_checkpoint()? You are yet to acknowledge that this is a valid use > case, but it is exactly what Ingo is asking for, I believe. It's a valid requirement. > If nice printk()s are sufficient to cover what Ingo wants, I'm quite > happy to remove the /proc files. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
