Linus Torvalds writes: (Summary) wrote:
I think we might also look at just also handling the whole RSVD page fault case more gracefully.
fault case more gracefully.
The fact that we consider it a page table corruption and react in a fairly extreme manner to it sounds a bit excessive. Yes, that RSVD it clearly happens if we have page table corruption, but if we can trigger it other ways, we shouldn't necessarily just assume blindly that it's due to some horrible corruption.
that it's due to some horrible corruption.
So perhaps instead of trying to limit the mmap, see this as a testing opportunity for unusual fault handling, and not consider RSVD a "corrupted page tables" issue, but just treat it as a normal page fault (perhaps after validating that it's a /dev/mem mapping).
[...]
a check on the bus width (or some other fix)?I think we might also look at just also handling the whole RSVD page fault case more gracefully.
fault case more gracefully.
The fact that we consider it a page table corruption and react in a fairly extreme manner to it sounds a bit excessive. Yes, that RSVD it clearly happens if we have page table corruption, but if we can trigger it other ways, we shouldn't necessarily just assume blindly that it's due to some horrible corruption.
that it's due to some horrible corruption.
So perhaps instead of trying to limit the mmap, see this as a testing opportunity for unusual fault handling, and not consider RSVD a "corrupted page tables" issue, but just treat it as a normal page fault (perhaps after validating that it's a /dev/mem mapping).