On 3/11/24 7:09 PM, Christoph Hellwig wrote: > On Mon, Mar 11, 2024 at 08:28:50PM -0400, Mike Snitzer wrote: >> All for Jens being made to suffer with dm-crypt but I think we need a >> proper root cause of what is happening for you and Johannes ;) > > I'm going to try to stay out of the cranking, but I think the reason is > that the limits stacking inherits the max_segment_size, nvme has weird > rules for them due their odd PRPs, and dm-crypt set it's own > max_segment_size to split out each page. The regression here is > that we now actually verify that conflict. > > So this happens only for dm-crypt on nvme. The fix is probably > to not inherit low-level limits like max_segment_size, but I need > to think about it a bit more and come up with an automated test case > using say nvme-loop. That does seem like the most plausible explanation, I'm just puzzled why nobody hit it before it landed in Linus's tree. I know linux-next isn't THAT well runtime tested, but still. That aside, obviously the usual test cases should've hit it. Unless that was all on non-nvme storage, which is of course possible. > So for now the revert is the right thing. Yup -- Jens Axboe
