> Il giorno 06 feb 2018, alle ore 08:56, Mike Galbraith <efault@xxxxxx> ha scritto: > > On Tue, 2018-02-06 at 08:44 +0100, Oleksandr Natalenko wrote: >> Hi, Paolo. >> >> I can confirm that this patch fixes cfdisk hang for me. I've also tried >> to trigger the issue Mike has encountered, but with no luck (maybe, I >> wasn't insistent enough, just was doing dd on usb-storage device in the >> VM). > > I was doing kbuilds, and it blew up on me twice. Switching back to cfq > seemed to confirm it was indeed the patch causing trouble, but that's > by no means a certainty. > Hi Mike, as you can imagine, I didn't get any failure in my pre-submission tests on this patch. In addition, it is not that easy to link this patch, which just adds some internal bfq housekeeping in case of a requeue, with a corruption of external lists for general I/O management. In this respect, as Oleksandr comments point out, by switching from cfq to bfq, you switch between much more than two schedulers. Anyway, who knows ... Maybe this report will ring a bell with some block-layer expert, or, hopefully, next feedback will help puzzle this out. Thanks, Paolo > -Mike
