> On Sep 12, 2021, at 11:15 AM, Jens Axboe <axboe@xxxxxxxxx> wrote: > > On 9/11/21 8:34 PM, Nadav Amit wrote: >> Hello Jens (& Pavel), >> >> I hope you are having a nice weekend. I ran into a KASAN failure in io-uring >> which I think is not "my fault". >> >> The failure does not happen very infrequently, so my analysis is based on >> reading the code. IIUC the failure, then I do not understand the code well >> enough, as to say I do not understand how it was supposed to work. I would >> appreciate your feedback. >> >> The failure happens on my own custom kernel (do not try to correlate the line >> numbers). The gist of the splat is: > > I think this is specific to your use case, but I also think that we > should narrow the scope for this type of REQ_F_REISSUE trigger. It > really should only happen on bdev backed regular files, where we cannot > easily pass back congestion. For that case, the completion for this is > called while we're in ->write_iter() for example, and hence there is no > race here. > > I'll ponder this a bit… I see what you are saying. The assumption is that write_iter() is setting REQ_F_REISSUE, which is not the case in my use-case. Perhaps EAGAIN is anyhow not the right return value (in my case). I am not sure any other “invalid" use-case exists, but some documentation/assertion(?) can help. I changed the return error-codes and check that the issue is not triggered again. Thanks, as usual, for the quick response.
