On 04/05/2020 19:12, Jens Axboe wrote: > On 5/3/20 6:52 AM, Pavel Begunkov wrote: >> On 30/04/2020 17:52, Jens Axboe wrote: >>> On 4/29/20 6:47 PM, Bijan Mottahedeh wrote: >>>> Use ctx->fallback_req address for test_and_set_bit_lock() and >>>> clear_bit_unlock(). >>> >>> Thanks, applied. >>> >> >> How about getting rid of it? As once was fairly noticed, we're screwed in many >> other ways in case of OOM. Otherwise we at least need to make async context >> allocation more resilient. > > Not sure how best to handle it, it really sucks to have things fall apart > under high memory pressure, a condition that isn't that rare in production > systems. But as you say, it's only a half measure currently. We could have > the fallback request have req->io already allocated, though. That would > provide what we need for guaranteed forward progress, even in the presence > of OOM conditions. Good idea. +extend it to work with links as a next step. E.g. for short links (2-3 reqs). -- Pavel Begunkov
