On 2019-12-13 11:08:35 [+0200], John Mathew wrote: > > I was able to reproduce the warning on v5.2.21-rt14 which is the > latest tag on the rt-devel branch. > Here is my analysis. > What I see is that in crypto/algboss.c there is a probe being > scheduled when a notification arrives. > The probe will run a thread: cryptomgr_probe and wait for its completion. > The issue arises because a similar module is also issues a wait for > completion on the exactly same completion object (larval->completion). > The similar module is: crypto_larval_wait in linux-rt-devel/crypto/api.c > It is casting a crypto_larval struct pointer from a crypto_alg struct > pointer which doesn't seem to have/init a completion object. It should. container_of() statement would be better. > So it is actually the cryptomgr_probe thread that actually completes > both its own and the crypto_larval_wait waits and so the number of > completions exceeds the limit of 2. > > This looks like an error to me. Why? So multiple threads request a specific algorithm. This is synchronized into one request which (once complete) invokes complete_all() to wake all requesting threads. So this does not sound bad. I compiled and tested the syzkaller testcase but still no luck. Is there something special to you .config? > So I created patch in the following email. > I don't think the issue is with the limit, rather a wrong usage of the > completion object. But why is there no other error? Like wrong list usage, uninitialized spin_lock, etc.? > > > -John Sebastian
