On Mon, Mar 20, 2023 at 05:00:13PM -0300, Luis Claudio R. Goncalves wrote: > On Mon, Mar 20, 2023 at 03:37:31PM -0400, Joe Korty wrote: > > In the transition from 5.10.158-rt77 to 5.10.162-rt78, > > the initialization of task_struct::wake_q_sleeper.next > > was dropped. Restore it. > > > > This appears to be only a problem in 5.10. 5.15 does not > > have wake_q_sleeper; 4.19 does have it but its initialization > > there is still present. > > > > The 5.10.162-rt78 patch that damaged fork.c is: > > > > 0170-locking-rtmutex-add-sleeping-lock-implementation.patch > > > > I do not have a simple test that brings out this problem. > > My test consists of a shell script and eight binaries, > > all of which were written in Ada. strace shows that it > > does a few thousand forks in rapid succession. One of the > > forks stalls out, after which no fork after that returns. > > Eventually the 122 second stallout occurs and a large > > number of threads are shown to be waiting for tasklist > > lock, either in do_exit or in copy_process. The kernel > > .config has rt and many debug features enabled, lockdep > > included. > > Joe, thank you for investigating that problem and for writing a patch. > > Earlier today Steffen Dirkwinkel sent a similar patch: > > https://lore.kernel.org/all/20230320080347.32434-1-linux@xxxxxxxxxx/ > > Would you mind giving your ACK to his patch? I have that patch queued for > my next build already. Acked-by: Joe Korty <joe.korty@xxxxxxxxxxxxxxxxx>
