Is the patch posted in comment #1 only needed in 16.04? Also, can you post a comment here when the patch gets accepted upstream?
** Tags added: kernel-da-key -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1761674 Title: [Ubuntu 16.04] kernel: fix rwlock implementation Status in Ubuntu on IBM z Systems: Triaged Status in linux package in Ubuntu: Triaged Bug description: Description: kernel: fix rwlock implementation Symptom: Kernel hangs, due to deadlock on an rwlock. Problem: With upstream commit 94232a4332de ("s390/rwlock: improve writer fairness") rwlock writer fairness was supposed to be implemented. If a writer tries to take an rwlock it sets unconditionally the writer bit within the lock word and waits until all readers have released the lock. This however can lead to a deadlock since rwlocks can be taken recursively by readers. If e.g. CPU 0 holds the lock as a reader, and CPU 1 wants to write-lock the lock, then CPU 1 sets the writer bit and afterwards busy waits for CPU 0 to release the lock. If now CPU 0 tries to read-lock the lock again (recursively) it will also busy wait until CPU 1 removes the writer bit, which will never happen, since it waits for the first reader on CPU 0 to release the lock. Solution: Revert the rwlock writer fairness semantics again. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1761674/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
