This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed- bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed- bionic'.
If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: verification-needed-bionic -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-aws in Ubuntu. https://bugs.launchpad.net/bugs/1926184 Title: locking/qrwlock: Fix ordering in queued_write_lock_slowpath() Status in linux package in Ubuntu: In Progress Status in linux-aws package in Ubuntu: In Progress Status in linux source package in Bionic: New Status in linux-aws source package in Bionic: Fix Committed Status in linux source package in Focal: New Status in linux-aws source package in Focal: New Status in linux source package in Groovy: New Status in linux-aws source package in Groovy: New Status in linux source package in Hirsute: New Status in linux-aws source package in Hirsute: New Bug description: [Impact] * Out of order reads can fetch a NULL pointer causing a kernel crash. Affects kernels from v4.15 to v5.11. [Fix] * commit 84a24bf8c52e ("locking/qrwlock: Fix ordering in queued_write_lock_slowpath()") * For Bionic, we also require an additional patch: commit fcfdfe30e324 ("locking/barriers: Introduce smp_cond_load_relaxed() and atomic_cond_read_relaxed()") [Where problems could occur] * This is quite a subtle bug. It is more prevalent on arm64. Regression possibility seems quite low. The worst impact could be a minor performance degradation. * Kernels 4.15 / 5.4 / 5.8 / 5.11 were successfully built and booted with this patch. Also, by using ftrace we could see that the changed function was executed with success multiple times. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1926184/+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
