The crash is due to the incorrect implementation of the copy_to_user potion's abort handler zeroing out destination buffers. The code has been corrected by forking different handlers for copy_from and copy_to user source files. We have a test that runs specweb, iperf and fio that reproduce the crash immediately. The new patch attached has ran the same test for over 50 hours without issues. I have also attached both the crash log and the non crashing log as well.
** Patch added: "New copy to/from optimization" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1400349/+attachment/4276593/+files/0001-arm64-optimized-copy_to_user-and-copy_from_user-asse.patch -- 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/1400349 Title: [SRU] new arm64 optimized copy_to_user and copy_from_user assembly code Status in linux package in Ubuntu: Confirmed Bug description: [Impact] The copy_{to,from}_user implementations in the Ubuntu kernel are suboptimal. Optimized implementations have been submitted upstream and have shown a significant improvement in network performance. [Test Case] Generate traffic from one node to another using iperf. [Regression Risk] These functions are obviously used heavily throughout the kernel, so a defect here could have significant impact. This risk is mitigated by using an implementation heavily based on the linaro string libraries (which are used in other places already, e.g. glibc), and through active testing of this patch on real hardware using a trusty-kernel base. The new patch will also undergo regression testing to ensure the memory corruption issue of the previous patch does not exist. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1400349/+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