Bionic SRU request submitted: https://lists.ubuntu.com/archives/kernel-team/2018-September/095678.html
** Description changed: - == Comment: #0 - Michael Ranweiler <mranw...@us.ibm.com> - 2018-09-10 - 19:26:14 == + == SRU Justification == + Due to a recent change for powernv, now the total GPU memory is no longer + available. This impacts performance for any application/benchmark has a + large GPU memory utilization. + + IBM is requesting mainlien commit 7acf50e4efa6 in Bionic, which reverts + mainline commit 4b5d62ca17a1. + + == Fix == + 7acf50e4efa6 ("Revert "powerpc/powernv: Increase memory block size to 1GB on radix"") + + == Regression Potential == + Low. This is a revert that was also done upstream due to a regression. + Limited to powerpc. + + == Test Case == + A test kernel was built with this patch and tested by the original bug reporter. + The bug reporter states the test kernel resolved the bug. + + + + + + == Comment: #0 - Michael Ranweiler <mranw...@us.ibm.com> - 2018-09-10 19:26:14 == Due to a recent change for powernv, now the total GPU memory is no longer available. This impacts performance for any application/benchmark has a large GPU memory utilization. - Previous amount of memory : 16128MiB - Current amount of available memory : 15360MiB + Previous amount of memory : 16128MiB + Current amount of available memory : 15360MiB - From Anton, describing the recent change.: - powerpc/powernv: Increase memory block size to 1GB on radix - - Memory hot unplug on PowerNV radix hosts is broken. Our memory block - size is 256MB but since we map the linear region with very large - pages, each pte we tear down maps 1GB. - - A hot unplug of one 256MB memory block results in 768MB of memory - getting unintentionally unmapped. At this point we are likely to oops. - - Fix this by increasing our memory block size to 1GB on PowerNV radix - hosts. - - Fixes: 4b5d62ca17a1 ("powerpc/mm: add radix__remove_section_mapping()") + From Anton, describing the recent change.: + powerpc/powernv: Increase memory block size to 1GB on radix + Memory hot unplug on PowerNV radix hosts is broken. Our memory block + size is 256MB but since we map the linear region with very large + pages, each pte we tear down maps 1GB. + + A hot unplug of one 256MB memory block results in 768MB of memory + getting unintentionally unmapped. At this point we are likely to oops. + + Fix this by increasing our memory block size to 1GB on PowerNV radix + hosts. + + Fixes: 4b5d62ca17a1 ("powerpc/mm: add + radix__remove_section_mapping()") This is fixed with: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7acf50e4efa6 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1792102 Title: Ubuntu18.04: GPU total memory is reduced To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/1792102/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs