** Tags added: cscc -- 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/1823753
Title: arm64: cma_alloc errors at boot Status in linux package in Ubuntu: Fix Released Status in linux source package in Disco: Fix Released Status in linux source package in Eoan: Fix Released Bug description: [Impact] We enabled CONFIG_DMA_CMA to fix bug 1803206, but that led to a regression on other arm64 systems that began spewing these messages on boot - sometimes > 10K of them: [ 19.534097] cma: cma_alloc: alloc failed, req-size: 64 pages, ret: -12 [ 19.534109] cma: cma_alloc: alloc failed, req-size: 16 pages, ret: -12 [ 19.534113] cma: cma_alloc: alloc failed, req-size: 64 pages, ret: -12 [ 19.534126] cma: cma_alloc: alloc failed, req-size: 16 pages, ret: -12 [ 19.534130] cma: cma_alloc: alloc failed, req-size: 64 pages, ret: -12 [ 19.534142] cma: cma_alloc: alloc failed, req-size: 16 pages, ret: -12 [ 19.534146] cma: cma_alloc: alloc failed, req-size: 64 pages, ret: -12 [ 19.534157] cma: cma_alloc: alloc failed, req-size: 16 pages, ret: -12 [ 19.534161] cma: cma_alloc: alloc failed, req-size: 64 pages, ret: -12 [ 19.534173] cma: cma_alloc: alloc failed, req-size: 16 pages, ret: -12 [ 19.534177] cma: cma_alloc: alloc failed, req-size: 64 pages, ret: -12 In a previous SRU (bug 1828092), we worked around this by just rate- limiting these messages. These are "err" priority messages though, so even a lower number of them is still disconcerting. [Fix] 1) Bump up the amount of available CMA on arm64 to 32M (same as upstream defconfig) 2) A patch-set from linux-next that redirects dma-direct contiguous allocations to alloc_pages() for single page allocations (single pages are by definition contiguous), avoiding CMA usage/fragmentation. [Test Case] dmesg | grep "cma_alloc: alloc failed" Some system configs will still have some of these errors even after this fix - but this should reduce them significantly. Per-driver optimizations can be used to make further improvements, but we should track those in other bugs. [Regression Risk] Tested on a HiSilicon D06 and HP m400 (Hi1620 & X-Gene arm64). Regression tested on: - Raspberry Pi 3B (see Comment #22) - Power9 system (ppc64el) - z/VM instance (s390x) - Intel Centerton system (amd64) Test builds are staged at http://ppa.launchpad.net/~dannf/ubuntu/cma To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1823753/+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
