Filed this downstream: https://bugzilla.redhat.com/show_bug.cgi?id=986074 But our nouveau maintainer seems to be dormant at present, so filing upstream. Running Fedora 20 (pre-release), when I boot a non-debug kernel, my graphical rendering is mostly fine (minus a few little buglets I've been living with for years). When I boot a debug kernel, though, it's bad - not just sluggish, but bad. It seems like refreshes simply don't always work completely: say, I open a new tab in Firefox, but I can still see all the content from the previous tab until I wait several seconds or switch tabs and switch back or scrub my mouse around a bit. Any kind of window-switching operation tends to show the issue. A Fedora debug kernel build sets the following: @perl -pi -e 's/# CONFIG_SLUB_DEBUG_ON is not set/CONFIG_SLUB_DEBUG_ON=y/' config-nodebug @perl -pi -e 's/# CONFIG_LOCK_STAT is not set/CONFIG_LOCK_STAT=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_STACK_USAGE is not set/CONFIG_DEBUG_STACK_USAGE=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_SLAB is not set/CONFIG_DEBUG_SLAB=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_MUTEXES is not set/CONFIG_DEBUG_MUTEXES=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_WW_MUTEX_SLOWPATH is not set/CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_RT_MUTEXES is not set/CONFIG_DEBUG_RT_MUTEXES=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_LOCK_ALLOC is not set/CONFIG_DEBUG_LOCK_ALLOC=y/' config-nodebug @perl -pi -e 's/# CONFIG_PROVE_LOCKING is not set/CONFIG_PROVE_LOCKING=y/' config-nodebug @perl -pi -e 's/# CONFIG_PROVE_RCU is not set/CONFIG_PROVE_RCU=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_SPINLOCK is not set/CONFIG_DEBUG_SPINLOCK=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_VM is not set/CONFIG_DEBUG_VM=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAULT_INJECTION is not set/CONFIG_FAULT_INJECTION=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAILSLAB is not set/CONFIG_FAILSLAB=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAIL_PAGE_ALLOC is not set/CONFIG_FAIL_PAGE_ALLOC=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAIL_IO_TIMEOUT is not set/CONFIG_FAIL_IO_TIMEOUT=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAIL_MAKE_REQUEST is not set/CONFIG_FAIL_MAKE_REQUEST=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAIL_MMC_REQUEST is not set/CONFIG_FAIL_MMC_REQUEST=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAULT_INJECTION_DEBUG_FS is not set/CONFIG_FAULT_INJECTION_DEBUG_FS=y/' config-nodebug @perl -pi -e 's/# CONFIG_FAULT_INJECTION_STACKTRACE_FILTER is not set/CONFIG_FAULT_INJECTION_STACKTRACE_FILTER=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_SG is not set/CONFIG_DEBUG_SG=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_WRITECOUNT is not set/CONFIG_DEBUG_WRITECOUNT=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_OBJECTS is not set/CONFIG_DEBUG_OBJECTS=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_OBJECTS_FREE is not set/CONFIG_DEBUG_OBJECTS_FREE=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_OBJECTS_TIMERS is not set/CONFIG_DEBUG_OBJECTS_TIMERS=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_OBJECTS_WORK is not set/CONFIG_DEBUG_OBJECTS_WORK=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER is not set/CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_OBJECTS_RCU_HEAD is not set/CONFIG_DEBUG_OBJECTS_RCU_HEAD=y/' config-nodebug @perl -pi -e 's/# CONFIG_X86_PTDUMP is not set/CONFIG_X86_PTDUMP=y/' config-nodebug @perl -pi -e 's/# CONFIG_CAN_DEBUG_DEVICES is not set/CONFIG_CAN_DEBUG_DEVICES=y/' config-nodebug @perl -pi -e 's/# CONFIG_MODULE_FORCE_UNLOAD is not set/CONFIG_MODULE_FORCE_UNLOAD=y/' config-nodebug @perl -pi -e 's/# CONFIG_SYSCTL_SYSCALL_CHECK is not set/CONFIG_SYSCTL_SYSCALL_CHECK=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_NOTIFIERS is not set/CONFIG_DEBUG_NOTIFIERS=y/' config-nodebug @perl -pi -e 's/# CONFIG_DMA_API_DEBUG is not set/CONFIG_DMA_API_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_PM_TEST_SUSPEND is not set/CONFIG_PM_TEST_SUSPEND=y/' config-generic @perl -pi -e 's/# CONFIG_PM_ADVANCED_DEBUG is not set/CONFIG_PM_ADVANCED_DEBUG=y/' config-generic @perl -pi -e 's/# CONFIG_B43_DEBUG is not set/CONFIG_B43_DEBUG=y/' config-generic @perl -pi -e 's/# CONFIG_B43LEGACY_DEBUG is not set/CONFIG_B43LEGACY_DEBUG=y/' config-generic @perl -pi -e 's/# CONFIG_MMIOTRACE is not set/CONFIG_MMIOTRACE=y/' config-nodebug @perl -pi -e 's/CONFIG_STRIP_ASM_SYMS=y/# CONFIG_STRIP_ASM_SYMS is not set/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_CREDENTIALS is not set/CONFIG_DEBUG_CREDENTIALS=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_FORCE_WEAK_PER_CPU is not set/CONFIG_DEBUG_FORCE_WEAK_PER_CPU=y/' config-nodebug @perl -pi -e 's/# CONFIG_ACPI_DEBUG is not set/CONFIG_ACPI_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_EXT4_DEBUG is not set/CONFIG_EXT4_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_PERF_USE_VMALLOC is not set/CONFIG_DEBUG_PERF_USE_VMALLOC=y/' config-nodebug @perl -pi -e 's/# CONFIG_JBD2_DEBUG is not set/CONFIG_JBD2_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_NFSD_FAULT_INJECTION is not set/CONFIG_NFSD_FAULT_INJECTION=y/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_BLK_CGROUP is not set/CONFIG_DEBUG_BLK_CGROUP=y/' config-nodebug @perl -pi -e 's/# CONFIG_DRBD_FAULT_INJECTION is not set/CONFIG_DRBD_FAULT_INJECTION=y/' config-nodebug @perl -pi -e 's/# CONFIG_ATH_DEBUG is not set/CONFIG_ATH_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_CARL9170_DEBUGFS is not set/CONFIG_CARL9170_DEBUGFS=y/' config-nodebug @perl -pi -e 's/# CONFIG_IWLWIFI_DEVICE_TRACING is not set/CONFIG_IWLWIFI_DEVICE_TRACING=y/' config-nodebug @perl -pi -e 's/# CONFIG_DMADEVICES_DEBUG is not set/CONFIG_DMADEVICES_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_DMADEVICES_VDEBUG is not set/CONFIG_DMADEVICES_VDEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_CEPH_LIB_PRETTYDEBUG is not set/CONFIG_CEPH_LIB_PRETTYDEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_QUOTA_DEBUG is not set/CONFIG_QUOTA_DEBUG=y/' config-nodebug @perl -pi -e 's/# CONFIG_KGDB_KDB is not set/CONFIG_KGDB_KDB=y/' config-nodebug @perl -pi -e 's/# CONFIG_KDB_KEYBOARD is not set/CONFIG_KDB_KEYBOARD=y/' config-nodebug @perl -pi -e 's/# CONFIG_CPU_NOTIFIER_ERROR_INJECT is not set/CONFIG_CPU_NOTIFIER_ERROR_INJECT=m/' config-nodebug @perl -pi -e 's/# CONFIG_DEBUG_PER_CPU_MAPS is not set/CONFIG_DEBUG_PER_CPU_MAPS=y/' config-nodebug @perl -pi -e 's/# CONFIG_USB_UAS is not set/CONFIG_USB_UAS=m/' config-generic So that's the difference we're looking at. This is reproducible up to kernel-3.11.0-0.rc6.git1.2.fc20.x86_64 .
Does removing CONFIG_DEBUG_WW_MUTEX_SLOWPATH from the list of options enabled fix things? This option randomly injects failures into ww mutexes (now used for ttm)... dunno if that would be enough to cause your issues or not, but definitely worth trying without it.
Thanks for the suggestion. I'll try it out when I can find a couple hours to get a full kernel build done :)
No update in a year... most likely due to the ww mutex debug option. If that's not it and it still repros on recent kernels, feel free to reopen.
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