** Description changed: Testing failed on: - amd64: https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-bionic/bionic/amd64/l/lttng-modules/20200423_185643_adec8@/log.gz + amd64: https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-bionic/bionic/amd64/l/lttng-modules/20200423_185643_adec8@/log.gz + + [SRU Justification] + + == Impact == + + In linux 5.6 upstream replaced vmalloc_sync_all() by + vmalloc_sync_mappings() and vmalloc_sync_unmappings(). Lttng uses + vmalloc_sync_all() from a wrapper to prevent recursive page faults. The + call is either made directly in the code or, if kallsyms is available, + by looking up its address and then jumping indirectly. + + Recent stable updates backported that change into 4.4, 4.15, 5.3, and + 5.4. This affects lttng-modules. Either the build fails completely (if + kallsyms is not enabled). Or there will be warnings at runtime: + + LTTng: vmalloc_sync_all symbol lookup failed. + Page fault handler and NMI tracing might trigger faults. + + == Fix == + + The proposed fix would check the kernel header for vmalloc_sync_mappings + and if available, replace strings and calls with the correct function + name. + + == Testcase == + + Installation of lttng-modules-dkms, depending on kernel configuration + either the build will fail or loading lttng modules (tried lttng-probe- + rcu manually but on each reboot all modules seem to get loaded) will + produce above warning messages. + + == Regression Potential == + + Low, without the new function name present, everything would be + unchanged and once the change is there, functionality already is + regressed.
** Patch removed: "fix-vmalloc-sync-all.patch" https://bugs.launchpad.net/ubuntu/xenial/+source/lttng-modules/+bug/1874521/+attachment/5370973/+files/fix-vmalloc-sync-all.patch -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1874521 Title: lttng-modules 2.10.8-1ubuntu2~18.04.1 ADT test failure with linux-kvm 4.15.0-1059.60 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lttng-modules/+bug/1874521/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
