Thanks a lot Cascardo and Dann - very good points. Cascardo: I agree with you, I misunderstood and didn't consider the minor kernel releases. I think that Dann's idea of testing makes it much simpler though. Maybe kernel team could create the vmcore images, as part of the release process, for some random kernels (like generic + 3 cloud kernels randomly) and "dump" into this server. So, makedumpfile test infrastructure would then consume the vmcores and execute the test, checking against bugs/regressions. The test could be quite simple, just checking return value of makedumpfile and if the file created is in fact a compressed dump (the "file" tool could be used by that).
I agree with you as well Dann, makedumpfile is much more important than the crash tool and should have priority. Also, testing makedump is easier than checking the crash tool I guess heheh Cheers! -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to makedumpfile in Ubuntu. https://bugs.launchpad.net/bugs/1970672 Title: makedumpfile falls back to cp with "__vtop4_x86_64: Can't get a valid pmd_pte." Status in makedumpfile package in Ubuntu: New Bug description: [Impact] * On Focal with an HWE (>=5.12) kernel, makedumpfile can sometimes fail with "__vtop4_x86_64: Can't get a valid pmd_pte." * makedumpfile falls back to cp for the dump, resulting in extremely large vmcores. This can impact both collection and analysis due to lack of space for the resulting vmcore. * This is fixed in upstream commit present in versions 1.7.0 and 1.7.1: https://github.com/makedumpfile/makedumpfile/commit/646456862df8926ba10dd7330abf3bf0f887e1b6 commit 646456862df8926ba10dd7330abf3bf0f887e1b6 Author: Kazuhito Hagio <k-hagio...@nec.com> Date: Wed May 26 14:31:26 2021 +0900 [PATCH] Increase SECTION_MAP_LAST_BIT to 5 * Required for kernel 5.12 Kernel commit 1f90a3477df3 ("mm: teach pfn_to_online_page() about ZONE_DEVICE section collisions") added a section flag (SECTION_TAINT_ZONE_DEVICE) and causes makedumpfile an error on some machines like this: __vtop4_x86_64: Can't get a valid pmd_pte. readmem: Can't convert a virtual address(ffffe2bdc2000000) to physical address. readmem: type_addr: 0, addr:ffffe2bdc2000000, size:32768 __exclude_unnecessary_pages: Can't read the buffer of struct page. create_2nd_bitmap: Can't exclude unnecessary pages. Increase SECTION_MAP_LAST_BIT to 5 to fix this. The bit had not been used until the change, so we can just increase the value. Signed-off-by: Kazuhito Hagio <k-hagio...@nec.com> [Test Plan] * Confirm that makedumpfile works as expected by triggering a kdump. * Confirm that the patched makedumpfile works as expected on a system known to experience the issue. * Confirm that the patched makedumpfile is able to work with a cp- generated known affected vmcore to compress it. The unpatched version fails. [Where problems could occur] * This change could adversely affect the collection/compression of vmcores during a kdump situation resulting in fallback to cp. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/makedumpfile/+bug/1970672/+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
