You have been subscribed to a public bug by Ioanna Alifieraki (joalif): [Impact]
On some arm systems makedumpfile fails to translate virtual to physical addresses properly. This may result in makedumpfile looping forever exhausting all memory, or translating a virtual address to an invalid physical address and then failing and falling back to cp. The reason it cannot resolve some addresses is because the PMD mask is wrong. When physical address mask allows up to 48bits pmd mask should allow the same, currently pmd mask is set to 40bits (see commit [1]). Commit [1] fixes this bug. [Test Case] To hit this bug you need a system that needs physical addresses over 1TB. This may be either because you have a lot of memory or because the firmware mapped some memory above 1TB for some reason [1]. A user hit this bug because firmware mapped memory above 1TB and provided a dump so I could reproduce the bug when running makedumpfile on the dump. [Regression Potential] This commit changes the PMD_SECTION_MASK for arm64. So any regression potential would only affect arm64 systems. In addition PMD_SECTION_MASK is used in translation from virtual to physical addresses and therefore any regression would happen during this process. [Other] [1] https://github.com/makedumpfile/makedumpfile/commit/7242ae4cb5288df626f464ced0a8b60fd669100b When testing kdump on Ubuntu 18.04.4 (arm64) GA kernel, makedumpfile fails. The test steps are as follows: # echo 1> / proc / sys / kernel / sysrq # echo c> / proc / sysrq-trigger The logs are as follows: kdump-tools[646]: starting kdump-tools: * running makedumpfile -c -d 31 /proc/vmcore /var/crash/202003251128/dump-incomplete kdump-tools[646]: readpage_elf: Attempt to read non-existent page at 0x0 kdump-tools[646]: readmem: type_addr: 1, addr:ff0, size:8 kdump-tools[646]: vaddr_to_paddr_arm64: Can't read pud kdump-tools[646]: readmem: Can't convert a virtual address(ffff9e653690) to physical address. kdump-tools[646]: readmem: type_addr: 0, addr:ffff9e653690, size:1032 kdump-tools[646]: validate_mem_section: Can't read mem_section array. kdump-tools[646]: get_mem_section: Could not validate mem_section. kdump-tools[646]: get_mm_sparsemem: Can't get the address of mem_section. kdump-tools[646]: makedumpfile Failed. kdump-tools[646]: * kdump-tools: makedumpfile failed, falling back to 'cp' But when I use the HWE kernel, I find that there is no such problem. The HEW kernel version: 5.3.0-42-generic ** Affects: linux (Ubuntu) Importance: Medium Assignee: Ioanna Alifieraki (joalif) Status: Confirmed ** Affects: linux (Ubuntu Xenial) Importance: Undecided Status: New ** Affects: linux (Ubuntu Bionic) Importance: Medium Assignee: Ioanna Alifieraki (joalif) Status: Confirmed ** Affects: linux (Ubuntu Eoan) Importance: Undecided Status: New ** Affects: linux (Ubuntu Focal) Importance: Undecided Status: New ** Affects: linux (Ubuntu Groovy) Importance: Medium Assignee: Ioanna Alifieraki (joalif) Status: Confirmed ** Affects: linux (Debian) Importance: Unknown Status: Unknown ** Tags: sts -- Kdump-Tools: Makedumpfile Failed, Falling Back To 'Cp' https://bugs.launchpad.net/bugs/1869465 You received this bug notification because you are a member of STS Sponsors, which is subscribed to the bug report. -- Mailing list: https://launchpad.net/~sts-sponsors Post to : [email protected] Unsubscribe : https://launchpad.net/~sts-sponsors More help : https://help.launchpad.net/ListHelp
