[Crash-utility] Re: Crash errors when using vtop command on the Linux kernel v6.14-rc1

Date: Mon, 17 Feb 2025 11:52:21 -0300 From: Anderson Nascimento <andersonc0d3(a)gmail.com&gt; Subject: [Crash-utility] Crash errors when using vtop command on the Linux kernel v6.14-rc1 To: devel(a)lists.crash-utility.osci.io Message-ID: <CANUJ=ykSypFt-CEzSXtoXvMThoD_Stpg2c95P= g5DW2CvS13ow(a)mail.gmail.com&gt; Content-Type: text/plain; charset="UTF-8" Hello all, I built the Linux kernel version 6.14-rc1 on Fedora 41 and the crash utility doesn't work as expected on it. Quickly investigating the issue, the commit below from last month changes a field in the struct dentry and it seems to be the reason for the errors I am seeing. dcache: back inline names with a struct-wrapped array of unsigned long https://github.com/torvalds/linux/commit/58cf9c383c5c686668082f83f7e0f3e0...

crash> vtop -c 1224 0x41400000 VIRTUAL PHYSICAL 41400000 51144000 PGD: 24438000 => dfaf067 PUD: dfaf008 => 109fd067 PMD: 109fd050 => fc07067 PTE: fc07000 => 8000000051144867 PAGE: 51144000 PTE PHYSICAL FLAGS 8000000051144867 51144000 (PRESENT|RW|USER|ACCESSED|DIRTY|NX) VMA START END FLAGS FILE vtop: invalid structure member offset: dentry_d_iname FILE: filesys.c LINE: 3242 FUNCTION: get_pathname_component() BFD: /usr/bin/crash: unknown type [0x13] section `.relr.dyn' [/usr/bin/crash] error trace: 556181a34180 => 556181a331c5 => 556181a76b10 => 556181b4adab BFD: /usr/bin/crash: unknown type [0x13] section `.relr.dyn' vtop: invalid structure member offset: dentry_d_iname FILE: filesys.c LINE: 3242 FUNCTION: get_pathname_component() crash> I replaced the field name to reflect the change on Linux kernel 6.14-rc1 and it seems to work without any errors, but I am not used to the crash code base and I didn't check the commit in details to make sure there aren't more issues affecting it. I'd say

errors on newer Linux kernel versions. The command I was using and resulted in error works fine now, but as I said, there might be more changes in order to really support the Linux kernel v6.14. $ sudo ./crash_modified/crash ~/work/kernels/packages/linux_upstream_6.14_rc1/vmlinux crash 8.0.6++ Copyright (C) 2002-2025 Red Hat, Inc. Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation Copyright (C) 1999-2006 Hewlett-Packard Co Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited Copyright (C) 2006, 2007 VA Linux Systems Japan K.K. Copyright (C) 2005, 2011, 2020-2024 NEC Corporation Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc. Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc. Copyright (C) 2015, 2021 VMware, Inc. This program is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Enter "help copying" to see the conditions. This program has absolutely no warranty. Enter "help warranty" for details. GNU gdb (GDB) 10.2 Copyright (C) 2021 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later < http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-pc-linux-gnu". Type "show configuration" for configuration details. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>;. For help, type "help". Type "apropos word" to search for commands related to "word"... KERNEL: /home/user/work/kernels/packages/linux_upstream_6.14_rc1/vmlinux DUMPFILE: /proc/kcore CPUS: 4 DATE: Wed Dec 31 21:00:00 -03 1969 UPTIME: 07:44:59 LOAD AVERAGE: 0.40, 0.11, 0.03 TASKS: 306 NODENAME: fedoraserver41research RELEASE: 6.14.0-rc1 VERSION: #1 SMP PREEMPT_DYNAMIC Wed Feb 12 00:07:46 -03 2025 MACHINE: x86_64 (2995 Mhz) MEMORY: 2 GB PID: 47350 COMMAND: "crash" TASK: ffff88801eeb8000 [THREAD_INFO: ffff88801eeb8000] CPU: 3 STATE: TASK_RUNNING (ACTIVE) crash> vtop -c 1224 0x41400000 VIRTUAL PHYSICAL 41400000 51144000 PGD: 24438000 => dfaf067 PUD: dfaf008 => 109fd067 PMD: 109fd050 => fc07067 PTE: fc07000 => 8000000051144867 PAGE: 51144000 PTE PHYSICAL FLAGS 8000000051144867 51144000 (PRESENT|RW|USER|ACCESSED|DIRTY|NX) VMA START END FLAGS FILE ffff888006b52b00 41400000 42800000 8100073 PAGE PHYSICAL MAPPING INDEX CNT FLAGS ffffea0001445100 51144000 ffff88801440f361 41400 1 fffffd0020828 uptodate,lru,owner_2,swapbacked crash> vtop -c 1224 7f058fbc2000 VIRTUAL PHYSICAL 7f058fbc2000 3f278000 PGD: 244387f0 => 8955067 PUD: 89550b0 => 997b067 PMD: 997b3e8 => 9b69067 PTE: 9b69e10 => 800000003f278025 PAGE: 3f278000 PTE PHYSICAL FLAGS 800000003f278025 3f278000 (PRESENT|USER|ACCESSED|NX) VMA START END FLAGS FILE ffff88800ea17b00 7f058fbc2000 7f058fbc3000 8000071 /usr/lib64/libc.so.6 PAGE PHYSICAL MAPPING INDEX CNT FLAGS ffffea0000fc9e00 3f278000 ffff88800bf099c8 0 226 fffffe600426c referenced,uptodate,lru,workingset,private,head crash> The patch: $ git diff crash/filesys.c crash_modified/filesys.c diff --git a/crash/filesys.c b/crash_modified/filesys.c index 406ebb2..4759fa2 100644 --- a/crash/filesys.c +++ b/crash_modified/filesys.c @@ -2050,7 +2050,7 @@ vfs_init(void) MEMBER_OFFSET_INIT(dentry_d_parent, "dentry", "d_parent"); MEMBER_OFFSET_INIT(dentry_d_covers, "dentry", "d_covers"); MEMBER_OFFSET_INIT(dentry_d_name, "dentry", "d_name"); - MEMBER_OFFSET_INIT(dentry_d_iname, "dentry", "d_iname"); + MEMBER_OFFSET_INIT(dentry_d_iname, "dentry", "d_shortname"); MEMBER_OFFSET_INIT(dentry_d_sb, "dentry", "d_sb"); MEMBER_OFFSET_INIT(inode_i_mode, "inode", "i_mode"); MEMBER_OFFSET_INIT(inode_i_op, "inode", "i_op"); Nevertheless, I am bringing this issue to the list for the people responsible for the crash development to implement the proper support for the Linux kernel v6.14. Thank you. Regards, Anderson Nascimento https://blog.andersonc0d3.io