Below error is noticed when running crash on vmcore collected from a linux-next
kernel crash (linux-next tag next-20240121):

    # crash /boot/vmlinuz-6.8.0-rc5-next-20240221 ./vmcore
    ……
    ……
    For help, type “help”.
    Type "apropos word" to search for commands related to "word"...

    crash: page excluded: kernel virtual address: c00000000219a2c0  type: 
“vmlist"

This occured since getting the vmalloc area base address doesn't work in
crash now, due to 'vmap_area_list' being removed in the linux kernel with
below commit (in linux-next tree):

    commit 378eb24a0658dd922b29524e0ce35c6c43f56cba
         mm/vmalloc: remove vmap_area_list

As an alternative, the commit introduced 'VMALLOC_START' in vmcoreinfo to
get base address of vmalloc area, use it to return vmallow start address
instead of depending on vmap_area_list and vmlist

Reported-by: Sachin Sant <sach...@linux.ibm.com>
Signed-off-by: Aditya Gupta <adit...@linux.ibm.com>
---
 memory.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/memory.c b/memory.c
index b84e974a3325..b3027bd101cd 100644
--- a/memory.c
+++ b/memory.c
@@ -17220,11 +17220,20 @@ first_vmalloc_address(void)
 {
        static ulong vmalloc_start = 0;
         ulong vm_struct, vmap_area;
+       char *vmalloc_start_string;
 
        if (DUMPFILE() && vmalloc_start)
                return vmalloc_start;
 
-       if (vt->flags & USE_VMAP_AREA) {
+       /*
+        * 'vmap_area_list' and 'vmlist' in newer kernels might be empty, prefer
+        * `VMALLOC_START` if exported in vmcoreinfo
+        */
+       vmalloc_start_string = pc->read_vmcoreinfo("NUMBER(VMALLOC_START)");
+       if (vmalloc_start_string) {
+               vmalloc_start = stol(vmalloc_start_string, QUIET, NULL);
+               free(vmalloc_start_string);
+       } else if (vt->flags & USE_VMAP_AREA) {
                get_symbol_data("vmap_area_list", sizeof(void *), &vmap_area);
                if (!vmap_area)
                        return 0;
-- 
2.43.2
--
Crash-utility mailing list -- devel@lists.crash-utility.osci.io
To unsubscribe send an email to devel-le...@lists.crash-utility.osci.io
https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/
Contribution Guidelines: https://github.com/crash-utility/crash/wiki

Reply via email to