[Crash-utility] [PATCH] get vmalloc start address from vmcoreinfo
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
……
……
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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 <sachinp(a)linux.ibm.com>
Signed-off-by: Aditya Gupta <adityag(a)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