[Crash-utility] Re: [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 …… …… 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 <sachinp(a)linux.ibm.com&gt; Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com&gt; --- 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);