[Crash-utility] Re: [PATCH] Revert "vmcoreinfo: read vmcoreinfo using 'vmcoreinfo_data' when unavailable in elf note"

Sorry I forgot to cc Aditya. Adding Aditya in the thread. On Wed, Nov 19, 2025 at 5:09 PM Tao Liu <ltao(a)redhat.com&gt; wrote: > This patch will cause a regression on some x86_64 vmcores. > > $ crash -s vmcore vmlinux.gz > WARNING: vmcoreinfo is empty, will read from symbols > crash: cannot malloc vmcoreinfo buffer > crash: /var/tmp/vmlinux.gz_fWV3kA and vmcore do not match! > > The root cause is, in main.c, is_kdump() calls is_netdump(), which will > set pc->read_vmcoreinfo as vmcoreinfo_read_from_memory(), rather than > original vmcoreinfo_read_string(). > > Later in machdep_init(PRE_SYMTAB), vmcoreinfo_read_from_memory() doesn't > get "relocate" string, so fails for set kaslr flag, then fails for > linux_banner detection: > > Thread 1 "crash" hit Breakpoint 2, verify_version (): > 1096 if (!IS_KVADDR(linux_banner)) > (gdb) p/x linux_banner > $4 = 0xffffffff81e00100 > > crash> sym linux_banner > ffffffff9aa00100 (R) linux_banner > > As we can see with the patch applied, linux_banner got a wrong address. > So this patch currently is unsafe, and should be reverted before the fix. > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > --- > > Since it is too close to the new release date of crash utility, I don't > have enough time for full root cause analysis and re-testing. So currently > the best option is to revert it for now, and fix it in the next release then > re-apply.