On 2022/08/24 13:08, Tao Liu wrote: > When kernel enabled CONFIG_VMAP_STACK, stack can be allocated to > vmalloced area. Currently crash didn't handle the case, as a result, > kmem will not print the task context as expected. This patch fix the > bug by checking if the address is a vmalloced stack first. Good catch, again. Thank you for the patch. > > Before: > crash> kmem ffffb7efce9bbe28 > VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE > ffff94eb9102c640 ffff94eb9102b140 ffffb7efce9b8000 - ffffb7efce9bd000 20480 > > PAGE PHYSICAL MAPPING INDEX CNT FLAGS > ffffdd28220dc000 1883700000 0 0 1 50000000000000 > > After: > crash> kmem ffffb7efce9bbe28 > PID: 847 > COMMAND: "khungtaskd" > TASK: ffff94f8038f4000 [THREAD_INFO: ffff94f8038f4000] > CPU: 72 > STATE: TASK_RUNNING (PANIC) > > PAGE PHYSICAL MAPPING INDEX CNT FLAGS > ffffdd28220dc000 1883700000 0 0 1 50000000000000 I feel like it might be better to print the VMAP_AREA info too even if it's an address of process's stack. For example, crash> kmem ffff9b6dc017ff50 PID: 1 COMMAND: "systemd" TASK: ffff8f96c159c8c0 [THREAD_INFO: ffff8f96c159c8c0] CPU: 6 STATE: TASK_INTERRUPTIBLE VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE ffff8f96c7c25080 ffff8f96c7d48dc0 ffff9b6dc017c000 - ffff9b6dc0181000 20480 PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffff043bb9910c0 ee6443000 0 0 1 17ffffc0000000 So, can we remove the "goto mem_map;" below ?

Thanks, Kazu > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > --- > memory.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/memory.c b/memory.c > index 7339f0c..7a1bf9c 100644 > --- a/memory.c > +++ b/memory.c > @@ -13477,6 +13477,11 @@ kmem_search(struct meminfo *mi) > * Check for a valid mapped address. > */ > if ((mi->memtype == KVADDR) && IS_VMALLOC_ADDR(mi->spec_addr)) { > + if ((task = stkptr_to_task(vaddr)) && (tc = task_to_context(task))) { > + show_context(tc); > + fprintf(fp, "\n"); > + goto mem_map; > + } > if (kvtop(NULL, mi->spec_addr, &paddr, 0)) { > mi->flags = orig_flags | VMLIST_VERIFY; > dump_vmlist(mi);