Re: [Crash-utility] [PATCH v2] Fix kmem failing to print task context when address is vmalloced stack
On 2022/08/25 15:42, 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.
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)
VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE
ffff94eb9102c640 ffff94eb9102b140 ffffb7efce9b8000 - ffffb7efce9bd000 20480
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffdd28220dc000 1883700000 0 0 1 50000000000000
Signed-off-by: Tao Liu <ltao(a)redhat.com>
---
v1 -> v2: 1) Remove goto to print task context and vmlist.
2) Update commit log to show the change.
Thanks for the update, looks good to me.
Acked-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Thanks,
Kazu
>
> ---
> memory.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/memory.c b/memory.c
> index 7339f0c..9ab5781 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -13477,6 +13477,10 @@ 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");
> + }
> if (kvtop(NULL, mi->spec_addr, &paddr, 0)) {
> mi->flags = orig_flags | VMLIST_VERIFY;
> dump_vmlist(mi);