[Crash-utility] [PATCH v2] Fix kmem failing to print task context when address is vmalloced stack
Tao Liu
ltao at redhat.com
Thu Sep 1 05:52:38 UTC 2022
Hi Kazu,
I see 3 out of 4 patches I posted upstream have been merged, could you
please help to merge this patch as well? Thank you very much!
Thanks,
Tao Liu
On Mon, Aug 29, 2022 at 3:21 PM HAGIO KAZUHITO(萩尾 一仁)
<k-hagio-ab at nec.com> wrote:
>
> 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 at 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 at 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);
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