Re: [Crash-utility] [PATCH v3 3/3] Let kmem print task context when physical address is vmalloced stack

Tuesday, 6 September 2022

Hi, Tao
Thank you for the update.

On Mon, Sep 5, 2022 at 8:00 PM <crash-utility-request(a)redhat.com&gt; wrote:

...
 Date: Mon,  5 Sep 2022 15:09:22 +0800
 From: Tao Liu <ltao(a)redhat.com&gt;
 To: crash-utility(a)redhat.com
 Subject: [Crash-utility] [PATCH v3 3/3] Let kmem print task context
         when physical address is vmalloced stack
 Message-ID: <20220905070922.14426-4-ltao(a)redhat.com&gt;
 Content-Type: text/plain; charset="US-ASCII"; x-default=true

 Patch [1] enables kmem to print task context if the given virtual
 address is a vmalloced stack.

 This patch handles the same issue except the given address is
 physical address.
 Before:
...
     crash> kmem 1883700e28
        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 1883700e28
         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

 [1]:
 https://listman.redhat.com/archives/crash-utility/2022-August/010074.html

 I did the test and got different results with yours as below. Did I miss
anything else?

crash> kmem ffff94e088110000
CACHE             OBJSIZE  ALLOCATED     TOTAL  SLABS  SSIZE  NAME
ffff94e080c22a00    12040       3126      3129   3129    16k  task_struct
  SLAB              MEMORY            NODE  TOTAL  ALLOCATED  FREE
  ffffdd27c4204400  ffff94e088110000     0      1          1     0
  FREE / [ALLOCATED]
  [ffff94e088110000]

    PID: 0
COMMAND: "swapper/2"
   TASK: ffff94e088110000  (1 of 96)  [THREAD_INFO: ffff94e088110000]
    CPU: 2
  STATE: TASK_RUNNING (ACTIVE)

      PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS
ffffdd27c4204400  108110000 ffff94e080c22a00        0  1 10000000008100
slab,head

crash> kmem 108110000
CACHE             OBJSIZE  ALLOCATED     TOTAL  SLABS  SSIZE  NAME
ffff94e080c22a00    12040       3126      3129   3129    16k  task_struct
  SLAB              MEMORY            NODE  TOTAL  ALLOCATED  FREE
  ffffdd27c4204400  ffff94e088110000     0      1          1     0
  FREE / [ALLOCATED]
  [ffff94e088110000]

      PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS
ffffdd27c4204400  108110000 ffff94e080c22a00        0  1 10000000008100
slab,head
crash>

Thanks
Lianbo

Signed-off-by: Tao Liu <ltao(a)redhat.com&gt;
...
 ---
  memory.c | 4 ++++
  1 file changed, 4 insertions(+)

 diff --git a/memory.c b/memory.c
 index 1b6f9ba..eac8262 100644
 --- a/memory.c
 +++ b/memory.c
 @@ -13506,6 +13506,10 @@ kmem_search(struct meminfo *mi)
                 mi->flags &= ~GET_PHYS_TO_VMALLOC;

                 if (mi->retval) { 
+                       if ((task = stkptr_to_task(mi->retval)) && (tc =
...
 task_to_context(task))) {
 +                               show_context(tc);
 +                               fprintf(fp, "\n");
 +                       }
                         if ((sp = value_search(mi->retval, &offset))) {
                                 show_symbol(sp, offset,
                                         SHOW_LINENUM | SHOW_RADIX());
 --
 2.33.1

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