2:28 a.m.
Hi, Tao
Thank you for the fix.
On Thu, Aug 25, 2022 at 8:00 PM <crash-utility-request(a)redhat.com> wrote:
Date: Thu, 25 Aug 2022 14:42:45 +0800
From: Tao Liu <ltao(a)redhat.com>
To: crash-utility(a)redhat.com
Subject: [Crash-utility] [PATCH v2] Fix kmem failing to print task
context when address is vmalloced stack
Message-ID: <20220825064243.71447-1-ltao(a)redhat.com>
Content-Type: text/plain; charset="US-ASCII"; x-default=true
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
I have one question: If the given physical address falls in the vmalloc
area, it won't print the task context, is that expected? For example:
[1] Before this patch: the "kmem + physical/virtual address" has the same
output asbelow.
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
crash> kmem 1883700e28 <----- vtop 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
[2] After this patch: the "kmem + physical/virtual address" has different
output asbelow.
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
crash> kmem 1883700e28 <----- vtop 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
Thanks.
Lianbo
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.
---
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);
--
2.33.1
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