Hi, Lucas
Thank you for the fix.
On Tue, Dec 17, 2024 at 12:14 PM <devel-requ...@lists.crash-utility.osci.io>
wrote:
> Date: Sat, 14 Dec 2024 18:01:14 -0500
> From: Lucas Oakley <soak...@redhat.com>
> Subject: [Crash-utility] [PATCH] Fix incorrect 'bt -v' output
> suggesting overflow
> To: devel@lists.crash-utility.osci.io
> Message-ID: <20241214230114.2854910-1-soak...@redhat.com>
> Content-Type: text/plain; charset="US-ASCII"; x-default=true
>
> Change check_stack_overflow() to check if the thread_info's cpu
> member is smaller than possible existing CPUs, rather than the
> kernel table's cpu number (kt->cpus). The kernel table's cpu number
> is changed on some architectures to reflect the highest numbered
> online cpu + 1. This can cause a false positive in
> check_stack_overflow() if the cpu member of a parked task's
> thread_info structure, assigned to an offlined cpu, is larger than
> the kt->cpus but lower than the number of existing logical cpus.
> An example of this is RHEL 7 on s390x or RHEL 8 on ppc64le when
> the highest numbered CPU is offlined.
>
> Signed-off-by: Lucas Oakley <soak...@redhat.com>
> ---
> task.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/task.c b/task.c
> index 33de7da..93dab0e 100644
> --- a/task.c
> +++ b/task.c
> @@ -11253,12 +11253,12 @@ check_stack_overflow(void)
> cpu = 0;
> break;
> }
> - if (cpu >= kt->cpus) {
> + if (cpu >= get_cpus_present()) {
> if (!overflow)
> print_task_header(fp, tc, 0);
> fprintf(fp,
> " possible stack overflow:
> thread_info.cpu: %d >= %d\n",
> - cpu, kt->cpus);
> + cpu, get_cpus_present());
> overflow++; total++;
> }
> }
>
To avoid calling get_cpus_present() twice, I would tend to modify it as
below:
diff --git a/task.c b/task.c
index 33de7da2a692..49f771e275c1 100644
--- a/task.c
+++ b/task.c
@@ -11238,6 +11238,8 @@ check_stack_overflow(void)
}
if (VALID_MEMBER(thread_info_cpu)) {
+ int cpus = get_cpus_present();
+
switch (cpu_size)
{
case 1:
@@ -11253,12 +11255,12 @@ check_stack_overflow(void)
cpu = 0;
break;
}
- if (cpu >= kt->cpus) {
+ if (cpu >= cpus) {
if (!overflow)
print_task_header(fp, tc, 0);
fprintf(fp,
" possible stack overflow:
thread_info.cpu: %d >= %d\n",
- cpu, kt->cpus);
+ cpu, cpus);
overflow++; total++;
}
}
What do you think?
Lianbo
--
> 2.47.1
>
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