Hi, Lucas
Thank you for the fix.
On Tue, Dec 17, 2024 at 12:14 PM <devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Date: Sat, 14 Dec 2024 18:01:14 -0500
From: Lucas Oakley <soakley@xxxxxxxxxx>
Subject: [Crash-utility] [PATCH] Fix incorrect 'bt -v' output
suggesting overflow
To: devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Message-ID: <20241214230114.2854910-1-soakley@xxxxxxxxxx>
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 <soakley@xxxxxxxxxx>
---
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:
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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