[Crash-utility] Re: [PATCH] Fix incorrect 'bt -v' output suggesting overflow

Hi, Lucas Thank you for the fix. On Tue, Dec 17, 2024 at 12:14 PM < devel-request(a)lists.crash-utility.osci.io&gt; wrote: > Date: Sat, 14 Dec 2024 18:01:14 -0500 > From: Lucas Oakley <soakley(a)redhat.com&gt; > Subject: [Crash-utility] [PATCH] Fix incorrect 'bt -v' output > suggesting overflow > To: devel(a)lists.crash-utility.osci.io > Message-ID: <20241214230114.2854910-1-soakley(a)redhat.com&gt; > 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(a)redhat.com&gt; > --- > 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 >