Commit 6419265899d9 ("sched/fair: Fix division by zero
sysctl_numa_balancing_scan_size") prevented a divide by zero by using
sysctl mechanisms to return EINVAL for a sysctl_numa_balancing_scan_size
value of zero. When moved from a sysctl to a debugfs file, this checking
was lost.
This patch puts zero checking back in place.
Signed-off-by: Chris Hyser <[email protected]>
---
kernel/sched/debug.c | 52 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 51 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 1637b65ba07a..b5fc7e250128 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -278,6 +278,56 @@ static const struct file_operations sched_dynamic_fops = {
#endif /* CONFIG_PREEMPT_DYNAMIC */
+#ifdef CONFIG_NUMA_BALANCING
+
+static ssize_t sched_numa_scan_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ int err;
+ char buf[16];
+ unsigned int scan_size;
+
+ if (cnt > 15)
+ cnt = 15;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+ buf[cnt] = '\0';
+
+ err = kstrtouint(buf, 10, &scan_size);
+ if (err)
+ return err;
+
+ if (!scan_size)
+ return -EINVAL;
+
+ sysctl_numa_balancing_scan_size = scan_size;
+
+ *ppos += cnt;
+ return cnt;
+}
+
+static int sched_numa_scan_show(struct seq_file *m, void *v)
+{
+ seq_printf(m, "%d\n", sysctl_numa_balancing_scan_size);
+ return 0;
+}
+
+static int sched_numa_scan_open(struct inode *inode, struct file *filp)
+{
+ return single_open(filp, sched_numa_scan_show, NULL);
+}
+
+static const struct file_operations sched_numa_scan_fops = {
+ .open = sched_numa_scan_open,
+ .write = sched_numa_scan_write,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+#endif /* CONFIG_NUMA_BALANCING */
+
__read_mostly bool sched_debug_verbose;
static const struct seq_operations sched_debug_sops;
@@ -332,7 +382,7 @@ static __init int sched_init_debug(void)
debugfs_create_u32("scan_delay_ms", 0644, numa, &sysctl_numa_balancing_scan_delay);
debugfs_create_u32("scan_period_min_ms", 0644, numa, &sysctl_numa_balancing_scan_period_min);
debugfs_create_u32("scan_period_max_ms", 0644, numa, &sysctl_numa_balancing_scan_period_max);
- debugfs_create_u32("scan_size_mb", 0644, numa, &sysctl_numa_balancing_scan_size);
+ debugfs_create_file("scan_size_mb", 0644, numa, NULL, &sched_numa_scan_fops);
debugfs_create_u32("hot_threshold_ms", 0644, numa, &sysctl_numa_balancing_hot_threshold);
#endif
--
2.31.1
On 2023-03-30 at 11:07:57 -0400, chris hyser wrote:
> Commit 6419265899d9 ("sched/fair: Fix division by zero
> sysctl_numa_balancing_scan_size") prevented a divide by zero by using
> sysctl mechanisms to return EINVAL for a sysctl_numa_balancing_scan_size
> value of zero. When moved from a sysctl to a debugfs file, this checking
> was lost.
>
> This patch puts zero checking back in place.
>
> Signed-off-by: Chris Hyser <[email protected]>
> ---
> kernel/sched/debug.c | 52 +++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index 1637b65ba07a..b5fc7e250128 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -278,6 +278,56 @@ static const struct file_operations sched_dynamic_fops = {
>
> #endif /* CONFIG_PREEMPT_DYNAMIC */
>
> +#ifdef CONFIG_NUMA_BALANCING
> +
> +static ssize_t sched_numa_scan_write(struct file *filp, const char __user *ubuf,
> + size_t cnt, loff_t *ppos)
> +{
> + int err;
> + char buf[16];
> + unsigned int scan_size;
> +
> + if (cnt > 15)
> + cnt = 15;
> +
> + if (copy_from_user(&buf, ubuf, cnt))
> + return -EFAULT;
> + buf[cnt] = '\0';
> +
> + err = kstrtouint(buf, 10, &scan_size);
While testing the code, it is found that there is a
kstrtouint_from_user() could do the above. Not sure
if it is worthy to use that?
thanks,
Chenyu
On 4/4/23 11:32, Chen Yu wrote:
> On 2023-03-30 at 11:07:57 -0400, chris hyser wrote:
>> Commit 6419265899d9 ("sched/fair: Fix division by zero
>> sysctl_numa_balancing_scan_size") prevented a divide by zero by using
>> sysctl mechanisms to return EINVAL for a sysctl_numa_balancing_scan_size
>> value of zero. When moved from a sysctl to a debugfs file, this checking
>> was lost.
>>
>> This patch puts zero checking back in place.
>>
>> Signed-off-by: Chris Hyser <[email protected]>
>> ---
>> kernel/sched/debug.c | 52 +++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 51 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
>> index 1637b65ba07a..b5fc7e250128 100644
>> --- a/kernel/sched/debug.c
>> +++ b/kernel/sched/debug.c
>> @@ -278,6 +278,56 @@ static const struct file_operations sched_dynamic_fops = {
>>
>> #endif /* CONFIG_PREEMPT_DYNAMIC */
>>
>> +#ifdef CONFIG_NUMA_BALANCING
>> +
>> +static ssize_t sched_numa_scan_write(struct file *filp, const char __user *ubuf,
>> + size_t cnt, loff_t *ppos)
>> +{
>> + int err;
>> + char buf[16];
>> + unsigned int scan_size;
>> +
>> + if (cnt > 15)
>> + cnt = 15;
>> +
>> + if (copy_from_user(&buf, ubuf, cnt))
>> + return -EFAULT;
>> + buf[cnt] = '\0';
>> +
>> + err = kstrtouint(buf, 10, &scan_size);
> While testing the code, it is found that there is a
> kstrtouint_from_user() could do the above. Not sure
> if it is worthy to use that?
Let me look at that. I think in general, replacing a block of code in a
non-perf path with an existing function is better.
And thank you for looking at this.
-chrish
On 4/4/23 11:32, Chen Yu wrote:
> On 2023-03-30 at 11:07:57 -0400, chris hyser wrote:
>> Commit 6419265899d9 ("sched/fair: Fix division by zero
>> sysctl_numa_balancing_scan_size") prevented a divide by zero by using
>> sysctl mechanisms to return EINVAL for a sysctl_numa_balancing_scan_size
>> value of zero. When moved from a sysctl to a debugfs file, this checking
>> was lost.
>>
>> This patch puts zero checking back in place.
>>
>> Signed-off-by: Chris Hyser <[email protected]>
>> ---
>> kernel/sched/debug.c | 52 +++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 51 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
>> index 1637b65ba07a..b5fc7e250128 100644
>> --- a/kernel/sched/debug.c
>> +++ b/kernel/sched/debug.c
>> @@ -278,6 +278,56 @@ static const struct file_operations sched_dynamic_fops = {
>>
>> #endif /* CONFIG_PREEMPT_DYNAMIC */
>>
>> +#ifdef CONFIG_NUMA_BALANCING
>> +
>> +static ssize_t sched_numa_scan_write(struct file *filp, const char __user *ubuf,
>> + size_t cnt, loff_t *ppos)
>> +{
>> + int err;
>> + char buf[16];
>> + unsigned int scan_size;
>> +
>> + if (cnt > 15)
>> + cnt = 15;
>> +
>> + if (copy_from_user(&buf, ubuf, cnt))
>> + return -EFAULT;
>> + buf[cnt] = '\0';
>> +
>> + err = kstrtouint(buf, 10, &scan_size);
> While testing the code, it is found that there is a
> kstrtouint_from_user() could do the above. Not sure
> if it is worthy to use that?
Yes, putting this in results in cleaner code. Thanks.
I just sent a v3 with this change.
-chrish
>
> thanks,
> Chenyu