There is usage to dump a given cma region page_owner
instead of all page's.
This change allows to specify a ppos as start_pfn
by fseek.
Any invalid ppos will be skipped, so it did not
broken the origin dump feature.
Suggested-by: Vlastimil Babka (SUSE) <[email protected]>
Signed-off-by: Kassey Li <[email protected]>
---
mm/page_owner.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/mm/page_owner.c b/mm/page_owner.c
index e4c6f3f1695b..231b1877af99 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -497,8 +497,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
return -EINVAL;
page = NULL;
- pfn = min_low_pfn + *ppos;
+ pfn = *ppos;
/* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
pfn++;
@@ -561,7 +561,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
continue;
/* Record the next PFN to read in the file offset */
- *ppos = (pfn - min_low_pfn) + 1;
+ *ppos = pfn + 1;
return print_page_owner(buf, count, pfn, page,
page_owner, handle);
@@ -570,6 +570,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
return 0;
}
+static loff_t llseek_page_owner(struct file *file, loff_t offset, int whence)
+{
+ loff_t retval = 0;
+ switch (whence) {
+ case SEEK_CUR:
+ case SEEK_SET:
+ file->f_pos = offset;
+ break;
+ default:
+ retval = -ENXIO;
+ }
+
+ return retval;
+}
+
static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
{
unsigned long pfn = zone->zone_start_pfn;
@@ -660,6 +675,7 @@ static void init_early_allocated_pages(void)
static const struct file_operations proc_page_owner_operations = {
.read = read_page_owner,
+ .llseek = llseek_page_owner,
};
static int __init pageowner_init(void)
--
2.17.1
On 8/8/22 09:36, Kassey Li wrote:
> There is usage to dump a given cma region page_owner
> instead of all page's.
>
> This change allows to specify a ppos as start_pfn
> by fseek.
>
> Any invalid ppos will be skipped, so it did not
> broken the origin dump feature.
>
> Suggested-by: Vlastimil Babka (SUSE) <[email protected]>
Thanks, but please change it to Vlastimil Babka <[email protected]>
It was some mistake between me and thunderbird that it was sent from @k.o.
> Signed-off-by: Kassey Li <[email protected]>
> ---
> mm/page_owner.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index e4c6f3f1695b..231b1877af99 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -497,8 +497,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
> return -EINVAL;
>
> page = NULL;
> - pfn = min_low_pfn + *ppos;
>
> + pfn = *ppos;
Maybe we could still optimize the typical case a bit such that when it's 0,
we skip to min_low_pfn immediately.
> /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
> while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
> pfn++;
> @@ -561,7 +561,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
> continue;
>
> /* Record the next PFN to read in the file offset */
> - *ppos = (pfn - min_low_pfn) + 1;
> + *ppos = pfn + 1;
>
> return print_page_owner(buf, count, pfn, page,
> page_owner, handle);
> @@ -570,6 +570,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
> return 0;
> }
>
> +static loff_t llseek_page_owner(struct file *file, loff_t offset, int whence)
> +{
> + loff_t retval = 0;
> + switch (whence) {
> + case SEEK_CUR:
It's not correct for SEEK_CUR to behave like this, no?
Can we perhaps reuse the existing mem_lseek() ?
Also we should update Documentation/mm/page_owner.rst to document the lseek
support and that it works with a pfn.
Thanks!
> + case SEEK_SET:
> + file->f_pos = offset;
> + break;
> + default:
> + retval = -ENXIO;
> + }
> +
> + return retval;
> +}
> +
> static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
> {
> unsigned long pfn = zone->zone_start_pfn;
> @@ -660,6 +675,7 @@ static void init_early_allocated_pages(void)
>
> static const struct file_operations proc_page_owner_operations = {
> .read = read_page_owner,
> + .llseek = llseek_page_owner,
> };
>
> static int __init pageowner_init(void)
On 8/8/2022 11:33 PM, Vlastimil Babka (SUSE) wrote:
> On 8/8/22 09:36, Kassey Li wrote:
>> There is usage to dump a given cma region page_owner
>> instead of all page's.
>>
>> This change allows to specify a ppos as start_pfn
>> by fseek.
>>
>> Any invalid ppos will be skipped, so it did not
>> broken the origin dump feature.
>>
>> Suggested-by: Vlastimil Babka (SUSE) <[email protected]>
>
> Thanks, but please change it to Vlastimil Babka <[email protected]>
> It was some mistake between me and thunderbird that it was sent from @k.o.
Ok, will change it.
>
>> Signed-off-by: Kassey Li <[email protected]>
>> ---
>> mm/page_owner.c | 20 ++++++++++++++++++--
>> 1 file changed, 18 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/page_owner.c b/mm/page_owner.c
>> index e4c6f3f1695b..231b1877af99 100644
>> --- a/mm/page_owner.c
>> +++ b/mm/page_owner.c
>> @@ -497,8 +497,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>> return -EINVAL;
>>
>> page = NULL;
>> - pfn = min_low_pfn + *ppos;
>>
>> + pfn = *ppos;
>
> Maybe we could still optimize the typical case a bit such that when it's 0,
> we skip to min_low_pfn immediately.
>
>> /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
>> while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
>> pfn++;
>> @@ -561,7 +561,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>> continue;
>>
>> /* Record the next PFN to read in the file offset */
>> - *ppos = (pfn - min_low_pfn) + 1;
>> + *ppos = pfn + 1;
>>
>> return print_page_owner(buf, count, pfn, page,
>> page_owner, handle);
>> @@ -570,6 +570,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>> return 0;
>> }
>>
>> +static loff_t llseek_page_owner(struct file *file, loff_t offset, int whence)
>> +{
>> + loff_t retval = 0;
>> + switch (whence) {
>> + case SEEK_CUR:
>
> It's not correct for SEEK_CUR to behave like this, no?
> Can we perhaps reuse the existing mem_lseek() ?
agree.
>
> Also we should update Documentation/mm/page_owner.rst to document the lseek
> support and that it works with a pfn.
will do this in v5 patch set.
>
> Thanks!
>
>> + case SEEK_SET:
>> + file->f_pos = offset;
>> + break;
>> + default:
>> + retval = -ENXIO;
>> + }
>> +
>> + return retval;
>> +}
>> +
>> static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
>> {
>> unsigned long pfn = zone->zone_start_pfn;
>> @@ -660,6 +675,7 @@ static void init_early_allocated_pages(void)
>>
>> static const struct file_operations proc_page_owner_operations = {
>> .read = read_page_owner,
>> + .llseek = llseek_page_owner,
>> };
>>
>> static int __init pageowner_init(void)
>