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) <vbabka@xxxxxxxxxx>
Thanks, but please change it to Vlastimil Babka <vbabka@xxxxxxx>
It was some mistake between me and thunderbird that it was sent from @k.o.
Ok, will change it.
Signed-off-by: Kassey Li <quic_yingangl@xxxxxxxxxxx>
---
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)
