Commit 8f0efa81 authored by Kassey Li's avatar Kassey Li Committed by Andrew Morton
Browse files

mm/page_owner.c: add llseek for page_owner 

It is too slow to dump all the pages, in some usage we just want to dump a
given start pfn, for example: a CMA range or a single page.

To speed up and save time, this change allows specifying of a start pfn by
adding llseek for page_owner.

Link: https://lkml.kernel.org/r/20220818022425.31056-1-quic_yingangl@quicinc.com


Signed-off-by: default avatarKassey Li <quic_yingangl@quicinc.com>
Suggested-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 72c33ef4

Documentation/mm/page_owner.rst

+5 −0
Original line number Diff line number Diff line
@@ -94,6 +94,11 @@ Usage 
	Page allocated via order XXX, ...

	PFN XXX ...

	// Detailed stack

    By default, it will do full pfn dump, to start with a given pfn,

    page_owner supports fseek.



    FILE *fp = fopen("/sys/kernel/debug/page_owner", "r");

    fseek(fp, pfn_start, SEEK_SET);



   The ``page_owner_sort`` tool ignores ``PFN`` rows, puts the remaining rows

   in buf, uses regexp to extract the page order value, counts the times

mm/page_owner.c

+21 −3
Original line number Diff line number Diff line
@@ -516,8 +516,10 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
		return -EINVAL;



	page = NULL;

	pfn = min_low_pfn + *ppos;



	if (*ppos == 0)

		pfn = min_low_pfn;

	else

		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++;
@@ -588,7 +590,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
			goto ext_put_continue;



		/* Record the next PFN to read in the file offset */

		*ppos = (pfn - min_low_pfn) + 1;

		*ppos = pfn + 1;



		page_owner_tmp = *page_owner;

		page_ext_put(page_ext);
@@ -601,6 +603,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
	return 0;

}



static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)

{

	switch (orig) {

	case SEEK_SET:

		file->f_pos = offset;

		break;

	case SEEK_CUR:

		file->f_pos += offset;

		break;

	default:

		return -EINVAL;

	}

	return file->f_pos;

}



static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)

{

	unsigned long pfn = zone->zone_start_pfn;
@@ -693,6 +710,7 @@ static void init_early_allocated_pages(void) 


static const struct file_operations proc_page_owner_operations = {

	.read		= read_page_owner,

	.llseek		= lseek_page_owner,

};



static int __init pageowner_init(void)