[PATCH] mm/page_owner: Record timestamp and pid

[Georgi Djakov <georgi.djakov@xxxxxxxxxx>]

From: Liam Mark <lmark@xxxxxxxxxxxxxx>

Collect the time for each allocation recorded in page owner so that
allocation "surges" can be measured.

Record the pid for each allocation recorded in page owner so that
the source of allocation "surges" can be better identified.

Signed-off-by: Liam Mark <lmark@xxxxxxxxxxxxxx>
Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx>
---
 mm/page_owner.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index b735a8eafcdb..e6dc52db5ba5 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -10,6 +10,7 @@
 #include <linux/migrate.h>
 #include <linux/stackdepot.h>
 #include <linux/seq_file.h>
+#include <linux/sched/clock.h>
 
 #include "internal.h"
 
@@ -25,6 +26,8 @@ struct page_owner {
 	gfp_t gfp_mask;
 	depot_stack_handle_t handle;
 	depot_stack_handle_t free_handle;
+	u64 ts_nsec;
+	int pid;
 };
 
 static bool page_owner_enabled = false;
@@ -172,6 +175,8 @@ static inline void __set_page_owner_handle(struct page *page,
 		page_owner->order = order;
 		page_owner->gfp_mask = gfp_mask;
 		page_owner->last_migrate_reason = -1;
+		page_owner->pid = current->pid;
+		page_owner->ts_nsec = local_clock();
 		__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
 		__set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
 
@@ -236,6 +241,8 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage)
 	new_page_owner->last_migrate_reason =
 		old_page_owner->last_migrate_reason;
 	new_page_owner->handle = old_page_owner->handle;
+	new_page_owner->pid = old_page_owner->pid;
+	new_page_owner->ts_nsec = old_page_owner->ts_nsec;
 
 	/*
 	 * We don't clear the bit on the oldpage as it's going to be freed
@@ -349,9 +356,10 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
 		return -ENOMEM;
 
 	ret = snprintf(kbuf, count,
-			"Page allocated via order %u, mask %#x(%pGg)\n",
+			"Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns\n",
 			page_owner->order, page_owner->gfp_mask,
-			&page_owner->gfp_mask);
+			&page_owner->gfp_mask, page_owner->pid,
+			page_owner->ts_nsec);
 
 	if (ret >= count)
 		goto err;