mm/page_owner: record timestamp and pid

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.

The above is very useful when doing memory analysis.  On a crash for
example, we can get this information from kdump (or ramdump) and parse it
to figure out memory allocation problems.

Please note that on x86_64 this increases the size of struct page_owner
from 16 bytes to 32.

Vlastimil: it's not a functionality intended for production, so unless
somebody says they need to enable page_owner for debugging and this
increase prevents them from fitting into available memory, let's not
complicate things with making this optional.

[lmark@codeaurora.org: v3]
  Link: https://lkml.kernel.org/r/20201210160357.27779-1-georgi.djakov@linaro.org

Link: https://lkml.kernel.org/r/20201209125153.10533-1-georgi.djakov@linaro.org
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/mm/page_owner.c b/mm/page_owner.c
index b735a8eafcdb..af464bb7fbe7 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;
+	pid_t 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;
@@ -427,8 +435,9 @@ void __dump_page_owner(struct page *page)
 	else
 		pr_alert("page_owner tracks the page as freed\n");
 
-	pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
-		 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
+	pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, ts %llu\n",
+		 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
+		 page_owner->pid, page_owner->ts_nsec);
 
 	handle = READ_ONCE(page_owner->handle);
 	if (!handle) {