linux-kernel - [RFC][PATCH] mm/page_isolation: tracing: trace all test_pages

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Date:   Mon, 23 Aug 2021 16:28:23 -0400
From:   "George G. Davis" <george_davis@...tor.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>
CC:     <george_davis@...tor.com>, Eugeniu Rosca <erosca@...adit-jv.com>,
        "George G. Davis" <davis.george@...mens.com>
Subject: [RFC][PATCH] mm/page_isolation: tracing: trace all test_pages_isolated failures

From: "George G. Davis" <davis.george@...mens.com>

Some test_pages_isolated failure conditions don't include trace points.
For debugging issues caused by "pinned" pages, make sure to trace all
calls whether they succeed or fail. In this case, a failure case did not
result in a trace point. So add the missing failure case in
test_pages_isolated traces.

Signed-off-by: George G. Davis <davis.george@...mens.com>
---
 mm/page_isolation.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index bddf788f45bf..fff55bb830f9 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -287,6 +287,7 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 	unsigned long pfn, flags;
 	struct page *page;
 	struct zone *zone;
+	int ret;
 
 	/*
 	 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
@@ -299,15 +300,21 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 			break;
 	}
 	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
-	if ((pfn < end_pfn) || !page)
-		return -EBUSY;
+	if ((pfn < end_pfn) || !page) {
+		ret = -EBUSY;
+		goto out;
+	}
+
 	/* Check all pages are free or marked as ISOLATED */
 	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
 	pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags);
 	spin_unlock_irqrestore(&zone->lock, flags);
 
+	ret = pfn < end_pfn ? -EBUSY : 0;
+
+out:
 	trace_test_pages_isolated(start_pfn, end_pfn, pfn);
 
-	return pfn < end_pfn ? -EBUSY : 0;
+	return ret;
 }
-- 
2.17.1