linux-kernel - [PATCH 4/5] Capture references to page cache pages

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Date:	Tue,  5 Jul 2011 13:52:38 +0530
From:	Ankita Garg <ankita@...ibm.com>
To:	linux-mm@...ck.org
Cc:	ankita@...ibm.com, svaidy@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] Capture references to page cache pages

Hi,

Page cache accesses may not be mapped, hence fake an access when a
pagecache page is looked up, by marking the corresponding memory
address block as accessed.

Signed-off-by: Ankita Garg <ankita@...ibm.com>
---
 mm/filemap.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index a8251a8..7ae7f36 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -36,6 +36,7 @@
 #include <linux/mm_inline.h> /* for page_is_file_cache() */
 #include <linux/cleancache.h>
 #include "internal.h"
+#include <linux/memtrace.h>
 
 /*
  * FIXME: remove all knowledge of the buffer layer from the core VM
@@ -730,6 +731,13 @@ repeat:
 			page_cache_release(page);
 			goto repeat;
 		}
+#if defined(CONFIG_MEMTRACE)
+		if(get_pg_trace_pid() != -1 && current->mem_trace) {
+			unsigned long pfn = page_to_pfn(page);
+			if(pfn_valid(pfn))
+				mark_memtrace_block_accessed(pfn << PAGE_SHIFT);
+		}
+#endif
 	}
 out:
 	rcu_read_unlock();
-- 
1.7.4

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