linux-kernel - [PATCH v4 13/15] lockdep: Apply lock_acquire(release) on __Set(_

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Date:   Fri,  9 Dec 2016 14:12:09 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     peterz@...radead.org, mingo@...nel.org
Cc:     tglx@...utronix.de, walken@...gle.com, boqun.feng@...il.com,
        kirill@...temov.name, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, iamjoonsoo.kim@....com,
        akpm@...ux-foundation.org, npiggin@...il.com
Subject: [PATCH v4 13/15] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked

Usually PG_locked bit is updated by lock_page() or unlock_page().
However, it can be also updated through __SetPageLocked() or
__ClearPageLockded(). They have to be considered, to get paired between
acquire and release.

Furthermore, e.g. __SetPageLocked() in add_to_page_cache_lru() is called
frequently. We might miss many chances to check deadlock if we ignore it.
Consider __Set(__Clear)PageLockded as well.

Signed-off-by: Byungchul Park <byungchul.park@....com>
---
 include/linux/page-flags.h | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index e5a3244..e28f232 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -249,7 +249,6 @@ static inline int TestClearPage##uname(struct page *page) { return 0; }
 #define TESTSCFLAG_FALSE(uname)						\
 	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 
-__PAGEFLAG(Locked, locked, PF_NO_TAIL)
 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
 PAGEFLAG(Referenced, referenced, PF_HEAD)
 	TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
@@ -351,6 +350,35 @@ TESTCLEARFLAG(Young, young, PF_ANY)
 PAGEFLAG(Idle, idle, PF_ANY)
 #endif
 
+#ifdef CONFIG_LOCKDEP_PAGELOCK
+#include <linux/lockdep.h>
+
+TESTPAGEFLAG(Locked, locked, PF_NO_TAIL)
+
+static __always_inline void __SetPageLocked(struct page *page)
+{
+	__set_bit(PG_locked, &PF_NO_TAIL(page, 1)->flags);
+
+	page = compound_head(page);
+	lock_acquire_exclusive(&page->map, 0, 1, NULL, _RET_IP_);
+}
+
+static __always_inline void __ClearPageLocked(struct page *page)
+{
+	__clear_bit(PG_locked, &PF_NO_TAIL(page, 1)->flags);
+
+	page = compound_head(page);
+	/*
+	 * lock_commit_crosslock() is necessary for crosslock
+	 * when the lock is released, before lock_release().
+	 */
+	lock_commit_crosslock(&page->map);
+	lock_release(&page->map, 0, _RET_IP_);
+}
+#else
+__PAGEFLAG(Locked, locked, PF_NO_TAIL)
+#endif
+
 /*
  * On an anonymous page mapped into a user virtual memory area,
  * page->mapping points to its anon_vma, not to a struct address_space;
-- 
1.9.1