[PATCH v2 2/4] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked

[Byungchul Park]

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.
Make __Set(__Clear)PageLockded considered as well.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
---
 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 584b14c..108d2dd 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -262,7 +262,6 @@ static __always_inline int PageCompound(struct page *page)
 #define TESTSCFLAG_FALSE(uname)						\
 	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 
-__PAGEFLAG(Locked, locked, PF_NO_TAIL)
 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
 PAGEFLAG(Referenced, referenced, PF_HEAD)
@@ -374,6 +373,35 @@ static __always_inline int PageSwapCache(struct page *page)
 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((struct lockdep_map *)&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((struct lockdep_map *)&page->map);
+	lock_release((struct lockdep_map *)&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