mm: make generic arch_is_kernel_initmem_freed() do what it says

Commit 7a5da02de8d6 ("locking/lockdep: check for freed initmem in
static_obj()") added arch_is_kernel_initmem_freed() which is supposed to
report whether an object is part of already freed init memory.

For the time being, the generic version of
arch_is_kernel_initmem_freed() always reports 'false', allthough
free_initmem() is generically called on all architectures.

Therefore, change the generic version of arch_is_kernel_initmem_freed()
to check whether free_initmem() has been called.  If so, then check if a
given address falls into init memory.

To ease the use of system_state, move it out of line into its only
caller which is lockdep.c

Link: https://lkml.kernel.org/r/1d40783e676e07858be97d881f449ee7ea8adfb1.1633001016.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index bf1c00c881e4..8e118caf835e 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -788,6 +788,21 @@ static int very_verbose(struct lock_class *class)
  * Is this the address of a static object:
  */
 #ifdef __KERNEL__
+/*
+ * Check if an address is part of freed initmem. After initmem is freed,
+ * memory can be allocated from it, and such allocations would then have
+ * addresses within the range [_stext, _end].
+ */
+#ifndef arch_is_kernel_initmem_freed
+static int arch_is_kernel_initmem_freed(unsigned long addr)
+{
+	if (system_state < SYSTEM_FREEING_INITMEM)
+		return 0;
+
+	return init_section_contains((void *)addr, 1);
+}
+#endif
+
 static int static_obj(const void *obj)
 {
 	unsigned long start = (unsigned long) &_stext,