[PATCH v2 1/1] mm: kfence: apply kmemleak_ignore_phys on early allocated pool

From: yee.lee
Date: Tue Jun 28 2022 - 07:37:52 EST


From: Yee Lee <yee.lee@xxxxxxxxxxxx>

This patch solves two issues.

(1) The pool allocated by memblock needs to unregister from
kmemleak scanning. Apply kmemleak_ignore_phys to replace the
original kmemleak_free as its address now is stored in the phys tree.

(2) The pool late allocated by page-alloc doesn't need to unregister.
Move out the freeing operation from its call path.

Suggested-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Suggested-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Yee Lee <yee.lee@xxxxxxxxxxxx>
---
mm/kfence/core.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 4e7cd4c8e687..32a4a75e820c 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -600,14 +600,6 @@ static unsigned long kfence_init_pool(void)
addr += 2 * PAGE_SIZE;
}

- /*
- * The pool is live and will never be deallocated from this point on.
- * Remove the pool object from the kmemleak object tree, as it would
- * otherwise overlap with allocations returned by kfence_alloc(), which
- * are registered with kmemleak through the slab post-alloc hook.
- */
- kmemleak_free(__kfence_pool);
-
return 0;
}

@@ -620,8 +612,16 @@ static bool __init kfence_init_pool_early(void)

addr = kfence_init_pool();

- if (!addr)
+ if (!addr) {
+ /*
+ * The pool is live and will never be deallocated from this point on.
+ * Ignore the pool object from the kmemleak phys object tree, as it would
+ * otherwise overlap with allocations returned by kfence_alloc(), which
+ * are registered with kmemleak through the slab post-alloc hook.
+ */
+ kmemleak_ignore_phys(__pa(__kfence_pool));
return true;
+ }

/*
* Only release unprotected pages, and do not try to go back and change
--
2.18.0