linux-kernel - [PATCH v2 1/1] mm: kfence: apply kmemleak_ignore

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Date:   Tue, 28 Jun 2022 19:37:11 +0800
From:   <yee.lee@...iatek.com>
To:     <linux-kernel@...r.kernel.org>
CC:     <catalin.marinas@....com>, Yee Lee <yee.lee@...iatek.com>,
        "Alexander Potapenko" <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        "open list:KFENCE" <kasan-dev@...glegroups.com>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: [PATCH v2 1/1] mm: kfence: apply kmemleak_ignore_phys on early allocated pool

From: Yee Lee <yee.lee@...iatek.com>

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@....com>
Suggested-by: Marco Elver <elver@...gle.com>
Signed-off-by: Yee Lee <yee.lee@...iatek.com>
---
 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