linux-kernel - [PATCH 1/2] mm/kmemleak: Compact kmemleak

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Message-Id: <20240307190548.963626-2-longman@redhat.com>
Date: Thu,  7 Mar 2024 14:05:47 -0500
From: Waiman Long <longman@...hat.com>
To: Catalin Marinas <catalin.marinas@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Waiman Long <longman@...hat.com>
Subject: [PATCH 1/2] mm/kmemleak: Compact kmemleak_object further

With commit 56a61617dd22 ("mm: use stack_depot for recording kmemleak's
backtrace"), the size of kmemleak_object has been reduced by 128 bytes
for 64-bit arches. The replacement "depot_stack_handle_t trace_handle"
is actually just 4 bytes long leaving a hole of 4 bytes. By moving up
trace_handle to another existing 4-byte hold, we can save 8 more bytes
from kmemleak_object reducing its overall size from 248 to 240 bytes.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 mm/kmemleak.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 4f58f6170cdf..0114a694e520 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -158,9 +158,9 @@ struct kmemleak_object {
 	int count;
 	/* checksum for detecting modified objects */
 	u32 checksum;
+	depot_stack_handle_t trace_handle;
 	/* memory ranges to be scanned inside an object (empty for all) */
 	struct hlist_head area_list;
-	depot_stack_handle_t trace_handle;
 	unsigned long jiffies;		/* creation timestamp */
 	pid_t pid;			/* pid of the current task */
 	char comm[TASK_COMM_LEN];	/* executable name */
-- 
2.39.3