linux-kernel - [PATCH] mm/hmm/test: Fix error handling in dmirror_device

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Message-Id: <20251108115346.6368-1-make24@iscas.ac.cn>
Date: Sat,  8 Nov 2025 19:53:46 +0800
From: Ma Ke <make24@...as.ac.cn>
To: akpm@...ux-foundation.org,
	jgg@...pe.ca,
	leon@...nel.org,
	jhubbard@...dia.com,
	mpenttil@...hat.com
Cc: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Ma Ke <make24@...as.ac.cn>,
	stable@...r.kernel.org
Subject: [PATCH] mm/hmm/test: Fix error handling in dmirror_device_init

dmirror_device_init() calls device_initialize() which sets the device
reference count to 1, but fails to call put_device() when error occurs
after dev_set_name() or cdev_device_add() failures. This results in
memory leaks of struct device objects. Additionally,
dmirror_device_remove() lacks the final put_device() call to properly
release the device reference.

Found by code review.

Cc: stable@...r.kernel.org
Fixes: 6a760f58c792 ("mm/hmm/test: use char dev with struct device to get device node")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
 lib/test_hmm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 83e3d8208a54..5159fc36eea6 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -1458,20 +1458,25 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)
 
 	ret = dev_set_name(&mdevice->device, "hmm_dmirror%u", id);
 	if (ret)
-		return ret;
+		goto put_device;
 
 	ret = cdev_device_add(&mdevice->cdevice, &mdevice->device);
 	if (ret)
-		return ret;
+		goto put_device;
 
 	/* Build a list of free ZONE_DEVICE struct pages */
 	return dmirror_allocate_chunk(mdevice, NULL);
+
+put_device:
+	put_device(&mdevice->device);
+	return ret;
 }
 
 static void dmirror_device_remove(struct dmirror_device *mdevice)
 {
 	dmirror_device_remove_chunks(mdevice);
 	cdev_device_del(&mdevice->cdevice, &mdevice->device);
+	put_device(&mdevice->device);
 }
 
 static int __init hmm_dmirror_init(void)
-- 
2.17.1