+ mm-hmm-test-fix-error-handling-in-dmirror_device_init.patch added to mm-new branch

+ mm-hmm-test-fix-error-handling-in-dmirror_device_init.patch added to mm-new branch

[Andrew Morton]

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The patch titled
     Subject: mm/hmm/test: fix error handling in dmirror_device_init
has been added to the -mm mm-new branch.  Its filename is
     mm-hmm-test-fix-error-handling-in-dmirror_device_init.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hmm-test-fix-error-handling-in-dmirror_device_init.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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fixup patches in mm-new.

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------------------------------------------------------
From: Ma Ke <make24@iscas.ac.cn>
Subject: mm/hmm/test: fix error handling in dmirror_device_init
Date: Sat, 8 Nov 2025 19:53:46 +0800

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.

Link: https://lkml.kernel.org/r/20251108115346.6368-1-make24@iscas.ac.cn
Fixes: 6a760f58c792 ("mm/hmm/test: use char dev with struct device to get device node")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Cc: Haoxiang Li <make24@iscas.ac.cn>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Mika Penttilä <mpenttil@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/test_hmm.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/lib/test_hmm.c~mm-hmm-test-fix-error-handling-in-dmirror_device_init
+++ a/lib/test_hmm.c
@@ -1740,20 +1740,25 @@ static int dmirror_device_init(struct dm
 
 	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, false);
+
+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)
_

Patches currently in -mm which might be from make24@iscas.ac.cn are

mm-hmm-test-fix-error-handling-in-dmirror_device_init.patch