From 4fc089235378d1f9ddb6bcbe67c192ffdcaae0ed Mon Sep 17 00:00:00 2001 From: Stanislav Kinsburskii Date: Mon, 29 Jun 2026 16:30:14 -0700 Subject: [PATCH] lib: test_hmm: use device devt for coherent device range selection Commit af69016dab96 ("lib: test_hmm: implement a device release method") moved the initial dmirror_allocate_chunk() call before cdev_device_add(). That means the struct cdev has not been added yet, so cdev_add() has not initialized mdevice->cdevice.dev. The coherent-device range selection uses the device minor to choose between spm_addr_dev0 and spm_addr_dev1. Reading MINOR(mdevice->cdevice.dev) before cdev_add() therefore always sees an uninitialized dev_t. As a result, both coherent devices select the same physical range, and adding the second device fails due to the overlapping dev_pagemap range. Use mdevice->device.devt instead. It is initialized in dmirror_device_init() before dmirror_allocate_chunk() is called and is the same dev_t later passed to cdev_device_add(). Link: https://lore.kernel.org/178277581197.172200.16265155329935822153.stgit@skinsburskii Fixes: af69016dab96 ("lib: test_hmm: implement a device release method") Signed-off-by: Stanislav Kinsburskii Reviewed-by: Alistair Popple Cc: Balbir Singh Cc: Zenghui Yu (Huawei) Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Signed-off-by: Andrew Morton --- lib/test_hmm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 9c59d1ceb5b5..c4adbf98fac7 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -581,7 +581,7 @@ static int dmirror_allocate_chunk(struct dmirror_device *mdevice, devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; break; case HMM_DMIRROR_MEMORY_DEVICE_COHERENT: - devmem->pagemap.range.start = (MINOR(mdevice->cdevice.dev) - 2) ? + devmem->pagemap.range.start = (MINOR(mdevice->device.devt) - 2) ? spm_addr_dev0 : spm_addr_dev1; devmem->pagemap.range.end = devmem->pagemap.range.start +