On Wed, 26 Aug 2020 05:06:59 +0800 kernel test robot <lkp@xxxxxxxxx> wrote:
> drivers/dax/bus.c:626 alloc_dev_dax_range() error: potential null dereference 'alloc'. (__request_region returns null)
> drivers/dax/bus.c:626 alloc_dev_dax_range() error: we previously assumed 'alloc' could be null (see line 610)
yes, looks fishy:
alloc = __request_region(res, start, size, dev_name(dev), 0);
if (!alloc && !dev_dax->nr_range) {
/*
* If we adjusted an existing @ranges leave it alone,
* but if this was an empty set of ranges nothing else
* will release @ranges, so do it now.
*/
kfree(ranges);
return -ENOMEM;
}
...
.start = alloc->start,
Added by "[PATCH v4 18/23] device-dax: Add dis-contiguous resource
support",
https://lkml.kernel.org/r/159643104304.4062302.16561669534797528660.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> drivers/dax/device.c:111:21: warning: variable 'dax_region' set but not used [-Wunused-but-set-variable]
yup, "device-dax: make align a per-device property" needs
--- a/drivers/dax/device.c~device-dax-make-align-a-per-device-property-fix
+++ a/drivers/dax/device.c
@@ -108,7 +108,6 @@ static vm_fault_t __dev_dax_pmd_fault(st
{
unsigned long pmd_addr = vmf->address & PMD_MASK;
struct device *dev = &dev_dax->dev;
- struct dax_region *dax_region;
phys_addr_t phys;
pgoff_t pgoff;
unsigned int fault_size = PMD_SIZE;
@@ -116,7 +115,6 @@ static vm_fault_t __dev_dax_pmd_fault(st
if (check_vma(dev_dax, vmf->vma, __func__))
return VM_FAULT_SIGBUS;
- dax_region = dev_dax->region;
if (dev_dax->align > PMD_SIZE) {
dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
dev_dax->align, fault_size);
@@ -151,7 +149,6 @@ static vm_fault_t __dev_dax_pud_fault(st
{
unsigned long pud_addr = vmf->address & PUD_MASK;
struct device *dev = &dev_dax->dev;
- struct dax_region *dax_region;
phys_addr_t phys;
pgoff_t pgoff;
unsigned int fault_size = PUD_SIZE;
@@ -160,7 +157,6 @@ static vm_fault_t __dev_dax_pud_fault(st
if (check_vma(dev_dax, vmf->vma, __func__))
return VM_FAULT_SIGBUS;
- dax_region = dev_dax->region;
if (dev_dax->align > PUD_SIZE) {
dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
dev_dax->align, fault_size);
_
