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From: Andrew Morton <akpm@linux-foundation.org>
To: kernel test robot <lkp@intel.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
	Joao Martins <joao.m.martins@oracle.com>,
	Vishal L Verma <vishal.l.verma@intel.com>,
	Dan Williams <dan.j.williams@intel.com>
Subject: Re: [linux-next:master] BUILD REGRESSION 3a00d3dfd4b68b208ecd5405e676d06c8ad6bb63
Date: Tue, 25 Aug 2020 14:32:18 -0700	[thread overview]
Message-ID: <20200825143218.7fc406bf642ad7f0cc9cfb26@linux-foundation.org> (raw)
In-Reply-To: <5f457d73.gsRq3vmXOfOBWd0d%lkp@intel.com>

On Wed, 26 Aug 2020 05:06:59 +0800 kernel test robot <lkp@intel.com> 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@dwillia2-desk3.amr.corp.intel.com


> 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);
_



  reply	other threads:[~2020-08-25 21:32 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-25 21:06 kernel test robot
2020-08-25 21:32 ` Andrew Morton [this message]
2020-08-26 16:13   ` Joao Martins
2020-08-26 18:32     ` Andrew Morton
2020-08-26 19:45       ` Joao Martins

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