linux-kernel - Re: [PATCH 4/5] vfio: Introduce vfio_device_ops.get_unmapped

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Message-ID: <aFGMG3763eSv9l8b@x1.local>
Date: Tue, 17 Jun 2025 11:39:07 -0400
From: Peter Xu <peterx@...hat.com>
To: kernel test robot <lkp@...el.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, kvm@...r.kernel.org,
	oe-kbuild-all@...ts.linux.dev,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	Zi Yan <ziy@...dia.com>, Jason Gunthorpe <jgg@...dia.com>,
	Alex Mastro <amastro@...com>, David Hildenbrand <david@...hat.com>,
	Nico Pache <npache@...hat.com>
Subject: Re: [PATCH 4/5] vfio: Introduce vfio_device_ops.get_unmapped_area
 hook

On Sat, Jun 14, 2025 at 10:46:45PM +0800, kernel test robot wrote:
> Hi Peter,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Peter-Xu/mm-Deduplicate-mm_get_unmapped_area/20250613-214307
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link:    https://lore.kernel.org/r/20250613134111.469884-5-peterx%40redhat.com
> patch subject: [PATCH 4/5] vfio: Introduce vfio_device_ops.get_unmapped_area hook
> config: sh-randconfig-002-20250614 (https://download.01.org/0day-ci/archive/20250614/202506142215.koMEU2rT-lkp@intel.com/config)
> compiler: sh4-linux-gcc (GCC) 12.4.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250614/202506142215.koMEU2rT-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202506142215.koMEU2rT-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    drivers/vfio/vfio_main.c: In function 'vfio_device_get_unmapped_area':
> >> drivers/vfio/vfio_main.c:1367:24: error: implicit declaration of function 'mm_get_unmapped_area'; did you mean 'get_unmapped_area'? [-Werror=implicit-function-declaration]
>     1367 |                 return mm_get_unmapped_area(current->mm, file, addr,
>          |                        ^~~~~~~~~~~~~~~~~~~~
>          |                        get_unmapped_area
>    cc1: some warnings being treated as errors
> 
> 
> vim +1367 drivers/vfio/vfio_main.c
> 
>   1356	
>   1357	static unsigned long vfio_device_get_unmapped_area(struct file *file,
>   1358							   unsigned long addr,
>   1359							   unsigned long len,
>   1360							   unsigned long pgoff,
>   1361							   unsigned long flags)
>   1362	{
>   1363		struct vfio_device_file *df = file->private_data;
>   1364		struct vfio_device *device = df->device;
>   1365	
>   1366		if (!device->ops->get_unmapped_area)
> > 1367			return mm_get_unmapped_area(current->mm, file, addr,
>   1368						    len, pgoff, flags);
>   1369	
>   1370		return device->ops->get_unmapped_area(device, file, addr, len,
>   1371						      pgoff, flags);
>   1372	}
>   1373	

This is "ARCH_SH + VFIO + !MMU".. I'll make sure to cover this config when
repost.  I'll squash below into the patch:

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 19db8e58d223..cc14884d282f 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1354,6 +1354,7 @@ static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
        return device->ops->mmap(device, vma);
 }
 
+#ifdef CONFIG_ARCH_SUPPORTS_HUGE_PFNMAP
 static unsigned long vfio_device_get_unmapped_area(struct file *file,
                                                   unsigned long addr,
                                                   unsigned long len,
@@ -1370,6 +1371,7 @@ static unsigned long vfio_device_get_unmapped_area(struct file *file,
        return device->ops->get_unmapped_area(device, file, addr, len,
                                              pgoff, flags);
 }
+#endif
 
 const struct file_operations vfio_device_fops = {
        .owner          = THIS_MODULE,
@@ -1380,7 +1382,9 @@ const struct file_operations vfio_device_fops = {
        .unlocked_ioctl = vfio_device_fops_unl_ioctl,
        .compat_ioctl   = compat_ptr_ioctl,
        .mmap           = vfio_device_fops_mmap,
+#ifdef CONFIG_ARCH_SUPPORTS_HUGE_PFNMAP
        .get_unmapped_area = vfio_device_get_unmapped_area,
+#endif
 };
 
 static struct vfio_device *vfio_device_from_file(struct file *file)

-- 
Peter Xu