Re: [Linaro-mm-sig] [PATCH 2/6] mm: introduce vma_set_file function v3

Am 09.10.20 um 17:14 schrieb Jason Gunthorpe:

On Fri, Oct 09, 2020 at 05:03:38PM +0200, Christian König wrote:

...

+/*

• • Change backing file, only valid to use during initial VMA setup.
• */

+void vma_set_file(struct vm_area_struct *vma, struct file *file) +{

• if (file)

•        get_file(file);
  

• swap(vma->vm_file, file);
• if (file)

• fput(file);
  

+}

fput crashes when file is NULL so the error handling after unmap_and_free_vma: can't handle this case, similarly vm_file can't be NULL either.

So just simply:

swap(vma->vm_file, file); get_file(vma->vm_file); fput(file); Will do?

I was considering this as well, yes.

Just let it crash if any of them are wrongly NULL.

Mhm, changing from anonymous to file backed or reverse is probably not such a good idea.

So yes catching those problems early is probably the best approach we could do.

Going to do this in v4 if nobody objects.

Regards, Christian.

Jason