[PATCH 1/2] mm: mmap: fix fput in error path v2

[Andrew Morton]

On Fri,  6 Nov 2020 12:48:05 +0100 "Christian König" <ckoenig.leichtzumerken at gmail.com> wrote:

> Patch "495c10cc1c0c CHROMIUM: dma-buf: restore args..."
> adds a workaround for a bug in mmap_region.
> 
> As the comment states ->mmap() callback can change
> vma->vm_file and so we might call fput() on the wrong file.
> 
> Revert the workaround and proper fix this in mmap_region.
> 

Seems correct, best I can tell.  Presumably all ->mmap() instances will
correctly fput() to original file* if they're rewriting vma->vm_file.