linux-kernel - Re: [PATCH 1/2] mm: mmap: fix fput in error path v2

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Message-Id: <20201106144811.cf228ca9278ec78887d42960@linux-foundation.org>
Date:   Fri, 6 Nov 2020 14:48:11 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     =?ISO-8859-1?Q? "Christian_K=F6nig" ?= 
        <ckoenig.leichtzumerken@...il.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: mmap: fix fput in error path v2

On Fri,  6 Nov 2020 12:48:05 +0100 "Christian König" <ckoenig.leichtzumerken@...il.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.