Re: [PATCH RFC 3/2] fstests: check that we can't write to swap files

[Andrew Morton]

On Thu, 15 Aug 2019 09:34:34 -0700 "Darrick J. Wong" <darrick.wong@xxxxxxxxxx> wrote:

> While active, the media backing a swap file is leased to the kernel.
> Userspace has no business writing to it.  Make sure we can't do this.

I don't think this tests the case where a file was already open for
writing and someone does swapon(that file)?

And then does swapoff(that file), when writes should start working again?

Ditto all the above, with s/open/mmap/.


Do we handle (and test!) the case where there's unwritten dirty
pagecache at the time of swapon()?  Ditto pte-dirty MAP_SHARED pages?