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?