Re: [PATCH v2 8/9] selftests/mm: Skip map_populate on weird filesystems

On Fri, 21 Feb 2025 at 19:26, Brendan Jackman jackmanb@google.com wrote:

It seems that 9pfs does not allow truncating unlinked files, Mark Brown has noted that NFS may also behave this way.

I have not investigated at all but I _think_ over the weekend I saw ftruncate() failure on a QEMU guest where /tmp was tmpfs.

Most likely explanation is user probably error (like /tmp wasn't actually tmpfs or the tmpfile() did not actually come from /tmp). But still, maybe just waving my hands and going "buggy filesystem, ignore" wasn't so smart. I should actually understand the problem before switching off tests.

So, I think this and the other "ignore on weird filesystem" patch 9/9 should be ignored for the moment.