Re: [PATCH 2/3] vmsplice: make vmsplice a trivial wrapper for preadv2/pwritev2

Linus Torvalds <[email protected]> Fri, 5 Jun 2026 09:02:52 -0700

Newsgroups	org.kernel.vger.linux-api,dev.linux.lists.patches,it.linux.lists.ltp,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kernel.vger.netdev,org.kvack.linux-mm
Message-ID	<CAHk-=wjBZAzPdZgEeHAtSiwJpomt8ZZgKbixuiHfRm09a4=PtA@mail.gmail.com>

On Fri, 5 Jun 2026 at 04:02, Mark Brown <[email protected]> wrote:
>
> FWIW this is triggering a failure in the LTP vmsplice01 test case (which
> sends with a vmsplice() and then tries to read that with a splice()) in
> -next:
>
> | tst_tmpdir.c:316: TINFO: Using /tmp/LTP_vmsp3vEmQ as tmpdir (tmpfs filesystem)
> | L4471tst_test.c:2047: TINFO: LTP version: 20260130
> | L4472tst_test.c:2050: TINFO: Tested kernel: 7.1.0-rc6-next-20260604 #1 SMP @1780589917 armv7l
> | L4473tst_kconfig.c:71: TINFO: Couldn't locate kernel config!
> | L4474tst_test.c:1875: TINFO: Overall timeout per run is 0h 00m 30s

I htink this is the same thing that Christian already noted (he said
"reported by David", but I don't know which David ;), where the
vmsplice() writev() emulation was done as a blocking write, even
though vmsplice only blocked at the beginning (ie waiting only for
_initial_ space to write, not then blocking afterwards).

                 Linus