----- Original Message -----
> From: "Hugh Dickins" <[email protected]>
> To: "Shaohua Li" <[email protected]>
> Cc: "CAI Qian" <[email protected]>, "linux-mm" <[email protected]>,
> "linux-kernel" <[email protected]>,
> "Rik van Riel" <[email protected]>, "Sasha Levin" <[email protected]>,
> "Andrew Morton"
> <[email protected]>, "Linus Torvalds" <[email protected]>
> Sent: Friday, March 8, 2013 2:49:48 AM
> Subject: Re: change of behavior for madvise in 3.9-rc1
>
> On Thu, 7 Mar 2013, Shaohua Li wrote:
> > On Wed, Mar 06, 2013 at 11:05:04PM -0500, CAI Qian wrote:
> > > Bisecting indicated that this commit,
> > > 1998cc048901109a29924380b8e91bc049b32951
> > > mm: make madvise(MADV_WILLNEED) support swap file prefetch
> > >
> > > Caused an LTP test failure,
> > > http://goo.gl/1FVPy
> > >
> > > madvise02 1 TPASS : failed as expected:
> > > TEST_ERRNO=EINVAL(22): Invalid argument
> > > madvise02 2 TPASS : failed as expected:
> > > TEST_ERRNO=EINVAL(22): Invalid argument
> > > madvise02 3 TPASS : failed as expected:
> > > TEST_ERRNO=EINVAL(22): Invalid argument
> > > madvise02 4 TPASS : failed as expected:
> > > TEST_ERRNO=ENOMEM(12): Cannot allocate memory
> > > madvise02 5 TFAIL : madvise succeeded unexpectedly
> > >
> > > While it passed without the above commit
> > > madvise02 1 TPASS : failed as expected:
> > > TEST_ERRNO=EINVAL(22): Invalid argument
> > > madvise02 2 TPASS : failed as expected:
> > > TEST_ERRNO=EINVAL(22): Invalid argument
> > > madvise02 3 TPASS : failed as expected:
> > > TEST_ERRNO=EINVAL(22): Invalid argument
> > > madvise02 4 TPASS : failed as expected:
> > > TEST_ERRNO=ENOMEM(12): Cannot allocate memory
> > > madvise02 5 TPASS : failed as expected:
> > > TEST_ERRNO=EBADF(9): Bad file descriptor
> >
> > I thought this is expected behavior. madvise(MADV_WILLNEED) to
> > anonymous memory
> > doesn't return -EBADF now, as now we support swap prefretch.
>
> I agree with Shaohua: although the kernel strives for
> back-compatibility
> with userspace, I don't think that goes so far as to tell an
> arbitrary LTP
> test that it has failed, once the kernel has been enhanced to support
> new
> functionality. We could never add or extend system calls if that
> were so.
Thanks for looking this. We will try to fix the LTP test instead.
>
> Hugh
>
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