Re: [PATCH 1/2] kselftests: mm: Fix wrong __NR_userfaultfd value

[Shuah Khan]

On 9/16/24 00:32, Muhammad Usama Anjum wrote:
> On 9/12/24 8:44 PM, Shuah Khan wrote:
> > On 9/12/24 04:31, Muhammad Usama Anjum wrote:
> > > The value of __NR_userfaultfd was changed to 282 when
> > > asm-generic/unistd.h was included. It makes the test to fail every time
> > > as the correct number of this syscall on x86_64 is 323. Fix the header
> > > to asm/unistd.h.
> >
> > "please elaborate every time" - I just built on my x86_64 and built
> > just fine.
> The build isn't broken.
>
> > I am not saying this isn't a problem, it is good to
> > understand why and how it is failing before making the change.
> I mean to say that the test is failing at run time because the correct
> userfaultfd syscall isn't being found with __NR_userfaultfd = 282.
> _NR_userfaultfd's value depends on the header. When asm-generic/unistd.h
> is included, its value (282) is wrong. I've tested on x86_64.

Okay - how do you know this is wrong? can you provide more details.

git grep _NR_userfaultfd
include/uapi/asm-generic/unistd.h:#define __NR_userfaultfd 282
include/uapi/asm-generic/unistd.h:__SYSCALL(__NR_userfaultfd, sys_userfaultfd)
tools/include/uapi/asm-generic/unistd.h:#define __NR_userfaultfd 282

> The fix is simple. Add the correct header which has _NR_userfaultfd = 323.

I need more details on this number.

thanks,
-- Shuah