Re: [RFC PATCH] parisc: Define O_NONBLOCK to become 000200000

[Jeroen Roovers <jer@xs4all.nl>]

On Wed, 21 Oct 2020 08:07:15 +0200
Helge Deller <deller@gmx.de> wrote:

> On 10/20/20 7:21 PM, Jeroen Roovers wrote:
> > On Sat, 29 Aug 2020 14:20:17 +0200
> > Helge Deller <deller@gmx.de> wrote:
> >  
> >> HPUX has separate NDELAY & NONBLOCK values. In the past we wanted
> >> to be able to run HP-UX binaries natively on parisc Linux which is
> >> why we defined O_NONBLOCK to 000200004 to distinguish NDELAY &
> >> NONBLOCK bits.
> >> But with 2 bits set in this bitmask we often ran into compatibility
> >> issues with other Linux applications which often only test one bit
> >> (or even compare the values).
> >>
> >> To avoid such issues in the future, this patch changes O_NONBLOCK
> >> to become 000200000. That way old programs will still be
> >> functional, and for new programs we now have only one bit set.  
> >
> > I am seeing a problem with this exact commit in userland, so I think
> > that last sentence is incorrect:  
> 
> Thanks for testing and bisecting!!!
> 
> I'm fine with reverting the change, but we really need to
> analyze what is broken (and why).
> 
> In general the kernel sources seem ok as it's important,
> that code just check if bits are set, not if the value
> is equal to something e.g.
> good:  if (flags & O_NONBLOCK) { ... }
> bad:   if (flags == O_NONBLOCK) { .... }
> 
> 
> > The first sign (in the boot process) that something is wrong is that
> > idmapd fails to start:
> >
> >  * Starting idmapd ...
> >  * make sure DNOTIFY support is enabled ...
> >  [ !! ]
> >  * ERROR: rpc.idmapd failed to start
> >  * ERROR: cannot start nfsclient as rpc.idmapd would not start  
> 
> Could you try an strace on it?

[after editing the startup script to run `strace -f .. rpc.idmapd`:]

https://rooversj.home.xs4all.nl/rpc.idmapd.strace

> idmapd is from glibc, so I'll look into it too.
> 
> > Then, elogind reports an error when I ssh in as regular user:
> >
> > [  297.825133][ T4273] elogind-daemon[4273]: Failed to register
> > SIGHUP handler: Invalid argument
> > [  297.825133][ T4273] elogind-daemon[4273]: Failed to register
> > SIGHUP handler: Invalid argument [  298.040379][ T4273]
> > elogind-daemon[4273]: Failed to fully start up daemon: Invalid
> > argument [  298.040379][T4273] elogind-daemon[4273]: Failed to
> > fully start up daemon: Invalid argument

strace -f -o /tmp/elogind.strace /lib/elogind/elogind

https://rooversj.home.xs4all.nl/elogind.strace

> >
> > Yet the unprivileged user succeeds in logging in over SSH. Following
> > that, sudo fails:
> >
> > jeroen@karsten ~ $ sudo -i
> > sudo: unable to allocate memory
> >
> > root can still login on the serial console and over SSH.  
> 
> At first thought I assume those issues are not related to the
> O_NONBLOCK patch. Can you try strace on the sudo too ?

strace -f -u jeroen sudo -i
[...]
pipe2(0x42f4712c, O_NONBLOCK|O_CLOEXEC) = -1 EINVAL (Invalid argument)
openat(AT_FDCWD, 0xfadd9b50, O_RDONLY|O_CLOEXEC) = 3
fstat64(3, 0xfadd9e88)                  = 0
read(3, 0x42f47258, 4096)               = 2998
read(3, "", 4096)                       = 0
close(3)                                = 0
openat(AT_FDCWD, 0x42f46bc0, O_RDONLY)  = -1 ENOENT (No such file or
directory) openat(AT_FDCWD, 0x42f46f48, O_RDONLY)  = -1 ENOENT (No such
file or directory) openat(AT_FDCWD, 0x42f46fc8, O_RDONLY)  = -1 ENOENT
(No such file or directory) openat(AT_FDCWD, 0x42f46f78, O_RDONLY)  =
-1 ENOENT (No such file or directory) ioctl(2, TCGETS, 0xfadd9c08)
      = 0 write(2, 0xfadd7f46, 4sudo)                 = 4
ioctl(2, TCGETS, 0xfadd9c08)            = 0
write(2, 0xf8151e94, 2: )                 = 2
ioctl(2, TCGETS, 0xfadd9c08)            = 0
write(2, 0xfadd9608, 25unable to allocate memory)                = 25
ioctl(2, TCGETS, 0xfadd9c08)            = 0
write(2, 0x42e39934, 2
)                 = 2
exit_group(1)                           = ?
+++ exited with 1 +++

https://rooversj.home.xs4all.nl/sudo-i.strace


Regards,
     jer