loopback mount failing on 2.6.0-test7

loopback mount failing on 2.6.0-test7

[Alex Williamson]

  Looks like some recent changes involving passing more errors up from
get_user_pages is making loopback mounting fail.  I've traced this down
to mount trying to do an mlockall (it probably shouldn't be doing this
for what it's attempting to do).  The test that's failing is:

!(flags & vma->vm_flags)

The values in question are:

flags: 0x1 VM_READ
vm_flags: 0x2070 VM_LOCKED, VM_MAY{READ,WRITE,EXEC}

I tested a 2.4 kernel, and the same test fails, but it's not propagated
out to the system call.  It appears that the failing region is the
"---p" mapping of libc.  x86 has no such mapping.  Is this a broken use
of mlockall, or does the error propagation change make it so mlockall
cannot work on ia64?  Thanks,

	Alex

-- 
Alex Williamson                             HP Linux & Open Source Lab

Re: loopback mount failing on 2.6.0-test7

[David Mosberger]

>>>>> On Fri, 17 Oct 2003 10:56:44 -0600, Alex Williamson <alex.williamson@hp.com> said:

  Alex> Looks like some recent changes involving passing more errors up from
  Alex> get_user_pages is making loopback mounting fail.  I've traced this down
  Alex> to mount trying to do an mlockall (it probably shouldn't be doing this
  Alex> for what it's attempting to do).  The test that's failing is:

  Alex> !(flags & vma->vm_flags)

  Alex> The values in question are:

  Alex> flags: 0x1 VM_READ
  Alex> vm_flags: 0x2070 VM_LOCKED, VM_MAY{READ,WRITE,EXEC}

  Alex> I tested a 2.4 kernel, and the same test fails, but it's not propagated
  Alex> out to the system call.  It appears that the failing region is the
  Alex> "---p" mapping of libc.  x86 has no such mapping.  Is this a broken use
  Alex> of mlockall, or does the error propagation change make it so mlockall
  Alex> cannot work on ia64?  Thanks,

Andi Kleen hacked some stuff in this area recently.  I didn't follow
the discussion too closely, but he complained that mlockall() failed
for "no-access" mappings.  I thought the fix went into test7 already,
but I may be misremembering and perhaps it's only in the current bk
tree.  Could you check Linus' bk tree and see if it fixes the problem?

	--david

Re: loopback mount failing on 2.6.0-test7

[Alex Williamson]

On Fri, 2003-10-17 at 11:21, David Mosberger wrote:

> Andi Kleen hacked some stuff in this area recently.  I didn't follow
> the discussion too closely, but he complained that mlockall() failed
> for "no-access" mappings.  I thought the fix went into test7 already,
> but I may be misremembering and perhaps it's only in the current bk
> tree.  Could you check Linus' bk tree and see if it fixes the problem?
> 

   Sure enough, seems to be fixed in Linus' bk.  It was still broken in
linux-ia64-2.5 as of yesterday though.  Thanks,

	Alex

-- 
Alex Williamson                             HP Linux & Open Source Lab

Re: loopback mount failing on 2.6.0-test7

[David Mosberger]

>>>>> On Fri, 17 Oct 2003 13:10:43 -0600, Alex Williamson <alex.williamson@hp.com> said:

  Alex>    Sure enough, seems to be fixed in Linus' bk.  It was still
  Alex> broken in linux-ia64-2.5 as of yesterday though.

Yes, my tree is strictly 2.6.0-test7+ia64 fixes, at the moment.

	--david