Errno for munlock(2) on unlocked mapping ?

[Nicolas Joly <njoly%pasteur.fr@localhost>]

Hi,

While checking some compat linux stuff, i exercized native munlock(2)
behavior ... And noted a small issue with returned errno with unlocked
mapping.

The man page states that it should fail with ENOMEM :

     [ENOMEM]           Some portion of the indicated address range is not
     			allocated.  Some portion of the indicated address
			range is not locked.

But code disagree as EINVAL is returned (from uvm_map_pageable()) for
the attached testcase :

 10066      1 munlock  CALL  mmap(0,0x1000,7,0x1002,0xffffffff,0,0)
 10066      1 munlock  RET   mmap 140187598286848/0x7f7ff7ff7000
 10066      1 munlock  CALL  munlock(0x7f7ff7ff7000,0x1000)
 10066      1 munlock  RET   munlock -1 errno 22 Invalid argument
 10066      1 munlock  CALL  munmap(0x7f7ff7ff7000,0x1000)
 10066      1 munlock  RET   munmap 0

Digging into history, this small behaviour change was introduced in
2001 (sys_mmap.c rev 1.50) with KERN_* error codes removal.

@@ -988,7 +947,7 @@ sys_munlock(p, v, retval)

        error = uvm_map_pageable(&p->p_vmspace->vm_map, addr, addr+size, TRUE,
	    0);
-       return (error == KERN_SUCCESS ? 0 : ENOMEM);
+       return error;
 }

Not sure who's right there ... EINVAL or ENOMEM ?

Thanks.

-- 
Nicolas Joly

Biology IT Center
Institut Pasteur, Paris.

#include <sys/mman.h>

#include <assert.h>
#include <errno.h>
#include <unistd.h>

#define PROT_ALL (PROT_WRITE|PROT_READ|PROT_EXEC)

int main() {
  void *adr;
  size_t len;

  len = getpagesize();

  adr = mmap(NULL, len, PROT_ALL, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
  assert(adr != MAP_FAILED);
  munlock(adr, len);
  assert(munmap(adr, len) != -1);

  return 0; }