Re: parisc: flush pages through tmpalias space

[John David Anglin <dave@xxxxxxxxxxxxxxxxxx>]

On Wed, 29 Dec 2010, James Bottomley wrote:

> > Dec 26 12:30:57 mx3210 kernel: INEQUIVALENT ALIASES 0x402a7000 and 0x402a6000 in file libc-2.11.2.so
> > 
> > This is with 2.6.36.2 and your two patches on a SMP kernel.  I've also seen
> > these messages with a similar UP build in the gcc guality tests.  These
> > check debug info with gdb.
> 
> Yes, I still don't know why, but fortunately the one above is the same
> one I see, which only occurs when the system goes down.  I suspect
> something is specifying a fixed offset for the library mappings which
> violates our 4MB equivalency rule.

Attached is an application that triggers similar errors:

Dec 29 23:27:02 mx3210 kernel: INEQUIVALENT ALIASES 0x11000 and 0x12000 in file example.exe

If I was to guess, I think the problem is likely caused by the brk system
calls from popen:

...
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40001000
mprotect(0x40518000, 1413120, PROT_READ|PROT_WRITE) = 0
mmap(NULL, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40002000
mprotect(0x40518000, 1413120, PROT_READ|PROT_EXEC) = 0
munmap(0x40185000, 24154)               = 0
brk(0)                                  = 0x13000
brk(0x34000)                            = 0x34000
pipe2([3, 4], O_CLOEXEC)                = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x40000a68) = 3035
close(3)                                = 0
...

It's hard to debug because gdb needs to attach.

Dave
-- 
J. David Anglin                                  dave.anglin@xxxxxxxxxxxxxx
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)

/* { dg-do run { xfail *-*-* } } */
/* { dg-options "-g" } */

#define GUALITY_DONT_FORCE_LIVE_AFTER -1

#ifndef STATIC_INLINE
#define STATIC_INLINE /*static*/
#endif

#include "guality.h"

#include <assert.h>

/* Test the debug info for the functions used in the VTA
   presentation at the GCC Summit 2008.  */

typedef struct list {
  struct list *n;
  int v;
} elt, *node;

STATIC_INLINE node
find_val (node c, int v, node e)
{
  while (c < e)
    {
      GUALCHK (c);
      GUALCHK (v);
      GUALCHK (e);
      if (c->v == v)
	return c;
      GUALCHK (c);
      GUALCHK (v);
      GUALCHK (e);
      c++;
    }
  return NULL;
}

STATIC_INLINE node
find_prev (node c, node w)
{
  while (c)
    {
      node o = c;
      c = c->n;
      GUALCHK (c);
      GUALCHK (o);
      GUALCHK (w);
      if (c == w)
	return o;
      GUALCHK (c);
      GUALCHK (o);
      GUALCHK (w);
    }
  return NULL;
}

STATIC_INLINE node
check_arr (node c, node e)
{
  if (c == e)
    return NULL;
  e--;
  while (c < e)
    {
      GUALCHK (c);
      GUALCHK (e);
      if (c->v > (c+1)->v)
	return c;
      GUALCHK (c);
      GUALCHK (e);
      c++;
    }
  return NULL;
}

STATIC_INLINE node
check_list (node c, node t)
{
  while (c != t)
    {
      node n = c->n;
      GUALCHK (c);
      GUALCHK (n);
      GUALCHK (t);
      if (c->v > n->v)
	return c;
      GUALCHK (c);
      GUALCHK (n);
      GUALCHK (t);
      c = n;
    }
  return NULL;
}

struct list testme[] = {
  { &testme[1],  2 },
  { &testme[2],  3 },
  { &testme[3],  5 },
  { &testme[4],  7 },
  { &testme[5], 11 },
  { NULL, 13 },
};

int
main (int argc, char *argv[])
{
  int n = sizeof (testme) / sizeof (*testme);
  node first, last, begin, end, ret;

  GUALCHKXPR (n);

  begin = first = &testme[0];
  last = &testme[n-1];
  end = &testme[n];

  GUALCHKXPR (first);
  GUALCHKXPR (last);
  GUALCHKXPR (begin);
  GUALCHKXPR (end);

  ret = find_val (begin, 13, end);
  GUALCHK (ret);
  assert (ret == last);

  ret = find_prev (first, last);
  GUALCHK (ret);
  assert (ret == &testme[n-2]);

  ret = check_arr (begin, end);
  GUALCHK (ret);
  assert (!ret);

  ret = check_list (first, last);
  GUALCHK (ret);
  assert (!ret);
}

Attachment: example.exe.gz
Description: application/gunzip