Re: 2.6.23-mm1

[KAMEZAWA Hiroyuki]

I noticed 32bit binary on x86_64 behavior is changed on 2.6.23-mm1.

This is a result of pmap after process returns -ENOMEM.(see attached program)
== on 2.6.23 ==
errno 12
3531:   ./malloc
0000000000001000   6272K -----    [ anon ]
0000000000621000    100K r-x--  /lib/ld-2.5.so
000000000063a000      4K r----  /lib/ld-2.5.so
000000000063b000      4K rw---  /lib/ld-2.5.so
000000000063c000      8K -----    [ anon ]
000000000063e000   1244K r-x--  /lib/libc-2.5.so
0000000000775000      8K r----  /lib/libc-2.5.so
0000000000777000      4K rw---  /lib/libc-2.5.so
0000000000778000     12K rw---    [ anon ]
000000000077b000 123700K -----    [ anon ]
0000000008048000      4K r-x--  /home/kamezawa/malloc
0000000008049000      4K rw---  /home/kamezawa/malloc
000000000804a000 3929824K -----    [ anon ]
00000000f7f02000      8K rw---    [ anon ]
00000000f7f04000    100K -----    [ anon ]
00000000f7f1d000      4K rw---    [ anon ]
00000000f7f1e000 131812K -----    [ anon ]
00000000fffd7000     84K rw---    [ stack ]
00000000fffec000     72K -----    [ anon ]
00000000ffffe000      4K r-x--    [ anon ]
 total          4193272K
==

== on 2.6.23-mm1==
errno 12
3504:   ./malloc
0000000000621000    100K r-x--  /lib/ld-2.5.so
000000000063a000      4K r----  /lib/ld-2.5.so
000000000063b000      4K rw---  /lib/ld-2.5.so
000000000063e000   1244K r-x--  /lib/libc-2.5.so
0000000000775000      8K r----  /lib/libc-2.5.so
0000000000777000      4K rw---  /lib/libc-2.5.so
0000000000778000     12K rw---    [ anon ]
0000000008048000      4K r-x--  /home/kamezawa/malloc
0000000008049000      4K rw---  /home/kamezawa/malloc
0000000055555000      4K rw---    [ anon ]
0000000055556000    100K -----    [ anon ]
000000005556f000      8K rw---    [ anon ]
0000000055671000 2789016K -----    [ anon ]
00000000ffa17000     84K rw---    [ stack ]
00000000ffa2c000   5960K -----    [ anon ]
00000000ffffe000      4K r-x--    [ anon ]
 total          2796560K
==

Maybe get_unmapped_area() had some change.
Is this intended ?

Thanks,
-Kame
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>



#define PAGESIZE (4096)

int main(int argc, char *argv[])
{
	char *c,*safe;
	pid_t pid;
	char buffer[256];
	int err;
	pid = getpid();
	sprintf(buffer,"/usr/bin/pmap %d", pid);
	safe = malloc(1024*1024);
	while (1) {
		c = mmap(NULL, PAGESIZE, PROT_NONE, MAP_ANON | MAP_PRIVATE, 0, 0);
		if (c == MAP_FAILED) {
			err = errno;
			break;
		}
	}
	free(safe);
	printf("errno %d\n",err);
	system(buffer);
}