From mboxrd@z Thu Jan  1 00:00:00 1970
X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/336
Path: news.gmane.org!not-for-mail
From: Szabolcs Nagy <nsz@port70.net>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: New daily reports - debugging alloc.c et al
Date: Sat, 6 Aug 2011 16:34:33 +0200
Message-ID: <20110806143433.GV29562@port70.net>
References: <4E39C84F.8060705@gmail.com>
 <20110803224651.GB11437@openwall.com>
 <4E3A79B2.8090204@gmail.com>
 <4E3B331E.7050502@gmail.com>
 <4E3CC5AC.3070404@gmail.com>
 <20110806111505.GS29562@port70.net>
 <20110806115014.GT29562@port70.net>
Reply-To: musl@lists.openwall.com
NNTP-Posting-Host: lo.gmane.org
Mime-Version: 1.0
Content-Type: multipart/mixed; boundary="tT3UgwmDxwvOMqfu"
X-Trace: dough.gmane.org 1312641290 30450 80.91.229.12 (6 Aug 2011 14:34:50 GMT)
X-Complaints-To: usenet@dough.gmane.org
NNTP-Posting-Date: Sat, 6 Aug 2011 14:34:50 +0000 (UTC)
To: musl@lists.openwall.com
Original-X-From: musl-return-337-gllmg-musl=m.gmane.org@lists.openwall.com Sat Aug 06 16:34:46 2011
Return-path: <musl-return-337-gllmg-musl=m.gmane.org@lists.openwall.com>
Envelope-to: gllmg-musl@lo.gmane.org
Original-Received: from mother.openwall.net ([195.42.179.200])
	by lo.gmane.org with smtp (Exim 4.69)
	(envelope-from <musl-return-337-gllmg-musl=m.gmane.org@lists.openwall.com>)
	id 1Qphxe-0004xk-2H
	for gllmg-musl@lo.gmane.org; Sat, 06 Aug 2011 16:34:46 +0200
Original-Received: (qmail 3111 invoked by uid 550); 6 Aug 2011 14:34:45 -0000
Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:musl@lists.openwall.com>
List-Help: <mailto:musl-help@lists.openwall.com>
List-Unsubscribe: <mailto:musl-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:musl-subscribe@lists.openwall.com>
Original-Received: (qmail 3103 invoked from network); 6 Aug 2011 14:34:45 -0000
Content-Disposition: inline
In-Reply-To: <20110806115014.GT29562@port70.net>
User-Agent: Mutt/1.5.20 (2009-06-14)
Xref: news.gmane.org gmane.linux.lib.musl.general:336
Archived-At: <http://permalink.gmane.org/gmane.linux.lib.musl.general/336>


--tT3UgwmDxwvOMqfu
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

* Szabolcs Nagy <nsz@port70.net> [2011-08-06 13:50:15 +0200]:
> interestingly /proc/self/smaps does not seem to
> list all the successful mmaps.. i wonder why but
this is false, i failed to read smaps entirely

as discussed on irc here is a code that can
fill up the vm quickly and painlessly

--tT3UgwmDxwvOMqfu
Content-Type: text/x-csrc; charset=us-ascii
Content-Disposition: attachment; filename="vmfill.c"

#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>

#ifndef PAGE_SIZE
	#define PAGE_SIZE sysconf(_SC_PAGE_SIZE)
#endif

static void printvm() {
	int fd = open("/proc/self/smaps", O_RDONLY);
	char buf[4096];
	int n;

	printf("/proc/self/smaps:\n");
	fflush(stdout);
	while ((n = read(fd, buf, sizeof buf)) > 0)
		write(1, buf, n);
	close(fd);
}

static size_t mmapmax(int fd, void **p) {
	size_t i,j,n=0;

	for (i=j=SIZE_MAX/2; i>0; i/=2) {
		if ((*p=mmap(NULL, j, PROT_NONE, MAP_PRIVATE, fd, 0)) == MAP_FAILED)
			j -= i/2;
		else {
			n = j;
			munmap(*p, n);
			j += i/2;
		}
	}
	if (n && (*p=mmap(NULL, n, PROT_NONE, MAP_PRIVATE, fd, 0)) == MAP_FAILED) {
		fprintf(stderr, "failed to mmap the same amount again.\n");
		exit(1);
	}
	return n;
}

int main(int argc, char *argv[]) {
	const int fd = open("/dev/zero", O_RDWR);
	void *p[100];
	size_t n[100];
	size_t sum = 0;
	int i;
	int vmmaps = 0;

	if (argc == 2 && argv[1][0]=='-' && argv[1][1]=='v')
		vmmaps = 1;

	for (i=0; i<sizeof p/sizeof *p; i++) {
		n[i] = mmapmax(fd, p+i);
		if (!n[i])
			break;
		sum += n[i];
		printf("%d %16zu B %012zx-%012zx\n", i, n[i], (size_t)p[i], (size_t)p[i]+n[i]);
	}
	printf("mmaped %zu B in %d blocks.\n", sum, i);

	printf("try malloc:");
	for(i=0; i < 1000 && malloc(PAGE_SIZE) != NULL; i++)
		printf(".");
	printf(" %zu B\n", i*(size_t)PAGE_SIZE);

	if (vmmaps)
		printvm();
	return 0;
}

--tT3UgwmDxwvOMqfu--