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Date:      Sat, 27 Feb 1999 11:59:28 -0800 (PST)
From:      Jonathan Hanna <pangolin@home.com>
To:        current@freebsd.org
Subject:   lockmgr panic with mmap()
Message-ID:  <19990227195928.SCCF11952.mail.rdc1.bc.wave.home.com@cr1003333-a.crdva1.bc.wave.home.com>
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[-- Attachment #1 --]

The attached program sometimes causes a lockmgr panic. I do not think is always
did. I am running 4.0-CURRENT form Feb 19.

The trace is:
        panic lockmgr: locking against self
        lockmgr
        mv_map_growstack
        grow_stack
        trap_pfault
        trap
        calltrap
        subyte
        syscall
        ...
        
A command on a running image such as this usually does it, though I do not know what
conditions are neccessary:

        fincore /usr/local/netscape-4.5/communicator-4.5.bin

Jonathan Hanna <pangolin@home.com>


[-- Attachment #2 --]

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <machine/param.h>

/*
** print pages of file in core
*/

void usage(char *name)
{
	printf("Usage: %s [-ns] files...\n",name);
	printf("\t-n\t\tDo not print filename\n");
	printf("\t-o\t\tOnly print files with at least one page in core\n");
	printf("\t-s\t\tDo not print file size in pages\n");
}

main(int ac,char **av)
{
	int c;
	int print_name = 1;
	int print_sizepages = 1;
	int only_nonzero = 0;
	int status = 0;

	while((c = getopt(ac,av,"nos")) != -1) {
		switch(c) {
		case 'n':
			print_name = 0;
			break;
		case 'o':
			only_nonzero = 1;
			break;
		case 's':
			print_sizepages = 0;
			break;
		default:
			usage(av[0]);
			exit(1);
		}
	}
	for(; optind < ac ; optind++) {
		int fd;
		int pind,pcount;
		caddr_t addr;
		struct stat statbuf;
		size_t len;
		size_t numpages;
		char *pvec;

		if ((fd = open(av[optind],O_RDONLY)) < 0) {
			perror(av[optind]);
			status = 1;
			continue;
		}
		if (fstat(fd,&statbuf)) {
			perror("fstat");
			close(fd);
			status = 1;
			continue;
		}
		len = statbuf.st_size;
		numpages = len/PAGE_SIZE + ((len % PAGE_SIZE) != 0);

		if (! (statbuf.st_mode & (S_IFREG|S_IFCHR))) {
			pcount = 0;
		} else if (len) {
			if ((addr = mmap(0,len,PROT_READ,MAP_SHARED,fd,0)) == MAP_FAILED) {
				perror("mmap");
				exit(1);
			}
			pvec = malloc(numpages);
			if (mincore(addr,len,pvec))
			{
				perror("mincore");
				exit(1);
			}
			for(pcount = 0,pind = 0 ; pind < numpages ; pind++) {
				if (pvec[pind]) pcount++;
			}
			free(pvec);
			if (munmap(addr,len)) {
				perror("munmap");
				exit(1);
			}
		} else {
			pcount = 0;
		}
		if (pcount || !only_nonzero) {
			if (print_name) printf("%s: ",av[optind]);
			printf("%d",pcount);
			if (print_sizepages) printf("/%d",numpages);
			printf("\n");
		}
		close(fd);
	}
	exit(status);
}

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