Re: 2.6.25.11-97.fc9 (P): idr_remove called for id=236 which is not allocated

["Vegard Nossum" <vegard.nossum@gmail.com>]

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On Fri, Aug 15, 2008 at 5:28 PM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>> ida_remove called for id=112 which is not allocated.
>> ida_remove called for id=67 which is not allocated.
>> ida_remove called for id=191 which is not allocated.
>> ida_remove called for id=23 which is not allocated.
>>
>> ..and with no backtrace, so I guess it means "not harmful". Sorry for the noise.
>
> Thats definitely not good and wants digging into further.
>

Okay!

I've attached my program. On 2.6.27-rc3 the message appears at least a
couple of times per second, so you should have no trouble in
reproducing it. On the 2.6.25 I get it maybe once a minute.

Compile with: gcc -std=gnu99


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036

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[-- Attachment #2: mknod.c --]
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#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

#ifdef CONFIG_LOGGING
static FILE *logfile;
#endif

static const char *devname = "/tmp/dev";

static void do_one(mode_t mode, unsigned int maj, unsigned int min)
{
#if CONFIG_LOGGING
	fprintf(logfile, "%d, %d\n", maj, min);
	fflush(logfile);
	fsync(fileno(logfile));
#endif

	if (mknod(devname, mode | 0644, makedev(maj, min)) == -1)
		return;

	int fd = open(devname, O_RDONLY, 0644);
	if (fd == -1)
		goto ret_mknod;

	char *ptr = mmap(NULL, getpagesize(), PROT_READ, MAP_SHARED | MAP_ANONYMOUS, fd, 0);
	if (ptr == MAP_FAILED)
		goto ret_open;

	munmap(ptr, getpagesize());

ret_open:
	close(fd);
ret_mknod:
	unlink(devname);
}

static void do_both(unsigned int maj, unsigned int min)
{
	do_one(S_IFCHR, maj, min);
	do_one(S_IFBLK, maj, min);
}

static int blacklisted(unsigned int maj, unsigned int min)
{
	/* Watchdog; will kill the system anyway */
	if (maj == 10) {
		if (min == 130)
			return 1;
		if (min >= 212 && min <= 215)
			return 1;
	}

	return 0;
}

int
main(int argc, char *argv[])
{
#ifdef CONFIG_LOGGING
	logfile = fopen("mknod-logfile.txt", "w");
	if (!logfile)
		exit(EXIT_FAILURE);
#endif

	unlink(devname);

// XXX
#ifndef CONFIG_RANDOMIZE
	srand(time(NULL));
	srand(getpid() * rand());

	while (1) {
		unsigned int i = rand() % 256;
		unsigned int j = rand() % 256;

		if (blacklisted(i, j))
			continue;

		do_both(i, j);
	}
#else
	for (unsigned int i = 0; i < 128; ++i) {
		printf("maj: %d\n", i);

		for (unsigned int j = 0; j < 128; ++j) {
			if (blacklisted(i, j))
				continue;

			do_both(i, j);
		}
	}
	doit(S_IFCHR, 10, 130);
#endif

#ifdef CONFIG_LOGGING
	fclose(logfile);
#endif
	return EXIT_SUCCESS;
}