Re: 2.6.20 kernel hang with USB drive and vfat doing ftruncate

From: OGAWA Hirofumi
Date: Sun Feb 18 2007 - 11:10:48 EST


Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx> writes:

> I'm seeing an issue with a stock 2.6.20 kernel running on an embedded
> PPC. I've got a usb flash drive plugged in and the filesystem on the
> drive is vfat. Running with 64M and no swap.
>
> If I execute a series of large (100M+) ftruncate() on the disk the
> kernel will hang and never return. It seems to be stuck in the idle
> loop().
>
> The following is the test program I'm running:
>
> #include <sys/mman.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <stdio.h>
> #include <unistd.h>
> #include <errno.h>
>
> void usage (void)
> {
> printf ("truncate_test <filename> <size>\n\n");
> }
>
> int main(int argc, char *argv[])
> {
> int fd, i;
> int ret = 0;
> unsigned int len;
>
> if (argc != 3) {
> printf("Invalid number of arguments\n\n");
> usage();
> exit(1);
> }
>
> fd = open(argv[1], O_CREAT|O_RDWR|O_TRUNC, S_IRWXU);
> len = strtoul(argv[2], NULL, 0);
>
> ret = ftruncate(fd, len);
>
> if (ret)
> printf ("ftruncate ret = %d %d\n", ret, errno);
>
> close(fd);
>
> return ret;
> }
>
> I usually run the following twice to get the hang state:
>
> time ./trunc_test bar 100000000 &
> time ./trunc_test baz 100000000 &
>
> I was wondering if anyone had any suggestions on what to poke at next
> to try and figure out what is going on.

Can you check /sys/block/xxx/stat or something to make sure there is
no outstanding IO request?

It seems to be no response from the lower layer...
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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