Running linux ldconfig on tmpfs results in unkillable process

[Beat Gätzi]

On 18.01.2011 17:13, Kostik Belousov wrote:
> On Tue, Jan 18, 2011 at 04:34:10PM +0100, Beat G?tzi wrote:
>> On 18.01.2011 15:46, Kostik Belousov wrote:
>>> On Tue, Jan 18, 2011 at 03:16:27PM +0100, Beat G?tzi wrote:
>>>> Hi,
>>>>
>>>> I've a tinderbox which uses tmpfs to build ports. Every time I build a
>>>> port which executes linux ldconfig it results in an unkillable process
>>>> which uses 100% CPU. The problem is reproduceable without tinderbox:
>>>>
>>>> # uname -a
>>>> FreeBSD daedalus.network.local 9.0-CURRENT FreeBSD 9.0-CURRENT #3
>>>> r216761: Tue Dec 28 15:32:26 CET 2010
>>>> root at daedalus.network.local:/usr/obj/usr/src/sys/GENERIC  i386
>>>> # mkdir /compat/test
>>>> # mount -t tmpfs tmpfs /compat/test
>>>> # cp -Rp /compat/linux/* /compat/test/
>>>> # mount -t linprocfs linprocfs /compat/test/proc
>>>> # /compat/linux/sbin/ldconfig -r /compat/test/
>>>> # pgrep ldconfig
>>>> 3449
>>>> # procstat -i 3449 | grep KILL
>>>>  3449 ldconfig         KILL     ---
>>>> # kill -9 3449
>>>> # procstat -i 3449 | grep KILL
>>>>  3449 ldconfig         KILL     P--
>>>>
>>>> >From top(1):
>>>> PID USERNAME THR PRI NICE  SIZE   RES STATE    C  TIME   WCPU COMMAND
>>>> 3449 root     1  44    0   992K   712K CPU1    1  10:06 100.00% ldconfig
>>>>
>>>> When I reboot the machine it hangs after "All buffers synced.".
>>>>
>>>> I've uploaded some additional output of procstat and ktrace here:
>>>> http://people.freebsd.org/~beat/logs/linux-ldconfig-tmpfs.txt
>>>>
>>>> Anyone knows how to fix this?
>>> kdump for the trace of the linux binary is a garbage. You need to
>>> use linux_kdump (from ports).
>>>
>>> I think that your process is looping in the kernel, you can confirm this
>>> by dropping in the ddb and doing "bt <pid>".
>>
>> I've uploaded a screenshot from the output of bt <pid> in ddb:
>> http://people.freebsd.org/~beat/logs/linux-ldconfig-tmpfs-bt.jpg
> 
> Please try this.
> 
> diff --git a/sys/compat/linux/linux_file.c b/sys/compat/linux/linux_file.c
> index 9ff1cf0..44ad193 100644
> --- a/sys/compat/linux/linux_file.c
> +++ b/sys/compat/linux/linux_file.c
> @@ -369,7 +369,6 @@ getdents_common(struct thread *td, struct linux_getdents64_args *args,
>  	lbuf = malloc(LINUX_MAXRECLEN, M_TEMP, M_WAITOK | M_ZERO);
>  	vn_lock(vp, LK_SHARED | LK_RETRY);
>  
> -again:
>  	aiov.iov_base = buf;
>  	aiov.iov_len = buflen;
>  	auio.uio_iov = &aiov;
> @@ -506,8 +505,10 @@ again:
>  			break;
>  	}
>  
> -	if (outp == (caddr_t)args->dirent)
> -		goto again;
> +	if (outp == (caddr_t)args->dirent) {
> +		nbytes = resid;
> +		goto eof;
> +	}
>  
>  	fp->f_offset = off;
>  	if (justone)
> diff --git a/sys/fs/tmpfs/tmpfs_subr.c b/sys/fs/tmpfs/tmpfs_subr.c
> index 84a2038..62dd0bf 100644
> --- a/sys/fs/tmpfs/tmpfs_subr.c
> +++ b/sys/fs/tmpfs/tmpfs_subr.c
> @@ -827,9 +827,10 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, off_t *cntp)
>  		/* Copy the new dirent structure into the output buffer and
>  		 * advance pointers. */
>  		error = uiomove(&d, d.d_reclen, uio);
> -
> -		(*cntp)++;
> -		de = TAILQ_NEXT(de, td_entries);
> +		if (error == 0) {
> +			(*cntp)++;
> +			de = TAILQ_NEXT(de, td_entries);
> +		}
>  	} while (error == 0 && uio->uio_resid > 0 && de != NULL);
>  
>  	/* Update the offset and cache. */

This patch solves the problem.

Thanks a lot!
Beat