Running linux ldconfig on tmpfs results in unkillable process

[Kostik Belousov]

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. */
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