unkillable process stuck in "nfsaio"

[Kostik Belousov]

On Thu, Mar 16, 2006 at 03:16:26PM -0500, Mikhail Teterin wrote:
> I was creating a big .iso image using mkisofs. The file was written over NFS 
> to a remote share.
> 
> When I decided to stop it and pressed Ctrl-C, the process hung and remains 
> unkillable (even with -9).
> 
> Pressing Ctrl-T prints the following:
> 
> load: 0.04  cmd: mkisofs 48414 [nfsaio] 0.70u 5.89s 0% 8784k
> 
> The share is mounted as:
> 
> 	pandora:/backup on /tmp/.a/pandora/backup (nfs, nosuid)
> 
> The client is FreeBSD 6.1-PRERELEASE #0: Mon Mar 13 ... i386.
> 
> The server information is deliberately witheld, because it should be possible 
> to abort and kill the client-side writer regardless of the server version :-)
> 
> Thanks in advance for fixing this bug. Yours,
> 
> 	-mi

Just out of curiosity:

could you, please, test this little patch:

Index: sys/nfsclient/nfs_bio.c
===================================================================
RCS file: /usr/local/arch/ncvs/src/sys/nfsclient/nfs_bio.c,v
retrieving revision 1.154
diff -u -r1.154 nfs_bio.c
--- sys/nfsclient/nfs_bio.c	21 Nov 2005 19:23:46 -0000	1.154
+++ sys/nfsclient/nfs_bio.c	17 Mar 2006 09:38:40 -0000
@@ -1355,7 +1355,6 @@
 				if (error2)
 					return (error2);
 				if (slpflag == PCATCH) {
-					slpflag = 0;
 					slptimeo = 2 * hz;
 				}
 			}

It seems from the code that the condition should be easily
triggered.

Thanks.
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