From: Jan Kara <jack@suse.cz>
To: NeilBrown <neilb@suse.de>
Cc: Ben Greear <greearb@candelatech.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org
Subject: Re: Killing process in D state on mount to dead NFS server. (when process is in fsync)
Date: Fri, 1 Aug 2014 14:47:34 +0200 [thread overview]
Message-ID: <20140801124734.GB5431@quack.suse.cz> (raw)
In-Reply-To: <20140801075053.2120cb33@notabene.brown>
On Fri 01-08-14 07:50:53, NeilBrown wrote:
> On Thu, 31 Jul 2014 14:20:07 -0700 Ben Greear <greearb@candelatech.com> wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > On 07/31/2014 01:42 PM, NeilBrown wrote:
> > > On Thu, 31 Jul 2014 11:00:35 -0700 Ben Greear <greearb@candelatech.com> wrote:
> > >
> > >> So, this has been asked all over the interweb for years and years, but the best answer I can find is to reboot the system or create a fake NFS server
> > >> somewhere with the same IP as the gone-away NFS server.
> > >>
> > >> The problem is:
> > >>
> > >> I have some mounts to an NFS server that no longer exists (crashed/powered down).
> > >>
> > >> I have some processes stuck trying to write to files open on these mounts.
> > >>
> > >> I want to kill the process and unmount.
> > >>
> > >> umount -l will make the mount go a way, sort of. But process is still hung. umount -f complains: umount2: Device or resource busy umount.nfs: /mnt/foo:
> > >> device is busy
> > >>
> > >> kill -9 does not work on process.
> > >
> > > Kill -1 should work (since about 2.6.25 or so).
> >
> > That is -[ONE], right? Assuming so, it did not work for me.
>
> No, it was "-9" .... sorry, I really shouldn't be let out without my proof
> reader.
>
> However the 'stack' is sufficient to see what is going on.
>
> The problem is that it is blocked inside the "VM" well away from NFS and
> there is no way for NFS to say "give up and go home".
>
> I'd suggest that is a bug. I cannot see any justification for fsync to not
> be killable.
> It wouldn't be too hard to create a patch to make it so.
> It would be a little harder to examine all call paths and create a
> convincing case that the patch was safe.
> It might be herculean task to convince others that it was the right thing
> to do.... so let's start with that one.
>
> Hi Linux-mm and fs-devel people. What do people think of making "fsync" and
> variants "KILLABLE" ??
Sounds useful to me and I don't see how it could break some
application...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
To: NeilBrown <neilb-l3A5Bk7waGM@public.gmane.org>
Cc: Ben Greear <greearb-my8/4N5VtI7c+919tysfdA@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
"linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Killing process in D state on mount to dead NFS server. (when process is in fsync)
Date: Fri, 1 Aug 2014 14:47:34 +0200 [thread overview]
Message-ID: <20140801124734.GB5431@quack.suse.cz> (raw)
In-Reply-To: <20140801075053.2120cb33-wvvUuzkyo1EYVZTmpyfIwg@public.gmane.org>
On Fri 01-08-14 07:50:53, NeilBrown wrote:
> On Thu, 31 Jul 2014 14:20:07 -0700 Ben Greear <greearb-my8/4N5VtI7c+919tysfdA@public.gmane.org> wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > On 07/31/2014 01:42 PM, NeilBrown wrote:
> > > On Thu, 31 Jul 2014 11:00:35 -0700 Ben Greear <greearb-my8/4N5VtI7c+919tysfdA@public.gmane.org> wrote:
> > >
> > >> So, this has been asked all over the interweb for years and years, but the best answer I can find is to reboot the system or create a fake NFS server
> > >> somewhere with the same IP as the gone-away NFS server.
> > >>
> > >> The problem is:
> > >>
> > >> I have some mounts to an NFS server that no longer exists (crashed/powered down).
> > >>
> > >> I have some processes stuck trying to write to files open on these mounts.
> > >>
> > >> I want to kill the process and unmount.
> > >>
> > >> umount -l will make the mount go a way, sort of. But process is still hung. umount -f complains: umount2: Device or resource busy umount.nfs: /mnt/foo:
> > >> device is busy
> > >>
> > >> kill -9 does not work on process.
> > >
> > > Kill -1 should work (since about 2.6.25 or so).
> >
> > That is -[ONE], right? Assuming so, it did not work for me.
>
> No, it was "-9" .... sorry, I really shouldn't be let out without my proof
> reader.
>
> However the 'stack' is sufficient to see what is going on.
>
> The problem is that it is blocked inside the "VM" well away from NFS and
> there is no way for NFS to say "give up and go home".
>
> I'd suggest that is a bug. I cannot see any justification for fsync to not
> be killable.
> It wouldn't be too hard to create a patch to make it so.
> It would be a little harder to examine all call paths and create a
> convincing case that the patch was safe.
> It might be herculean task to convince others that it was the right thing
> to do.... so let's start with that one.
>
> Hi Linux-mm and fs-devel people. What do people think of making "fsync" and
> variants "KILLABLE" ??
Sounds useful to me and I don't see how it could break some
application...
Honza
--
Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
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WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: NeilBrown <neilb@suse.de>
Cc: Ben Greear <greearb@candelatech.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org
Subject: Re: Killing process in D state on mount to dead NFS server. (when process is in fsync)
Date: Fri, 1 Aug 2014 14:47:34 +0200 [thread overview]
Message-ID: <20140801124734.GB5431@quack.suse.cz> (raw)
In-Reply-To: <20140801075053.2120cb33@notabene.brown>
On Fri 01-08-14 07:50:53, NeilBrown wrote:
> On Thu, 31 Jul 2014 14:20:07 -0700 Ben Greear <greearb@candelatech.com> wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > On 07/31/2014 01:42 PM, NeilBrown wrote:
> > > On Thu, 31 Jul 2014 11:00:35 -0700 Ben Greear <greearb@candelatech.com> wrote:
> > >
> > >> So, this has been asked all over the interweb for years and years, but the best answer I can find is to reboot the system or create a fake NFS server
> > >> somewhere with the same IP as the gone-away NFS server.
> > >>
> > >> The problem is:
> > >>
> > >> I have some mounts to an NFS server that no longer exists (crashed/powered down).
> > >>
> > >> I have some processes stuck trying to write to files open on these mounts.
> > >>
> > >> I want to kill the process and unmount.
> > >>
> > >> umount -l will make the mount go a way, sort of. But process is still hung. umount -f complains: umount2: Device or resource busy umount.nfs: /mnt/foo:
> > >> device is busy
> > >>
> > >> kill -9 does not work on process.
> > >
> > > Kill -1 should work (since about 2.6.25 or so).
> >
> > That is -[ONE], right? Assuming so, it did not work for me.
>
> No, it was "-9" .... sorry, I really shouldn't be let out without my proof
> reader.
>
> However the 'stack' is sufficient to see what is going on.
>
> The problem is that it is blocked inside the "VM" well away from NFS and
> there is no way for NFS to say "give up and go home".
>
> I'd suggest that is a bug. I cannot see any justification for fsync to not
> be killable.
> It wouldn't be too hard to create a patch to make it so.
> It would be a little harder to examine all call paths and create a
> convincing case that the patch was safe.
> It might be herculean task to convince others that it was the right thing
> to do.... so let's start with that one.
>
> Hi Linux-mm and fs-devel people. What do people think of making "fsync" and
> variants "KILLABLE" ??
Sounds useful to me and I don't see how it could break some
application...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-08-01 12:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-31 18:00 Killing process in D state on mount to dead NFS server Ben Greear
2014-07-31 19:49 ` Malahal Naineni
2014-07-31 19:52 ` Ben Greear
2014-07-31 20:42 ` NeilBrown
2014-07-31 21:20 ` Ben Greear
2014-07-31 21:50 ` Killing process in D state on mount to dead NFS server. (when process is in fsync) NeilBrown
2014-08-01 12:47 ` Jan Kara [this message]
2014-08-01 12:47 ` Jan Kara
2014-08-01 12:47 ` Jan Kara
2014-08-02 1:21 ` Jeff Layton
2014-08-02 1:21 ` Jeff Layton
2014-08-02 1:50 ` Roger Heflin
2014-08-02 1:50 ` Roger Heflin
2014-08-02 2:07 ` Jeff Layton
2014-08-02 2:07 ` Jeff Layton
2014-08-02 2:55 ` Trond Myklebust
2014-08-02 2:55 ` Trond Myklebust
2014-08-02 3:19 ` NeilBrown
2014-08-02 3:44 ` Trond Myklebust
2014-08-02 3:44 ` Trond Myklebust
2014-08-13 15:42 ` Killing process in D state on mount to dead NFS server Ben Greear
2014-08-13 21:18 ` NeilBrown
2014-08-13 21:22 ` Ben Greear
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