Date: Thu, 5 Sep 2013 14:08:11 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Andrew Savchenko <bircoph@gmail.com>, "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: linux-kernel@vger.kernel.org, suspend-devel@lists.sourceforge.net,
        viro@zeniv.linux.org.uk, linux-pm@vger.kernel.org
Subject: Re: [Suspend-devel] [BUG] 3.7-rc regression bisected: s2disk fails
 to resume image: Processes could not be frozen, cannot continue resuming
Message-ID: <20130905120811.GC15161@amd.pavel.ucw.cz>
References: <20130812234415.7db639bb0d664e56b6ab2ab2@gmail.com>
 <20130827074843.ba1b6f62cc0a6dca8e47c06c@gmail.com>
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Hi!

Rafael, Al: apparently we have a regression caused by
ba4df2808a86f8b103c4db0b8807649383e9bd13 .

> > after a kernel update from 3.5.7 to the latest stable I found that
> > user-space resume (from suspend-1.0 aka uswsusp) no longer works.
> > Kernel-space suspend and resume work fine (e.g. echo disk
> > > /sys/power/state), problem is with user-space support. (I need
> > user-space version because it supports image encryption.)
> > 
> > After resume (essentially linuxrc) application loads image it fails
> > to apply it:
> > 
> > ========================================================
> > Processes could not be frozen, cannot continue resuming.
> > Error 11: Resource temporarily unavailable
> > 
> > You can now boot the system and lose the saved state
> > or reboot and try again.
> > 
> > [Notice that if you decide to reboot, you MUST NOT mount
> > any filesystems before a successful resume.
> > Resuming after some filesystems have been mounted
> > will badly damage these filesystems.]
> > 
> > Do you want to continue booting (Y/n)?
> > ========================================================
> > 
> > Error code wasn't originally showed, I added it to suspend tool to
> > aid debugging. Essentially freeze ioctl on /dev/snapshot fails with
> > this error.
> > 
> > I bisected a commit which introduces this bug:
> > 
> > ========================================================
> > commit ba4df2808a86f8b103c4db0b8807649383e9bd13 
> > Author: Al Viro <viro@zeniv.linux.org.uk> 
> > Date:   Tue Oct 2 15:29:10 2012 -0400 
> > 
> >     don't bother with kernel_thread/kernel_execve for launching
> > linuxrc 
> >     exec_usermodehelper_fns() will do just fine... 
> >     
> >     Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
> > ========================================================
> > 
> > In fact this commit induced/triggered at least two bugs: the first one
> > I'm facing now and the second one was fixed in commit
> > f0de17c0babe7f29381892def6b37e9181a53410:
> > make sure that /linuxrc has std{in,out,err}.
> > 
> > As a temporarily workaround for this issue I reverted all changes for
> > init/do_mounts_initrd.c up to the latest working commit
> > cb450766bcafc7bd7d40e9a5a0050745e8c68b3e considering the kernel API
> > changes (kernel_execve -> sys_execve). See linuxrc-workaround.patch.
> > I understand this isn't a proper solution, I just want to show what
> > code works for me.
> > 
> > I also found an interesting LKML discussion about s2disk and freezer
> > issue: http://www.spinics.net/lists/linux-nfs/msg38160.html
> > Maybe it is related to this bug, but patch proposed there doesn't in
> > my case.
> > 
> > Kernel config which fails with
> > ba4df2808a86f8b103c4db0b8807649383e9bd13 and works with
> > f0de17c0babe7f29381892def6b37e9181a53410 is also attached.
> > 
> > As this issue maybe hardware related, the system is 32-bit EEE PC
> > 1000H with Atom N270, 2GB RAM, 750 GB SATA drive.
> > 
> > Additional (but probably useless) information on this bug may be found
> > here: https://forums.gentoo.org/viewtopic-p-7371120.html
> 
> This bug is still here with 3.11-rc7 and 3.10.9.
> I opened a kernel bug 60802 for this issue:
> https://bugzilla.kernel.org/show_bug.cgi?id=60802
> 
> Any ideas?
> 
> Best regards,
> Andrew Savchenko


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