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Date: Tue, 8 Apr 2025 10:20:58 -0700
From: Luis Chamberlain <mcgrof@kernel.org>
To: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: Christian Brauner <brauner@kernel.org>, linux-fsdevel@vger.kernel.org,
	jack@suse.cz, rafael@kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
	hch@infradead.org, david@fromorbit.com, djwong@kernel.org,
	pavel@kernel.org, peterz@infradead.org, mingo@redhat.com,
	will@kernel.org, boqun.feng@gmail.com
Subject: Re: [PATCH 0/6] power: wire-up filesystem freeze/thaw with
 suspend/resume
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References: <20250331-work-freeze-v1-0-6dfbe8253b9f@kernel.org>
 <20250401-work-freeze-v1-0-d000611d4ab0@kernel.org>
 <ddee7c1ce2d1ff1a8ced6e9b6ac707250f70e68b.camel@HansenPartnership.com>
 <20250402-radstand-neufahrzeuge-198b40c2d073@brauner>
 <2d698820ebd2e82abe8551425d82e9c387aefd66.camel@HansenPartnership.com>
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In-Reply-To: <Z_VYZAgHNGEqF7ZB@bombadil.infradead.org>

And in case its useful, to test this on a VM you'll need on libvirt:

</os>                                                                                                                                                                                                                                      
<pm>                                                                                                                                                                                                                                     
<suspend-to-mem enabled='yes'/>                                                                                                                                                                                                          
<suspend-to-disk enabled='yes'/>                                                                                                                                                                                                         
</pm>   

The litmus test which used to stall without ever returning was:

while true; do                                                                                                                                                                                                                               
dd if=/dev/zero of=/path/to/xfs/foo bs=1M count=1024 &> /dev/null
done 

To suspend you can use one of these two:

echo mem > /sys/power/state
systemctl suspend

Verify you can resume from suspend:
virsh qemu-monitor-command guest_foo 'query-current-machine'
{"return":{"wakeup-suspend-support":true},"id":"libvirt-415"}

To resume the guest:

virsh dompmwakeup guest_foo

  Luis