[PATCH] uswsusp: automatically free the in-memory image once s2disk has finished with it

Alan Jenkins
2009-12-02T14:28:12Z

The original in-kernel suspend (swsusp) frees the in-memory hibernation
image before powering off the machine. s2disk doesn't, so there is
_much_ less free memory when it tries to power off.

This is a gratuitous difference. The userspace suspend interface
/dev/snapshot only allows the hibernation image to be read once.
Once the s2disk program has read the last page, we can free the entire
image.

This avoids a hang after writing the hibernation image which was
triggered by commit 5f8dcc21211a3d4e3a7a5ca366b469fb88117f61
"page-allocator: split per-cpu list into one-list-per-migrate-type":

[top of trace lost due to screen height]
? shrink_zone
? try_to_free_pages
? isolate_pages_global
? __alloc_pages_nodemask
? kthread
? __get_free_pages
? copy_process
? kthread
? do_fork
...

INFO: task s2disk:2036 blocked for more than 120 seconds
...
Call Trace:
...
? wait_for_common
? default_wake_function
? kthread_create
? worker_thread
? create_workqueue_thread
? worker_thread
? __create_workqueue_key
? stop_machine_create
? disable_nonboot_cpus
? hibernation_platform_enter
? snapshot_ioctl
...
? sys_ioctl
...

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
---
kernel/power/user.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/power/user.c b/kernel/power/user.c
index bf0014d..94d0210 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -165,6 +165,10 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
res = -EFAULT;
else
*offp = data->handle.offset;
+ } else {
+ swsusp_free();
+ memset(&data->handle, 0, sizeof(struct snapshot_handle));
+ data->ready = 0;
}

Unlock:
--
1.6.3.3