Re: [PATCH] Don't explode on swsusp failure to find swap

Pavel Machek
2005-06-01T09:27:42Z

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Hi!

> > > > If we specify a swap device for swsusp using resume= kernel argument and
> > > > that device doesn't exist in the swap list, we end up calling
> > > > swsusp_free() before we have allocated pagedir_save. That causes us to
> > > > explode when trying to free it.
> > > >
> > > > Pavel, does that look right ?
> > >
> > > It looks like a workaround. We should not call swsusp_free in case
> > > device does not exists. Quick look did not reveal where the bug comes
> > > from, can you try to trace it?
> > > Pavel
> >
> > Well, the bug comes from arch code calling swsusp_save() which fails,
> > then we call swsusp_free()
>
> More specifically, arch suspend calls swsusp_save().
>
> It fails and returns the error to the arch asm code, which itself
> returns it to it's caller swsusp_suspend(), which does that:
>
> if ((error = swsusp_arch_suspend()))
> swsusp_free();

Ugh, swsusp_free should be totally unneccessary at this point; only
error returns are from the time before anything is allocated.

Does something like this help?

diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -975,13 +975,6 @@ extern asmlinkage int swsusp_arch_resume

asmlinkage int swsusp_save(void)
{
- int error = 0;
-
- if ((error = swsusp_swap_check())) {
- printk(KERN_ERR "swsusp: FATAL: cannot find swap device, try "
- "swapon -a!\n");
- return error;
- }
return suspend_prepare_image();
}

@@ -999,12 +992,19 @@ int swsusp_suspend(void)
*/
if ((error = device_power_down(PMSG_FREEZE))) {
local_irq_enable();
- swsusp_free();
return error;
}
+
+ if ((error = swsusp_swap_check())) {
+ printk(KERN_ERR "swsusp: FATAL: cannot find swap device, try "
+ "swapon -a!\n");
+ local_irq_enable();
+ return error;
+ }
+
save_processor_state();
if ((error = swsusp_arch_suspend()))
- swsusp_free();
+ printk("Error %d suspending\n", error);
/* Restore control flow magically appears here */
restore_processor_state();
BUG_ON (nr_copy_pages_check != nr_copy_pages);