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

Rafael J. Wysocki
2005-06-01T19:20:40Z

Hi,

On Wednesday, 1 of June 2005 11:27, Pavel Machek wrote:
> 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.

Oops, it looks like I have introduced these swsusp_free()s, so I'm sorry ...

> 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();
> }

I think we can move the contents of suspend_prepare_image() directly to
swsusp_save(). It's not used anywhere else.

Greets,
Rafael

--
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