Re: [PATCH v2] kexec: Make a pair of map and unmap reserved pages when kdump fails to start

Minfei Huang
2015-07-01T15:06:50Z

On 07/01/15 at 04:40P, Michael Holzheu wrote:
> Hello Minfei,
>
> Regarding functionality your patch looks ok for me.
> But the code is not easy to read.
>
> What about replacing the "failure" label with "fail_unmap_pages"?

Sure. I will repost v3 to fix it.

Thanks
Minfei

>
> Michael
>
> On Tue, 30 Jun 2015 13:44:46 +0800
> Minfei Huang <mnfhuang@gmail.com> wrote:
>
> > For some arch, kexec shall map the reserved pages, then use them, when
> > we try to start the kdump service.
> >
> > Now kexec will never unmap the reserved pages, once it fails to continue
> > starting the kdump service.
> >
> > Make a pair of reserved pages in kdump starting path, whatever kexec
> > fails or not.
> >
> > Signed-off-by: Minfei Huang <mnfhuang@gmail.com>
> > ---
> > kernel/kexec.c | 26 ++++++++++++++------------
> > 1 file changed, 14 insertions(+), 12 deletions(-)
> >
> > diff --git a/kernel/kexec.c b/kernel/kexec.c
> > index 4589899..68f6dfb 100644
> > --- a/kernel/kexec.c
> > +++ b/kernel/kexec.c
> > @@ -1291,35 +1291,37 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
> > */
> >
> > kimage_free(xchg(&kexec_crash_image, NULL));
> > - result = kimage_alloc_init(&image, entry, nr_segments,
> > - segments, flags);
> > - crash_map_reserved_pages();
> > - } else {
> > - /* Loading another kernel to reboot into. */
> > -
> > - result = kimage_alloc_init(&image, entry, nr_segments,
> > - segments, flags);
> > }
> > +
> > + result = kimage_alloc_init(&image, entry, nr_segments,
> > + segments, flags);
> > if (result)
> > goto out;
> >
> > + if (flags & KEXEC_ON_CRASH)
> > + crash_map_reserved_pages();
> > +
> > if (flags & KEXEC_PRESERVE_CONTEXT)
> > image->preserve_context = 1;
> > result = machine_kexec_prepare(image);
> > if (result)
> > - goto out;
> > + goto failure;
> >
> > for (i = 0; i < nr_segments; i++) {
> > result = kimage_load_segment(image, &image->segment[i]);
> > if (result)
> > - goto out;
> > + goto failure;
> > }
> > kimage_terminate(image);
> > +
> > +failure:
> > if (flags & KEXEC_ON_CRASH)
> > crash_unmap_reserved_pages();
> > }
> > - /* Install the new kernel, and Uninstall the old */
> > - image = xchg(dest_image, image);
> > +
> > + if (result == 0)
> > + /* Install the new kernel, and Uninstall the old */
> > + image = xchg(dest_image, image);
> >
> > out:
> > mutex_unlock(&kexec_mutex);
>