Re: [PATCH V3] ia64/mm: fix a bad_page bug when crash kernel booting

Matt Fleming
2013-02-13T10:07:08Z

On Thu, 2013-02-07 at 14:09 +0800, Xishi Qiu wrote:
> > Sorry, this bug will be happen when use Sparse-Memory(section is valid, but last
>
> > several pages are invalid). If use Flat-Memory, crash kernel will boot successfully.
> > I think the following patch would be better.
> >
> > Hi Andrew, will you just ignore the earlier patch and consider the following one? :>
> >
> > Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
> > ---
> > arch/ia64/mm/init.c | 2 ++
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
> > index 082e383..23f2ee3 100644
> > --- a/arch/ia64/mm/init.c
> > +++ b/arch/ia64/mm/init.c
> > @@ -213,6 +213,8 @@ free_initrd_mem (unsigned long start, unsigned long end)
> > for (; start < end; start += PAGE_SIZE) {
> > if (!virt_addr_valid(start))
> > continue;
> > + if ((start >> PAGE_SHIFT) >= max_low_pfn)
>
> I confused the vaddr and paddr, really sorry for it.
>
> In efi_init() memory aligns in IA64_GRANULE_SIZE(16M). If set "crashkernel\x1024M-:600M"
> and use sparse memory model, when crash kernel booting it changes [128M-728M] to [128M-720M].
> But initrd memory is in [709M-727M], and virt_addr_valid() *can not* check the invalid pages
> when freeing initrd memory. There are some pages missed at the end of the seciton.
>
> ChangeLog V3:
> fixed vaddr mistake
> ChangeLog V2:
> add invalid pages check when freeing initrd memory
>
> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
> ---
> arch/ia64/mm/init.c | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
> index 082e383..8a269f8 100644
> --- a/arch/ia64/mm/init.c
> +++ b/arch/ia64/mm/init.c
> @@ -173,6 +173,7 @@ void __init
> free_initrd_mem (unsigned long start, unsigned long end)
> {
> struct page *page;
> + unsigned long pfn;
> /*
> * EFI uses 4KB pages while the kernel can use 4KB or bigger.
> * Thus EFI and the kernel may have different page sizes. It is
> @@ -213,6 +214,9 @@ free_initrd_mem (unsigned long start, unsigned long end)
> for (; start < end; start += PAGE_SIZE) {
> if (!virt_addr_valid(start))
> continue;
> + pfn = __pa(start) >> PAGE_SHIFT;
> + if (pfn >= max_low_pfn)
> + continue;
> page = virt_to_page(start);
> ClearPageReserved(page);
> init_page_count(page);

I would have presumed that fixing this bug would involve modifying the
ia64-specific kexec code?

Tony, Fenghua? Any thoughts?