On Fri, 11 Apr 2014 17:50:39 +0200 Petr Tesarik <ptesarik at suse.cz> wrote: > To allow filtering of huge pages, makedumpfile must be able to > identify them in the dump. This can be done by checking the > appropriate page flag, so communicate its value to makedumpfile > through the VMCOREINFO interface. > > There's only one small catch. Depending on how many page flags > are available on a given architecture, this bit can be called > PG_head or PG_compound. > > I sent a similar patch back in 2012, but Eric Biederman did not > like using an #ifdef. So, this time I'm adding a common symbol > (PG_head_mask) instead. Any opinion on this patch? TIA, Petr T > See https://lkml.org/lkml/2012/11/28/91 for the previous version. > > Signed-off-by: Petr Tesarik <ptesarik at suse.cz> > --- > include/linux/page-flags.h | 3 +++ > kernel/kexec.c | 1 + > 2 files changed, 4 insertions(+) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index d1fe1a7..bc2007e 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -348,6 +348,9 @@ static inline void ClearPageCompound(struct page > *page) ClearPageHead(page); > } > #endif > + > +#define PG_head_mask ((1L << PG_head)) > + > #else > /* > * Reduce page flag use as much as possible by overlapping > diff --git a/kernel/kexec.c b/kernel/kexec.c > index c8380ad..e6f3aec 100644 > --- a/kernel/kexec.c > +++ b/kernel/kexec.c > @@ -1622,6 +1622,7 @@ static int __init crash_save_vmcoreinfo_init(void) > #ifdef CONFIG_MEMORY_FAILURE > VMCOREINFO_NUMBER(PG_hwpoison); > #endif > + VMCOREINFO_NUMBER(PG_head_mask); > VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE); > > arch_crash_save_vmcoreinfo();
