On Thu, 12 Jun 2014 17:04:36 +0200 Petr Tesarik <ptesarik at suse.cz> wrote: > On Wed, 11 Jun 2014 13:24:22 -0400 > Vivek Goyal <vgoyal at redhat.com> wrote: > > > On Wed, Jun 11, 2014 at 01:20:42PM +0200, Petr Tesarik wrote: > > > On Tue, 10 Jun 2014 11:35:54 -0400 > > > Vivek Goyal <vgoyal at redhat.com> wrote: > > > > > > > On Mon, Jun 09, 2014 at 03:31:53PM -0700, Andrew Morton wrote: > > > > > > > > > > > > > > > Guys, could you please review this one? > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > From: Petr Tesarik <ptesarik at suse.cz> > > > > > Subject: kexec: save PG_head_mask in VMCOREINFO > > > > > > > > > > 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. > > > > > > > > > > See https://lkml.org/lkml/2012/11/28/91 for the previous version. > > > > > > > > > > > > > Hi Petr, > > > > > > > > I went through previous conversation and personally I like that patch > > > > better. > > > > > > > > We already have so many exports in vmcoreinfo which are conditional > > > > based on config options. Adding one more should be just fine. And as > > > > you said that it should not bitrot as it will most likely lead > > > > to complication failures if things shift around. > > > > > > > > Does this patch compile with !CONFIG_PAGEFLAGS_EXTENDED. I did not see > > > > a definition of PG_head_mask in that case. > > > > > > With !CONFIG_PAGEFLAGS_EXTENDED, the definition of PG_head_mask is > > > already there (and has been for quite some time). > > > > Oh.., I had not noticed that. Thanks. > > > > > > > > > So I would say post your patch again, I will ack it. CC Eric and hopefully > > > > he does not have any objections to it. Oh, it seems you're still waiting for Eric's opinion, but I didn't notice that he wasn't in Cc yet. > > > Er, I'm not sure which patch you mean. The original one (with > > > conditional PG_head/PG_compound), or the new one (with PG_head_mask)? > > > > Given PG_head_mask is already defined for !CONFIG_PAGEFLAGS_EXTENDED, I > > am fine with this version too. > > > > So bottom line, I am fine with either version. Given that Andrew > > already seems to have this one queued, I will ack this one. > > > > Acked-by: Vivek Goyal <vgoyal at redhat.com> Eric, based on Vivek's feedback, do you have any objections to the following patch: http://ozlabs.org/~akpm/mmotm/broken-out/kexec-save-pg_head_mask-in-vmcoreinfo.patch Thanks, Petr Tesarik > Thank you! > > As a side note, I personally like this new version better, because it > does not propagate the differences between CONFIG_PAGEFLAGS_EXTENDED > and !CONFIG_PAGEFLAGS_EXTENDED to VMCOREINFO (and consequently to all > tools that want to use it). > > Petr Tesarik > > > > > > Signed-off-by: Petr Tesarik <ptesarik at suse.cz> > > > > > Cc: Eric Biederman <ebiederm at xmission.com> > > > > > Cc: Paul Mackerras <paulus at samba.org> > > > > > Cc: Fengguang Wu <fengguang.wu at intel.com> > > > > > Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org> > > > > > Cc: Shaohua Li <shli at kernel.org> > > > > > Cc: Alexey Kardashevskiy <aik at ozlabs.ru> > > > > > Cc: Sasha Levin <sasha.levin at oracle.com> > > > > > Cc: Vivek Goyal <vgoyal at redhat.com> > > > > > Signed-off-by: Andrew Morton <akpm at linux-foundation.org> > > > > > --- > > > > > > > > > > include/linux/page-flags.h | 3 +++ > > > > > kernel/kexec.c | 1 + > > > > > 2 files changed, 4 insertions(+) > > > > > > > > > > diff -puN include/linux/page-flags.h~kexec-save-pg_head_mask-in-vmcoreinfo include/linux/page-flags.h > > > > > --- a/include/linux/page-flags.h~kexec-save-pg_head_mask-in-vmcoreinfo > > > > > +++ a/include/linux/page-flags.h > > > > > @@ -350,6 +350,9 @@ static inline void ClearPageCompound(str > > > > > ClearPageHead(page); > > > > > } > > > > > #endif > > > > > + > > > > > +#define PG_head_mask ((1L << PG_head)) > > > > > + > > > > > #else > > > > > /* > > > > > * Reduce page flag use as much as possible by overlapping > > > > > diff -puN kernel/kexec.c~kexec-save-pg_head_mask-in-vmcoreinfo kernel/kexec.c > > > > > --- a/kernel/kexec.c~kexec-save-pg_head_mask-in-vmcoreinfo > > > > > +++ a/kernel/kexec.c > > > > > @@ -1617,6 +1617,7 @@ static int __init crash_save_vmcoreinfo_ > > > > > #ifdef CONFIG_MEMORY_FAILURE > > > > > VMCOREINFO_NUMBER(PG_hwpoison); > > > > > #endif > > > > > + VMCOREINFO_NUMBER(PG_head_mask); > > > > > VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE); > > > > > > > > > > arch_crash_save_vmcoreinfo(); > > > > > _ >
