From 7041bee115a3ceee2d5aec3a23640ec99acf493f Mon Sep 17 00:00:00 2001 From: Petr Tesarik <ptesarik@suse.cz> Date: Mon, 23 Jun 2014 13:22:03 -0700 Subject: [PATCH] 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. Signed-off-by: Petr Tesarik <ptesarik@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Shaohua Li <shli@kernel.org> Cc: Alexey Kardashevskiy <aik@ozlabs.ru> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- 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 3c545b48aeabd..8304959ad3364 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -360,6 +360,9 @@ 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 6748688813d06..369f41a941248 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1617,6 +1617,7 @@ 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(); -- 2.39.5