linux-kernel - [PATCH] x86/mm, hibernate: Fix misjudgment of register setup

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Date:	Fri, 30 Jan 2015 11:58:20 +0800
From:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Ingo Molnar <mingo@...nel.org>, Pavel Machek <pavel@....cz>
Cc:	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
	linux-kernel@...r.kernel.org, "Lee, Chun-Yi" <jlee@...e.com>,
	Len Brown <len.brown@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>, Yinghai Lu <yinghai@...nel.org>,
	Takashi Iwai <tiwai@...e.de>
Subject: [PATCH] x86/mm, hibernate: Fix misjudgment of register setup_data page to nosave region

The reserve setup_data action break usable regions to not align to
page size. As following case:

BIOS-e820: [mem 0x0000000000088000-0x00000000000bffff] reserved
BIOS-e820: [mem 0x0000000000100000-0x0000000094caffff] usable
...
e820: update [mem 0x93c5f018-0x93c6f057] usable ==> usable	/* reserve setup_data */
e820: update [mem 0x93c4f018-0x93c5e057] usable ==> usable	/* reserve setup_data */
...
reserve setup_data: [mem0x0000000000088000-0x00000000000bffff] reserved
reserve setup_data: [mem0x0000000000100000-0x0000000093c4f017] usable /* not align */
reserve setup_data: [mem0x0000000093c4f018-0x0000000093c5e057] usable /* not align */
reserve setup_data: [mem0x0000000093c5e058-0x0000000093c5f017] usable /* not align */
reserve setup_data: [mem0x0000000093c5f018-0x0000000093c6f057] usable /* not align */
reserve setup_data: [mem0x0000000093c6f058-0x0000000094caffff] usable

The codes in e820_mark_nosave_regions() check pfn of each e820
entry to find out the hole between two entries then register it to
nosave region. This logic misjudges the non-align but continuous usable
region, then register one page in usable region to nosave. As following:

PM: Registered nosave memory: [mem 0x000c0000-0x000fffff]
PM: Registered nosave memory: [mem 0x93c4f000-0x93c4ffff] /* misjudgment */
PM: Registered nosave memory: [mem 0x93c5e000-0x93c5efff] /* misjudgment */
PM: Registered nosave memory: [mem 0x93c5f000-0x93c5ffff] /* misjudgment */
PM: Registered nosave memory: [mem 0x93c6f000-0x93c6ffff] /* misjudgment */
PM: Registered nosave memory: [mem 0x94cb0000-0x960affff]

The issue causes some usable pages didn't collect to hibernate snapshot image.
And, it also misjudges a usable page in nosave regions then hibernate resuming
process interrupted by the unsafe pages checking:
	https://bugzilla.opensuse.org/show_bug.cgi?id=913885

This patch changed the code in e820_mark_nosave_regions() to check the
address instead of pfn to avoid above issue.

Cc: Pavel Machek <pavel@....cz>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Len Brown <len.brown@...el.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: Takashi Iwai <tiwai@...e.de>
Cc: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
---
 arch/x86/kernel/e820.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 49f8864..6eae021 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -687,15 +687,16 @@ void __init parse_e820_ext(u64 phys_addr, u32 data_len)
 void __init e820_mark_nosave_regions(unsigned long limit_pfn)
 {
 	int i;
-	unsigned long pfn = 0;
+	unsigned long pfn = 0, pfnaddr = 0;
 
 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 
-		if (pfn < PFN_UP(ei->addr))
+		if (pfnaddr < ei->addr)
 			register_nosave_region(pfn, PFN_UP(ei->addr));
 
-		pfn = PFN_DOWN(ei->addr + ei->size);
+		pfnaddr = ei->addr + ei->size;
+		pfn = PFN_DOWN(pfnaddr);
 		if (ei->type != E820_RAM && ei->type != E820_RESERVED_KERN)
 			register_nosave_region(PFN_UP(ei->addr), pfn);
 
-- 
1.8.4.5

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