linux-kernel - [PATCH 3.12 032/123] kexec: allocate the kexec control page with KEXEC_CONTROL_MEMORY

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Date:	Tue,  4 Aug 2015 16:39:36 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 032/123] kexec: allocate the kexec control page with KEXEC_CONTROL_MEMORY_GFP

From: Martin Schwidefsky <schwidefsky@...ibm.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 7e01b5acd88b3f3108d8c4ce44e3205d67437202 upstream.

Introduce KEXEC_CONTROL_MEMORY_GFP to allow the architecture code
to override the gfp flags of the allocation for the kexec control
page. The loop in kimage_alloc_normal_control_pages allocates pages
with GFP_KERNEL until a page is found that happens to have an
address smaller than the KEXEC_CONTROL_MEMORY_LIMIT. On systems
with a large memory size but a small KEXEC_CONTROL_MEMORY_LIMIT
the loop will keep allocating memory until the oom killer steps in.

Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/s390/include/asm/kexec.h | 3 +++
 include/linux/kexec.h         | 4 ++++
 kernel/kexec.c                | 2 +-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/kexec.h b/arch/s390/include/asm/kexec.h
index 694bcd6bd927..2f924bc30e35 100644
--- a/arch/s390/include/asm/kexec.h
+++ b/arch/s390/include/asm/kexec.h
@@ -26,6 +26,9 @@
 /* Not more than 2GB */
 #define KEXEC_CONTROL_MEMORY_LIMIT (1UL<<31)
 
+/* Allocate control page with GFP_DMA */
+#define KEXEC_CONTROL_MEMORY_GFP GFP_DMA
+
 /* Maximum address we can use for the crash control pages */
 #define KEXEC_CRASH_CONTROL_MEMORY_LIMIT (-1UL)
 
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 5fd33dc1fe3a..66e3687b401b 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -26,6 +26,10 @@
 #error KEXEC_CONTROL_MEMORY_LIMIT not defined
 #endif
 
+#ifndef KEXEC_CONTROL_MEMORY_GFP
+#define KEXEC_CONTROL_MEMORY_GFP GFP_KERNEL
+#endif
+
 #ifndef KEXEC_CONTROL_PAGE_SIZE
 #error KEXEC_CONTROL_PAGE_SIZE not defined
 #endif
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 4c9dcffd1750..316216c38fb9 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -432,7 +432,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
 	do {
 		unsigned long pfn, epfn, addr, eaddr;
 
-		pages = kimage_alloc_pages(GFP_KERNEL, order);
+		pages = kimage_alloc_pages(KEXEC_CONTROL_MEMORY_GFP, order);
 		if (!pages)
 			break;
 		pfn   = page_to_pfn(pages);
-- 
2.5.0

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