2008-02-09 12:05:10

by Martin Schwidefsky

[permalink] [raw]
Subject: [patch 05/11] VMEM_MAX_PHYS overflow on 31 bit.

From: Martin Schwidefsky <[email protected]>

With the new space saving spinlock_t and a non-debug configuration
the struct page only has 32 bytes for 31 bit s390. The causes an
overflow in the calculation of VMEM_MAX_PHYS which renders the
kernel unbootable.

Signed-off-by: Martin Schwidefsky <[email protected]>
---

include/asm-s390/pgtable.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

Index: quilt-2.6/include/asm-s390/pgtable.h
===================================================================
--- quilt-2.6.orig/include/asm-s390/pgtable.h
+++ quilt-2.6/include/asm-s390/pgtable.h
@@ -127,8 +127,9 @@ extern char empty_zero_page[PAGE_SIZE];
* mapping. This needs to be calculated at compile time since the size of the
* VMEM_MAP is static but the size of struct page can change.
*/
-#define VMEM_MAX_PHYS min(VMALLOC_START, ((VMEM_MAP_END - VMALLOC_END) / \
- sizeof(struct page) * PAGE_SIZE) & ~((16 << 20) - 1))
+#define VMEM_MAX_PAGES ((VMEM_MAP_END - VMALLOC_END) / sizeof(struct page))
+#define VMEM_MAX_PFN min(VMALLOC_START >> PAGE_SHIFT, VMEM_MAX_PAGES)
+#define VMEM_MAX_PHYS ((VMEM_MAX_PFN << PAGE_SHIFT) & ~((16 << 20) - 1))
#define VMEM_MAP ((struct page *) VMALLOC_END)

/*

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.