[tip:x86/mm] x86/mm: Avoid overlap the fixmap area on i386

tip-bot for Minfei Huang
2014-10-28T11:24:47Z

Commit-ID: 96e70f83285676d8794f62f3c294d0247bef6b21
Gitweb: http://git.kernel.org/tip/96e70f83285676d8794f62f3c294d0247bef6b21
Author: Minfei Huang <mnfhuang@gmail.com>
AuthorDate: Thu, 23 Oct 2014 23:36:17 +0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Oct 2014 12:21:48 +0100

x86/mm: Avoid overlap the fixmap area on i386

It is a problem when configuring high memory off where the
vmalloc reserve area could end up overlapping the early_ioremap
fixmap area on i386.

The ordering of the VMALLOC_RESERVE space is:

FIXADDR_TOP
fixed_addresses
FIXADDR_START
early_ioremap fixed addresses
FIXADDR_BOOT_START
Persistent kmap area
PKMAP_BASE
VMALLOC_END
Vmalloc area
VMALLOC_START
high_memory

The available address we can use is lower than
FIXADDR_BOOT_START. So we will set the kmap boundary below the
FIXADDR_BOOT_START, if we configure high memory.

If we configure high memory, the vmalloc reserve area should
end up to PKMAP_BASE, otherwise should end up to
FIXADDR_BOOT_START.

Signed-off-by: Minfei Huang <mnfhuang@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/6B680A9E-6CE9-4C96-934B-CB01DCB58278@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/pgtable_32_types.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/pgtable_32_types.h b/arch/x86/include/asm/pgtable_32_types.h
index ed5903b..2ac5fc8 100644
--- a/arch/x86/include/asm/pgtable_32_types.h
+++ b/arch/x86/include/asm/pgtable_32_types.h
@@ -43,7 +43,7 @@ extern bool __vmalloc_start_set; /* set once high_memory is set */
#ifdef CONFIG_HIGHMEM
# define VMALLOC_END (PKMAP_BASE - 2 * PAGE_SIZE)
#else
-# define VMALLOC_END (FIXADDR_START - 2 * PAGE_SIZE)
+# define VMALLOC_END (FIXADDR_BOOT_START - 2 * PAGE_SIZE)
#endif

#define MODULES_VADDR VMALLOC_START