[PATCH] x86_64: Fix off by one in bad_addr checking in find_e820_area

From: Robert Hentosh <robert_hentosh@dell.com>

Actually, we just stumbled on a different bug found in find_e820_area() in
e820.c.  The following code does not handle the edge condition correctly:

   while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size)
       ;
   last = addr + size;
   if ( last > ei->addr + ei->size )
       continue;

The second statement in the while loop needs to be a <= b so that it is the
logical negavite of the if (a > b) outside it. It needs to read:

   while (bad_addr(&addr, size) && addr+size <= ei->addr + ei->size)
       ;

In the case that failed bad_addr was returning an address that is exactly size
bellow the end of the e820 range.

AK: Again together with the earlier avoid edma fix this fixes
boot on a Dell PE6850/16GB

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c
index 222b5b46d2b2df6546ab01e67be1d1b92d713667..1ef6028f721ea843936b4994581c67dfa7e1b9c6 100644 (file)
--- a/arch/x86_64/kernel/e820.c
+++ b/arch/x86_64/kernel/e820.c
@@ -149,7 +149,7 @@ unsigned long __init find_e820_area(unsigned long start, unsigned long end, unsi
                        addr = start;
                if (addr > ei->addr + ei->size) 
                        continue; 
-               while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size)
+               while (bad_addr(&addr, size) && addr+size <= ei->addr+ei->size)
                        ;
                last = addr + size;
                if (last > ei->addr + ei->size)