From: Amerigo Wang <amwang@redhat.com>
Date: Tue, 13 Apr 2010 08:04:00 -0400
Subject: [mm] fix boot on s390x after bootmem overlap patch
Message-id: <4BC42570.9090502@redhat.com>
Patchwork-id: 24111
O-Subject: Re: [PATCH RHEL5] bootmem: don't allow reserved
	memory	to	be	overlapped with bootmem_map
Bugzilla: 550974

After checking the code again, I think my own fix which
is different from upstream is not needed, because the upstream code needs
every arch to call reserve_bootmem(bootmap, ...); explicitly. This is ugly,
because it should be done by the bootmem allocator itself. But since upstream
already chose this way, we do it too.

Below is the updated patch, which lets s390x boot normally again.

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/mm/bootmem.c b/mm/bootmem.c
index c5ab67e..72ea5e2 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -108,8 +108,6 @@ static int __init can_reserve_bootmem_core(bootmem_data_t *bdata,
 {
 	unsigned long sidx, eidx;
 	unsigned long i;
-	unsigned long boot_map = (unsigned long)bdata->node_bootmem_map;
-	unsigned long boot_map_size;
 
 	BUG_ON(!size);
 
@@ -126,11 +124,6 @@ static int __init can_reserve_bootmem_core(bootmem_data_t *bdata,
 	else
 		sidx = 0;
 
-	boot_map_size = ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE -1)/PAGE_SIZE;
-	boot_map_size *= PAGE_SIZE;
-	if (!(addr + size < boot_map || addr >=  boot_map + boot_map_size))
-		return -EBUSY;
-
 	eidx = PFN_UP(addr + size - bdata->node_boot_start);
 	if (eidx > bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start))
 		eidx = bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start);