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Subject[tip:x86/urgent] x86, range: fix missing merge during add range
Commit-ID:  fbe06b7bae7c9cf6ab05168fce5ee93b2f4bae7c
Gitweb: http://git.kernel.org/tip/fbe06b7bae7c9cf6ab05168fce5ee93b2f4bae7c
Author: Yinghai Lu <yinghai@kernel.org>
AuthorDate: Fri, 17 May 2013 11:49:10 -0700
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Fri, 17 May 2013 11:49:10 -0700

x86, range: fix missing merge during add range

Christian found v3.9 does not work with E350 with EFI is enabled.

[ 1.658832] Trying to unpack rootfs image as initramfs...
[ 1.679935] BUG: unable to handle kernel paging request at ffff88006e3fd000
[ 1.686940] IP: [<ffffffff813661df>] memset+0x1f/0xb0
[ 1.692010] PGD 1f77067 PUD 1f7a067 PMD 61420067 PTE 0

but early memtest report all memory could be accessed without problem.

early page table is set in following sequence:
[ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
[ 0.000000] init_memory_mapping: [mem 0x6e600000-0x6e7fffff]
[ 0.000000] init_memory_mapping: [mem 0x6c000000-0x6e5fffff]
[ 0.000000] init_memory_mapping: [mem 0x00100000-0x6bffffff]
[ 0.000000] init_memory_mapping: [mem 0x6e800000-0x6ea07fff]
but later efi_enter_virtual_mode try set mapping again wrongly.
[ 0.010644] pid_max: default: 32768 minimum: 301
[ 0.015302] init_memory_mapping: [mem 0x640c5000-0x6e3fcfff]
that means it fails with pfn_range_is_mapped.

It turns out that we have a bug in add_range_with_merge and it does not
merge range properly when new add one fill the hole between two exsiting
ranges. In the case when [mem 0x00100000-0x6bffffff] is the hole between
[mem 0x00000000-0x000fffff] and [mem 0x6c000000-0x6e7fffff].

Fix the add_range_with_merge by calling itself recursively.

Reported-by: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/CAE9FiQVofGoSk7q5-0irjkBxemqK729cND4hov-1QCBJDhxpgQ@mail.gmail.com
Cc: <stable@vger.kernel.org> v3.9
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
kernel/range.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/range.c b/kernel/range.c
index 071b0ab..eb911db 100644
--- a/kernel/range.c
+++ b/kernel/range.c
@@ -48,9 +48,11 @@ int add_range_with_merge(struct range *range, int az, int nr_range,
final_start = min(range[i].start, start);
final_end = max(range[i].end, end);

- range[i].start = final_start;
- range[i].end = final_end;
- return nr_range;
+ /* clear it and add it back for further merge */
+ range[i].start = 0;
+ range[i].end = 0;
+ return add_range_with_merge(range, az, nr_range,
+ final_start, final_end);
}

/* Need to add it: */
--
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