Commit-ID:  94cc60b72f99006f6f2b9b5b7317805d6e5abddb
Gitweb:     https://git.kernel.org/tip/94cc60b72f99006f6f2b9b5b7317805d6e5abddb
Author:     Dan Williams <[email protected]>
AuthorDate: Tue, 3 Jul 2018 14:00:57 -0700
Committer:  Ingo Molnar <[email protected]>
CommitDate: Wed, 4 Jul 2018 18:12:20 +0200

x86/numa_emulation: Fix uniform size build failure

The calculation of a uniform numa-node size attempted to perform
division with a 64-bit diviser leading to the following failure on
32-bit:

    arch/x86/mm/numa_emulation.o: In function 
`split_nodes_size_interleave_uniform':
    arch/x86/mm/numa_emulation.c:239: undefined reference to `__udivdi3'

Convert the implementation to do the division in terms of pages and then
shift the result back to an absolute physical address.

Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: [email protected]
Fixes: 93e738834fcc ("x86/numa_emulation: Introduce uniform split capability")
Link: 
http://lkml.kernel.org/r/153065162801.12250.4860144566061573514.st...@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <[email protected]>
---
 arch/x86/mm/numa_emulation.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 039db00541b7..cc7523e45926 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -198,6 +198,14 @@ static u64 __init find_end_of_node(u64 start, u64 
max_addr, u64 size)
        return end;
 }
 
+static u64 uniform_size(u64 max_addr, u64 base, int nr_nodes)
+{
+       unsigned long max_pfn = PHYS_PFN(max_addr);
+       unsigned long base_pfn = PHYS_PFN(base);
+
+       return PFN_PHYS((max_pfn - base_pfn) / nr_nodes);
+}
+
 /*
  * Sets up fake nodes of `size' interleaved over physical nodes ranging from
  * `addr' to `max_addr'.
@@ -236,7 +244,7 @@ static int __init 
split_nodes_size_interleave_uniform(struct numa_meminfo *ei,
        }
 
        if (uniform) {
-               min_size = (max_addr - addr) / nr_nodes;
+               min_size = uniform_size(max_addr, addr, nr_nodes);
                size = min_size;
        } else {
                /*

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