[PATCH] percpu: fix per_cpu_ptr_to_phys() handling of non-page-aligned addresses.

[Eugene Surovegin <ebs@ebshome.net>]

per_cpu_ptr_to_phys() incorrectly rounds up its result for non-kmalloc case
to the page boundary, which is bogus for any non-page-aligned address.

This fixes the only in-tree user of this function - sysfs handler for
per-cpu 'crash_notes' physical address. The manifestation of this bug is
missing 'CORE' ELF notes in kdump.

Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
---
 mm/percpu.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 3bb810a..716eb4a 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1023,9 +1023,11 @@ phys_addr_t per_cpu_ptr_to_phys(void *addr)
 		if (!is_vmalloc_addr(addr))
 			return __pa(addr);
 		else
-			return page_to_phys(vmalloc_to_page(addr));
+			return page_to_phys(vmalloc_to_page(addr)) +
+			       offset_in_page(addr);
 	} else
-		return page_to_phys(pcpu_addr_to_page(addr));
+		return page_to_phys(pcpu_addr_to_page(addr)) +
+		       offset_in_page(addr);
 }
 
 /**
-- 
1.7.5.1

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