linux-kernel - Re: per_cpu_ptr_to_phys() failure on UV x86

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Date:	Thu, 17 Jun 2010 19:35:16 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Cliff Wickman <cpw@....com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: per_cpu_ptr_to_phys() failure on UV x86_64

On 06/17/2010 07:08 PM, Tejun Heo wrote:
> (scratching head...) So, that means it's given an address for which
> !pcpu_addr_in_first_chunk() but outside of vmalloc area.  Strange.
> I'll find out what's going on.

Does the following patch work?  The original patch assumed that @addr
would be the address of the base cpu which isn't true.  I only compile
tested the patch so it might be broken (sorry, I gotta go somewhere
now) but this should be the right direction.

Thanks.

diff --git a/mm/percpu.c b/mm/percpu.c
index 46485e1..8956155 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -978,14 +978,23 @@ bool is_kernel_percpu_address(unsigned long addr)
  */
 phys_addr_t per_cpu_ptr_to_phys(void *addr)
 {
-	if (pcpu_addr_in_first_chunk(addr)) {
-		if ((unsigned long)addr < VMALLOC_START ||
-		    (unsigned long)addr >= VMALLOC_END)
-			return __pa(addr);
-		else
-			return page_to_phys(vmalloc_to_page(addr));
-	} else
-		return page_to_phys(pcpu_addr_to_page(addr));
+	void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
+	unsigned int cpu;
+
+	for_each_possible_cpu(cpu) {
+		void *start = per_cpu_ptr(base, cpu);
+
+		if (addr >= start && addr < start + pcpu_unit_size) {
+			/* in the first chunk */
+			if ((unsigned long)addr < VMALLOC_START ||
+			    (unsigned long)addr >= VMALLOC_END)
+				return __pa(addr);
+			else
+				return page_to_phys(vmalloc_to_page(addr));
+		}
+	}
+	/* in one of the other chunks */
+	return page_to_phys(pcpu_addr_to_page(addr));
 }

 static inline size_t pcpu_calc_fc_sizes(size_t static_size,


-- 
tejun
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