path: root/mm/percpu.c
diff options
authorVivek Goyal <vgoyal@redhat.com>2009-11-24 15:50:03 +0900
committerTejun Heo <tj@kernel.org>2009-11-25 21:49:22 +0900
commit3b034b0d084221596bf35c8d893e1d4d5477b9cc (patch)
treec3b9f33dc9fc748a9460036ae8647b16541a7547 /mm/percpu.c
parent833af8427be4b217b5bc522f61afdbd3f1d282c2 (diff)
percpu: Fix kdump failure if booted with percpu_alloc=page
o kdump functionality reserves a per cpu area at boot time and exports the physical address of that area to user space through sys interface. This area stores some dump related information like cpu register states etc at the time of crash. o We were assuming that per cpu area always come from linearly mapped meory region and using __pa() to determine physical address. With percpu_alloc=page, per cpu area can come from vmalloc region also and __pa() breaks. o This patch implments a new function to convert per cpu address to physical address. Before the patch, crash_notes addresses looked as follows. cpu0 60fffff49800 cpu1 60fffff60800 cpu2 60fffff77800 These are bogus phsyical addresses. After the patch, address are following. cpu0 13eb44000 cpu1 13eb43000 cpu2 13eb42000 cpu3 13eb41000 These look fine. I got 4G of memory and /proc/iomem tell me following. 100000000-13fffffff : System RAM tj: * added missing asm/io.h include reported by Stephen Rothwell * repositioned per_cpu_ptr_phys() in percpu.c and added comment. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Diffstat (limited to 'mm/percpu.c')
1 files changed, 22 insertions, 0 deletions
diff --git a/mm/percpu.c b/mm/percpu.c
index 5adfc268b40..008fbd9e6fa 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -74,6 +74,7 @@
#include <asm/cacheflush.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
+#include <asm/io.h>
#define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */
#define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */
@@ -1302,6 +1303,27 @@ void free_percpu(void *ptr)
+ * per_cpu_ptr_to_phys - convert translated percpu address to physical address
+ * @addr: the address to be converted to physical address
+ *
+ * Given @addr which is dereferenceable address obtained via one of
+ * percpu access macros, this function translates it into its physical
+ * address. The caller is responsible for ensuring @addr stays valid
+ * until this function finishes.
+ *
+ * The physical address for @addr.
+ */
+phys_addr_t per_cpu_ptr_to_phys(void *addr)
+ if ((unsigned long)addr < VMALLOC_START ||
+ (unsigned long)addr >= VMALLOC_END)
+ return __pa(addr);
+ else
+ return page_to_phys(vmalloc_to_page(addr));
static inline size_t pcpu_calc_fc_sizes(size_t static_size,
size_t reserved_size,
ssize_t *dyn_sizep)