1 files changed, 28 insertions, 3 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 46485e1b26fc..6470e7710231 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -229,8 +229,8 @@ static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
         return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
 }
 
-static unsigned long __maybe_unused pcpu_chunk_addr(struct pcpu_chunk *chunk,
-                                                unsigned int cpu, int page_idx)
+static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
+                                     unsigned int cpu, int page_idx)
 {
         return (unsigned long)chunk->base_addr + pcpu_unit_offsets[cpu] +
                 (page_idx << PAGE_SHIFT);
@@ -978,7 +978,32 @@ 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)) {
+        void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
+        bool in_first_chunk = false;
+        unsigned long first_start, first_end;
+        unsigned int cpu;
+
+        /*
+         * The following test on first_start/end isn't strictly
+         * necessary but will speed up lookups of addresses which
+         * aren't in the first chunk.
+         */
+        first_start = pcpu_chunk_addr(pcpu_first_chunk, pcpu_first_unit_cpu, 0);
+        first_end = pcpu_chunk_addr(pcpu_first_chunk, pcpu_last_unit_cpu,
+                                    pcpu_unit_pages);
+        if ((unsigned long)addr >= first_start &&
+            (unsigned long)addr < first_end) {
+                for_each_possible_cpu(cpu) {
+                        void *start = per_cpu_ptr(base, cpu);
+
+                        if (addr >= start && addr < start + pcpu_unit_size) {
+                                in_first_chunk = true;
+                                break;
+                        }
+                }
+        }
+
+        if (in_first_chunk) {
                 if ((unsigned long)addr < VMALLOC_START ||
                     (unsigned long)addr >= VMALLOC_END)
                         return __pa(addr);