lockdep: Fix per-cpu static objects

Since commit 383776fa7527 ("locking/lockdep: Handle statically initialized
PER_CPU locks properly") we try to collapse per-cpu locks into a single
class by giving them all the same key. For this key we choose the canonical
address of the per-cpu object, which would be the offset into the per-cpu
area.

This has two problems:

 - there is a case where we run !0 lock->key through static_obj() and
   expect this to pass; it doesn't for canonical pointers.

 - 0 is a valid canonical address.

Cure both issues by redefining the canonical address as the address of the
per-cpu variable on the boot CPU.

Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at
all, track the boot CPU in a variable.

Fixes: 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly")
Reported-by: kernel test robot <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-mm@kvack.org
Cc: wfg@linux.intel.com
Cc: kernel test robot <fengguang.wu@intel.com>
Cc: LKP <lkp@01.org>
Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 8e0cb7a0f836faadd10ee917f8fe2c76d8965fa6..68123c1fe54918c051292eb5ba3427df09f31c2f 100644 (file)
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -120,6 +120,13 @@ extern unsigned int setup_max_cpus;
 extern void __init setup_nr_cpu_ids(void);
 extern void __init smp_init(void);
 
+extern int __boot_cpu_id;
+
+static inline int get_boot_cpu_id(void)
+{
+       return __boot_cpu_id;
+}
+
 #else /* !SMP */
 
 static inline void smp_send_stop(void) { }
@@ -158,6 +165,11 @@ static inline void smp_init(void) { up_late_init(); }
 static inline void smp_init(void) { }
 #endif
 
+static inline int get_boot_cpu_id(void)
+{
+       return 0;
+}
+
 #endif /* !SMP */
 
 /*

diff --git a/kernel/cpu.c b/kernel/cpu.c
index f7c063239fa5c74636922743ddb094052b9044c9..a795725774c5f9b91c41486647f130a6a1ef4742 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1125,6 +1125,8 @@ core_initcall(cpu_hotplug_pm_sync_init);
 
 #endif /* CONFIG_PM_SLEEP_SMP */
 
+int __boot_cpu_id;
+
 #endif /* CONFIG_SMP */
 
 /* Boot processor state steps */
@@ -1815,6 +1817,10 @@ void __init boot_cpu_init(void)
        set_cpu_active(cpu, true);
        set_cpu_present(cpu, true);
        set_cpu_possible(cpu, true);
+
+#ifdef CONFIG_SMP
+       __boot_cpu_id = cpu;
+#endif
 }
 
 /*

diff --git a/kernel/module.c b/kernel/module.c
index 5ef6181338494e25113afd4806c124db9896c6d0..6d9988031c5b3241e56a4c214d1c6690500e8187 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -682,8 +682,12 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
                        void *va = (void *)addr;
 
                        if (va >= start && va < start + mod->percpu_size) {
-                               if (can_addr)
+                               if (can_addr) {
                                        *can_addr = (unsigned long) (va - start);
+                                       *can_addr += (unsigned long)
+                                               per_cpu_ptr(mod->percpu,
+                                                           get_boot_cpu_id());
+                               }
                                preempt_enable();
                                return true;
                        }

diff --git a/mm/percpu.c b/mm/percpu.c
index 7d3b728c025456374a0739fd05dd41a8155663d8..bd74167528199c58a6b3ad4f4888446d48df26d0 100644 (file)
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1293,8 +1293,11 @@ bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
                void *va = (void *)addr;
 
                if (va >= start && va < start + static_size) {
-                       if (can_addr)
+                       if (can_addr) {
                                *can_addr = (unsigned long) (va - start);
+                               *can_addr += (unsigned long)
+                                       per_cpu_ptr(base, get_boot_cpu_id());
+                       }
                        return true;
                }
        }