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Commit 8ce371f9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

lockdep: Fix per-cpu static objects 



Since commit 383776fa ("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: 383776fa ("locking/lockdep: Handle statically initialized PER_CPU locks properly")
Reported-by: default avatarkernel test robot <fengguang.wu@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarBorislav 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent 56222b21

include/linux/smp.h

+12 −0
Original line number Diff line number Diff line
@@ -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 */



/*

kernel/cpu.c

+6 −0
Original line number Diff line number Diff line
@@ -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

}



/*

kernel/module.c

+5 −1
Original line number Diff line number Diff line
@@ -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;

			}

mm/percpu.c

+4 −1
Original line number Diff line number Diff line
@@ -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;

		}

	}