From 8ce371f9846ef1e8b3cc8f6865766cb5c1f17e40 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 20 Mar 2017 12:26:55 +0100 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Tested-by: Borislav Petkov Cc: Sebastian Andrzej Siewior Cc: linux-mm@kvack.org Cc: wfg@linux.intel.com Cc: kernel test robot Cc: LKP Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net Signed-off-by: Thomas Gleixner --- include/linux/smp.h | 12 ++++++++++++ kernel/cpu.c | 6 ++++++ kernel/module.c | 6 +++++- mm/percpu.c | 5 ++++- 4 files changed, 27 insertions(+), 2 deletions(-) diff --git a/include/linux/smp.h b/include/linux/smp.h index 8e0cb7a0f836..68123c1fe549 100644 --- 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 f7c063239fa5..a795725774c5 100644 --- 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 5ef618133849..6d9988031c5b 100644 --- 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 7d3b728c0254..bd7416752819 100644 --- 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; } }