Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752472AbdGGIeQ (ORCPT ); Fri, 7 Jul 2017 04:34:16 -0400 Received: from mail-wr0-f181.google.com ([209.85.128.181]:35310 "EHLO mail-wr0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751782AbdGGIeO (ORCPT ); Fri, 7 Jul 2017 04:34:14 -0400 From: Alexander Potapenko To: dvyukov@google.com, kcc@google.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH] slub: make sure struct kmem_cache_node is initialized before publication Date: Fri, 7 Jul 2017 10:34:08 +0200 Message-Id: <20170707083408.40410-1-glider@google.com> X-Mailer: git-send-email 2.13.2.725.g09c95d1e9-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5450 Lines: 123 According to KMSAN (see the report below) it's possible that unfreeze_partials() accesses &n->list_lock before it's being initialized. The initialization normally happens in init_kmem_cache_node() when it's called from init_kmem_cache_nodes(), but only after the struct kmem_cache_node is published. To avoid what appears to be a data race, we need to publish the struct after it has been initialized. KMSAN (https://github.com/google/kmsan) report is as follows: ================================================================== BUG: KMSAN: use of uninitialized memory in queued_spin_lock_slowpath+0xa55/0xaf0 kernel/locking/qspinlock.c:478 CPU: 1 PID: 5021 Comm: modprobe Not tainted 4.11.0-rc5+ #2876 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x172/0x1c0 lib/dump_stack.c:52 kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:927 __msan_warning_32+0x61/0xb0 mm/kmsan/kmsan_instr.c:469 queued_spin_lock_slowpath+0xa55/0xaf0 kernel/locking/qspinlock.c:478 queued_spin_lock include/asm-generic/qspinlock.h:103 [inline] do_raw_spin_lock include/linux/spinlock.h:148 [inline] __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_lock+0x73/0x80 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:299 [inline] unfreeze_partials+0x6d/0x210 mm/slub.c:2181 put_cpu_partial mm/slub.c:2255 [inline] __slab_free mm/slub.c:2894 [inline] do_slab_free mm/slub.c:2990 [inline] slab_free mm/slub.c:3005 [inline] kmem_cache_free+0x39d/0x5b0 mm/slub.c:3020 free_task_struct kernel/fork.c:158 [inline] free_task kernel/fork.c:370 [inline] __put_task_struct+0x7eb/0x880 kernel/fork.c:407 put_task_struct include/linux/sched/task.h:94 [inline] delayed_put_task_struct+0x271/0x2b0 kernel/exit.c:181 __rcu_reclaim kernel/rcu/rcu.h:118 [inline] rcu_do_batch kernel/rcu/tree.c:2879 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:3142 [inline] __rcu_process_callbacks kernel/rcu/tree.c:3109 [inline] rcu_process_callbacks+0x1f10/0x2b50 kernel/rcu/tree.c:3126 __do_softirq+0x485/0x942 kernel/softirq.c:284 invoke_softirq kernel/softirq.c:364 [inline] irq_exit+0x1fa/0x230 kernel/softirq.c:405 exiting_irq+0xe/0x10 arch/x86/include/asm/apic.h:657 smp_apic_timer_interrupt+0x5a/0x80 arch/x86/kernel/apic/apic.c:966 apic_timer_interrupt+0x86/0x90 arch/x86/entry/entry_64.S:489 RIP: 0010:native_restore_fl arch/x86/include/asm/irqflags.h:36 [inline] RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:77 [inline] RIP: 0010:__msan_poison_alloca+0xed/0x120 mm/kmsan/kmsan_instr.c:440 RSP: 0018:ffff880023d6f7b8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: 0000000000000246 RBX: ffff88001ebf8000 RCX: 0000000000000002 RDX: 0000000000000001 RSI: ffff880000000000 RDI: ffffea0000b332f0 RBP: ffff880023d6f838 R08: 0000000000000884 R09: 0000000000000004 R10: 0000160000000000 R11: 0000000000000000 R12: ffffffff85ab5df0 R13: ffff880023d6f885 R14: 0000000000000001 R15: ffffffff81ae424d page_remove_rmap+0x9d/0xd80 mm/rmap.c:1256 zap_pte_range mm/memory.c:1237 [inline] zap_pmd_range mm/memory.c:1318 [inline] zap_pud_range mm/memory.c:1347 [inline] zap_p4d_range mm/memory.c:1368 [inline] unmap_page_range+0x28fd/0x34a0 mm/memory.c:1389 unmap_single_vma+0x354/0x4b0 mm/memory.c:1434 unmap_vmas+0x192/0x2a0 mm/memory.c:1464 unmap_region+0x375/0x4c0 mm/mmap.c:2464 do_munmap+0x1a39/0x2360 mm/mmap.c:2669 vm_munmap mm/mmap.c:2688 [inline] SYSC_munmap+0x13d/0x1a0 mm/mmap.c:2698 SyS_munmap+0x47/0x70 mm/mmap.c:2695 entry_SYSCALL_64_fastpath+0x13/0x94 RIP: 0033:0x7fb3c34f0d37 RSP: 002b:00007ffd44afc268 EFLAGS: 00000206 ORIG_RAX: 000000000000000b RAX: ffffffffffffffda RBX: 0000563670927260 RCX: 00007fb3c34f0d37 RDX: 0000000000000000 RSI: 0000000000001000 RDI: 00007fb3c3bd5000 RBP: 0000000000000000 R08: 00007fb3c3bd1700 R09: 00007ffd44afc3c8 R10: 0000000000000000 R11: 0000000000000206 R12: 00000000ffffffff R13: 0000563670927110 R14: 0000563670927210 R15: 00007ffd44afc4f0 origin: save_stack_trace+0x37/0x40 arch/x86/kernel/stacktrace.c:59 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:302 [inline] kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:198 kmsan_kmalloc+0x7f/0xe0 mm/kmsan/kmsan.c:337 kmsan_post_alloc_hook+0x10/0x20 mm/kmsan/kmsan.c:350 slab_post_alloc_hook mm/slab.h:459 [inline] slab_alloc_node mm/slub.c:2747 [inline] kmem_cache_alloc_node+0x150/0x210 mm/slub.c:2788 init_kmem_cache_nodes mm/slub.c:3430 [inline] kmem_cache_open mm/slub.c:3649 [inline] __kmem_cache_create+0x13e/0x5f0 mm/slub.c:4290 create_cache mm/slab_common.c:382 [inline] kmem_cache_create+0x186/0x220 mm/slab_common.c:467 fork_init+0x7e/0x430 kernel/fork.c:451 start_kernel+0x499/0x580 init/main.c:654 x86_64_start_reservations arch/x86/kernel/head64.c:196 [inline] x86_64_start_kernel+0x6cc/0x700 arch/x86/kernel/head64.c:177 verify_cpu+0x0/0xfc ================================================================== Signed-off-by: Alexander Potapenko --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 1d3f9835f4ea..481e523bb30d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3389,8 +3389,8 @@ static int init_kmem_cache_nodes(struct kmem_cache *s) return 0; } - s->node[node] = n; init_kmem_cache_node(n); + s->node[node] = n; } return 1; } -- 2.13.2.725.g09c95d1e9-goog