Messages in this thread Patch in this message | | | Date | Fri, 27 Jun 2014 10:13:59 -0700 | From | "Paul E. McKenney" <> | Subject | Re: rcu: NULL ptr deref on boot |
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On Fri, Jun 27, 2014 at 12:48:11PM -0400, Sasha Levin wrote: > Hi Paul, > > I've noticed the following on boot with the latest -next kernel: > > [ 0.000000] WARNING: CPU: 0 PID: 0 at arch/x86/kernel/cpu/common.c:1439 warn_pre_alternatives+0x1e/0x20() > [ 0.000000] You're using static_cpu_has before alternatives have run! > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.16.0-rc2-next-20140627-sasha-00023-g5d10814-dirty #734 > [ 0.000000] 0000000000000009 ffffffff9d003c48 ffffffff9b525423 0000000000000002 > [ 0.000000] ffffffff9d003c98 ffffffff9d003c88 ffffffff98168aec ffffffff9d003d58 > [ 0.000000] 0000000000000000 ffffffff9d003e78 0000000000000000 0000000000000002 > [ 0.000000] Call Trace: > [ 0.000000] dump_stack (lib/dump_stack.c:52) > [ 0.000000] warn_slowpath_common (kernel/panic.c:431) > [ 0.000000] warn_slowpath_fmt (kernel/panic.c:446) > [ 0.000000] ? irq_return (arch/x86/kernel/entry_64.S:842) > [ 0.000000] warn_pre_alternatives (arch/x86/kernel/cpu/common.c:1440) > [ 0.000000] __do_page_fault (./arch/x86/include/asm/cpufeature.h:423 arch/x86/mm/fault.c:1022 arch/x86/mm/fault.c:1112) > [ 0.000000] ? trace_hardirqs_off_caller (kernel/locking/lockdep.c:2638 (discriminator 2)) > [ 0.000000] ? trace_hardirqs_off (kernel/locking/lockdep.c:2645) > [ 0.000000] ? __slab_alloc (mm/slub.c:2364 (discriminator 1)) > [ 0.000000] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63) > [ 0.000000] ? trace_hardirqs_off_caller (kernel/locking/lockdep.c:2638 (discriminator 2)) > [ 0.000000] ? error_sti (arch/x86/kernel/entry_64.S:1419) > [ 0.000000] trace_do_page_fault (arch/x86/mm/fault.c:1313 include/linux/jump_label.h:115 include/linux/context_tracking_state.h:27 include/linux/context_tracking.h:45 arch/x86/mm/fault.c:1314) > [ 0.000000] do_async_page_fault (arch/x86/kernel/kvm.c:264) > [ 0.000000] async_page_fault (arch/x86/kernel/entry_64.S:1322) > [ 0.000000] ? tick_nohz_init (include/linux/bitmap.h:165 include/linux/cpumask.h:333 kernel/time/tick-sched.c:344 kernel/time/tick-sched.c:356) > [ 0.000000] ? tick_nohz_init (include/linux/bitmap.h:164 include/linux/cpumask.h:333 kernel/time/tick-sched.c:344 kernel/time/tick-sched.c:356) > [ 0.000000] start_kernel (init/main.c:581) > [ 0.000000] ? set_init_arg (init/main.c:281) > [ 0.000000] ? early_idt_handlers (arch/x86/kernel/head_64.S:340) > [ 0.000000] x86_64_start_reservations (arch/x86/kernel/head64.c:194) > [ 0.000000] x86_64_start_kernel (arch/x86/kernel/head64.c:183) > [ 0.000000] ---[ end trace 4d5ff9f2f68c4233 ]--- > [ 0.000000] BUG: unable to handle kernel NULL pointer dereference at (null) > [ 0.000000] IP: tick_nohz_init (include/linux/bitmap.h:165 include/linux/cpumask.h:333 kernel/time/tick-sched.c:344 kernel/time/tick-sched.c:356) > [ 0.000000] PGD 0 > [ 0.000000] Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 3.16.0-rc2-next-20140627-sasha-00023-g5d10814-dirty #734 > [ 0.000000] task: ffffffff9d0354c0 ti: ffffffff9d000000 task.ti: ffffffff9d000000 > [ 0.000000] RIP: tick_nohz_init (include/linux/bitmap.h:165 include/linux/cpumask.h:333 kernel/time/tick-sched.c:344 kernel/time/tick-sched.c:356) > [ 0.000000] RSP: 0000:ffffffff9d003f28 EFLAGS: 00010002 > [ 0.000000] RAX: 0000000000000000 RBX: ffff88003684d480 RCX: 0000000000000008 > [ 0.000000] RDX: 0000000000000014 RSI: ffff88003684d480 RDI: 0000000000000000 > [ 0.000000] RBP: ffffffff9d003f38 R08: ffff88003684d480 R09: ffff88003684d480 > [ 0.000000] R10: ffff88003684d480 R11: 0000000000000001 R12: ffffffff9e5fd020 > [ 0.000000] R13: ffff88070282ca00 R14: ffffffff9e607ae0 R15: 00000000000146f0 > [ 0.000000] FS: 0000000000000000(0000) GS:ffff880036e00000(0000) knlGS:0000000000000000 > [ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 0.000000] CR2: 0000000000000000 CR3: 000000001d02e000 CR4: 00000000000006b0 > [ 0.000000] Stack: > [ 0.000000] ffffffffffffffff ffffffff9e5fd020 ffffffff9d003f88 ffffffff9e4c9f09 > [ 0.000000] ffffffff9e4c98fd 00000000000146f0 ffffffff9d003f78 ffffffff9e607ae0 > [ 0.000000] 0000000000000020 ffffffff9e4c9117 00000000ffffffff 0000ffffffff9e4c > [ 0.000000] Call Trace: > [ 0.000000] start_kernel (init/main.c:581) > [ 0.000000] ? set_init_arg (init/main.c:281) > [ 0.000000] ? early_idt_handlers (arch/x86/kernel/head_64.S:340) > [ 0.000000] x86_64_start_reservations (arch/x86/kernel/head64.c:194) > [ 0.000000] x86_64_start_kernel (arch/x86/kernel/head64.c:183) > [ 0.000000] Code: e8 d0 84 66 fa 89 c7 48 89 de e8 b0 46 02 fd 48 63 0d 4f 91 dd ff 31 c0 48 8b 3d 5e 1f 1c 01 48 83 c1 3f 48 c1 f9 03 48 83 e1 f8 <f3> aa 48 8b 1d 49 1f 1c 01 e8 9c 84 66 fa 89 c7 e8 25 3c d1 f9 > All code > ======== > 0: e8 d0 84 66 fa callq 0xfffffffffa6684d5 > 5: 89 c7 mov %eax,%edi > 7: 48 89 de mov %rbx,%rsi > a: e8 b0 46 02 fd callq 0xfffffffffd0246bf > f: 48 63 0d 4f 91 dd ff movslq -0x226eb1(%rip),%rcx # 0xffffffffffdd9165 > 16: 31 c0 xor %eax,%eax > 18: 48 8b 3d 5e 1f 1c 01 mov 0x11c1f5e(%rip),%rdi # 0x11c1f7d > 1f: 48 83 c1 3f add $0x3f,%rcx > 23: 48 c1 f9 03 sar $0x3,%rcx > 27: 48 83 e1 f8 and $0xfffffffffffffff8,%rcx > 2b: f3 aa rep stos %al,%es:*(%rdi) <-- trapping instruction > 2d: 48 8b 1d 49 1f 1c 01 mov 0x11c1f49(%rip),%rbx # 0x11c1f7d > 34: e8 9c 84 66 fa callq 0xfffffffffa6684d5 > 39: 89 c7 mov %eax,%edi > 3b: e8 25 3c d1 f9 callq 0xfffffffff9d13c65 > ... > > Code starting with the faulting instruction > =========================================== > 0: f3 aa rep stos %al,%es:(%rdi) > 2: 48 8b 1d 49 1f 1c 01 mov 0x11c1f49(%rip),%rbx # 0x11c1f52 > 9: e8 9c 84 66 fa callq 0xfffffffffa6684aa > e: 89 c7 mov %eax,%edi > 10: e8 25 3c d1 f9 callq 0xfffffffff9d13c3a > ... > [ 0.000000] RIP tick_nohz_init (include/linux/bitmap.h:165 include/linux/cpumask.h:333 kernel/time/tick-sched.c:344 kernel/time/tick-sched.c:356) > [ 0.000000] RSP <ffffffff9d003f28> > [ 0.000000] CR2: 0000000000000000 > > Bisection pointed me to "rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs".
Yikes! tick_nohz_full_mask is allocated not in one place, but two!
Does the following patch help?
Thanx, Paul
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diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 07ae1cc39063..e023134d63a1 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -336,6 +336,10 @@ static int tick_nohz_init_all(void) pr_err("NO_HZ: Can't allocate full dynticks cpumask\n"); return err; } + if (!alloc_cpumask_var(&tick_nohz_not_full_mask, GFP_KERNEL)) { + pr_err("NO_HZ: Can't allocate not-full dynticks cpumask\n"); + return err; + } err = 0; cpumask_setall(tick_nohz_full_mask); cpumask_clear_cpu(smp_processor_id(), tick_nohz_full_mask);
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