Re: "BUG: using smp_processor_id() in preemptible" with KPTI on 4.14.11

[Greg Kroah-Hartman]

On Thu, Jan 04, 2018 at 11:20:29AM +0100, Thomas Zeitlhofer wrote:
> On Thu, Jan 04, 2018 at 02:59:06AM +0100, Thomas Zeitlhofer wrote:
> > Hello,
> > 
> > on an Ivybridge CPU, I get with 4.14.11:
> > 
> >    BUG: using smp_processor_id() in preemptible [00000000] code: ovsdb-server/4510
> >    caller is native_flush_tlb_single+0x57/0xc0
> >    CPU: 3 PID: 4510 Comm: ovsdb-server Not tainted 4.14.11-kvm-00434-gcd0b8eb84f5c #3
> >    Hardware name: MSI MS-7798/B75MA-P45 (MS-7798), BIOS V1.9 09/30/2013
> >    Call Trace:
> >     dump_stack+0x5c/0x86
> >     check_preemption_disabled+0xdd/0xe0
> >     native_flush_tlb_single+0x57/0xc0
> >     ? __set_pte_vaddr+0x2d/0x40
> >     __set_pte_vaddr+0x2d/0x40
> >     set_pte_vaddr+0x2f/0x40
> >     cea_set_pte+0x30/0x40
> >     ds_update_cea.constprop.4+0x4d/0x70
> >     reserve_ds_buffers+0x159/0x410
> >     ? wp_page_copy+0x36d/0x6a0
> >     x86_reserve_hardware+0x150/0x160
> >     x86_pmu_event_init+0x3e/0x1f0
> >     perf_try_init_event+0x69/0x80
> >     perf_event_alloc+0x652/0x740
> >     SyS_perf_event_open+0x3f6/0xd60
> >     do_syscall_64+0x5c/0x190
> >     entry_SYSCALL64_slow_path+0x25/0x25
> >    RIP: 0033:0x74a1d94580b9
> >    RSP: 002b:00007fff0c01d5d8 EFLAGS: 00000206 ORIG_RAX: 000000000000012a
> >    RAX: ffffffffffffffda RBX: 00007fff0c01d7b0 RCX: 000074a1d94580b9
> >    RDX: 00000000ffffffff RSI: 0000000000000000 RDI: 00007fff0c01d5e0
> >    RBP: 0000000000000000 R08: 0000000000000000 R09: 0000007000000000
> >    R10: 00000000ffffffff R11: 0000000000000206 R12: 0000000000000008
> >    R13: 0000000000000000 R14: 00007fff0c01d790 R15: 00005df43a799600
> > 
> > This does not show up when booting with pti=off.
> > 
> > Maybe it is related to the issue that is fixed for the upcoming 4.4.110
> > release by https://lkml.org/lkml/2018/1/3/692

I don't understand this link.  The 4.4 and 4.9 backports are much
different than the 4.14 tree.

> JFYI, the very same kernel does not show this issue on a Haswell CPU.

I have now queued up a bunch of patches that are in Linus's tree, can
you test these out as well:
	https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-4.14

thanks,

greg k-h