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SubjectRe: "BUG: using smp_processor_id() in preemptible" with KPTI on 4.14.11
On Sun, Jan 07, 2018 at 09:17:18AM +0100, Greg Kroah-Hartman wrote:
> On Sat, Jan 06, 2018 at 10:38:38PM +0100, Thomas Zeitlhofer wrote:
> > On Thu, Jan 04, 2018 at 07:38:00PM +0100, Thomas Zeitlhofer wrote:
> > > On Thu, Jan 04, 2018 at 06:07:12PM +0100, Peter Zijlstra wrote:
> > > > On Thu, Jan 04, 2018 at 04:37:24PM +0100, Thomas Gleixner wrote:
> > > > > > Yes:
> > > > > >
> > > > > > BUG: using smp_processor_id() in preemptible [00000000] code: ovsdb-server/4498
> > > > > > caller is native_flush_tlb_single+0x57/0xc0
> > > > > > CPU: 2 PID: 4498 Comm: ovsdb-server Not tainted 4.15.0-rc6-kvm-00423-gea1908c252eb #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+0x370/0x6c0
> > > > > > 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: 0033:0x72bff0a3c0b9
> > > > > > RSP: 002b:00007ffed11c2f18 EFLAGS: 00000206 ORIG_RAX: 000000000000012a
> > > > > > RAX: ffffffffffffffda RBX: 00007ffed11c30f0 RCX: 000072bff0a3c0b9
> > > > > > RDX: 00000000ffffffff RSI: 0000000000000000 RDI: 00007ffed11c2f20
> > > > > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000007000000000
> > > > > > R10: 00000000ffffffff R11: 0000000000000206 R12: 0000000000000008
> > > > > > R13: 0000000000000000 R14: 00007ffed11c30d0 R15: 000060986ecfb600
> > > >
> > > > Fun, so set_pte_vaddr() and the whole cpu_entry_area are supposed to be
> > > > per CPU. But the DS crud does cross CPU updates of those tables.
> > > >
> > > > So we need some additional fun and games..
> > > >
> > > > How's the below?
> > > [...]
> > >
> > > Looks good - I have successfully tested it on top of 4.14.11 and
> > > 4.15-rc6. In both cases, the error message is gone when this patch is
> > > applied.
> >
> > While solving the previous problem, this patch also introduces new "fun
> > and games"...
> >
> > Now, terminating a systemd-nspawn container, reliably crashes the host
> > (so far tested only on Haswell, if that matters). Once, I was able to
> > capture the following trace:
>
> Is this also reproducable on Linus's tree right now?

It is reproducible with this patch on top of 4.15-rc6 (might be able to
test Linus's current tree later that day).

Thanks,

Thomas

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