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Matt Fleming 2c534c0da0 perf/x86/intel/cqm: Return cached counter value from IRQ context 
Peter reported the following potential crash which I was able to
reproduce with his test program,

[  148.765788] ------------[ cut here ]------------
[  148.765796] WARNING: CPU: 34 PID: 2840 at kernel/smp.c:417 smp_call_function_many+0xb6/0x260()
[  148.765797] Modules linked in:
[  148.765800] CPU: 34 PID: 2840 Comm: perf Not tainted 4.2.0-rc1+ #4
[  148.765803]  ffffffff81cdc398 ffff88085f105950 ffffffff818bdfd5 0000000000000007
[  148.765805]  0000000000000000 ffff88085f105990 ffffffff810e413a 0000000000000000
[  148.765807]  ffffffff82301080 0000000000000022 ffffffff8107f640 ffffffff8107f640
[  148.765809] Call Trace:
[  148.765810]  <NMI>  [<ffffffff818bdfd5>] dump_stack+0x45/0x57
[  148.765818]  [<ffffffff810e413a>] warn_slowpath_common+0x8a/0xc0
[  148.765822]  [<ffffffff8107f640>] ? intel_cqm_stable+0x60/0x60
[  148.765824]  [<ffffffff8107f640>] ? intel_cqm_stable+0x60/0x60
[  148.765825]  [<ffffffff810e422a>] warn_slowpath_null+0x1a/0x20
[  148.765827]  [<ffffffff811613f6>] smp_call_function_many+0xb6/0x260
[  148.765829]  [<ffffffff8107f640>] ? intel_cqm_stable+0x60/0x60
[  148.765831]  [<ffffffff81161748>] on_each_cpu_mask+0x28/0x60
[  148.765832]  [<ffffffff8107f6ef>] intel_cqm_event_count+0x7f/0xe0
[  148.765836]  [<ffffffff811cdd35>] perf_output_read+0x2a5/0x400
[  148.765839]  [<ffffffff811d2e5a>] perf_output_sample+0x31a/0x590
[  148.765840]  [<ffffffff811d333d>] ? perf_prepare_sample+0x26d/0x380
[  148.765841]  [<ffffffff811d3497>] perf_event_output+0x47/0x60
[  148.765843]  [<ffffffff811d36c5>] __perf_event_overflow+0x215/0x240
[  148.765844]  [<ffffffff811d4124>] perf_event_overflow+0x14/0x20
[  148.765847]  [<ffffffff8107e7f4>] intel_pmu_handle_irq+0x1d4/0x440
[  148.765849]  [<ffffffff811d07a6>] ? __perf_event_task_sched_in+0x36/0xa0
[  148.765853]  [<ffffffff81219bad>] ? vunmap_page_range+0x19d/0x2f0
[  148.765854]  [<ffffffff81219d11>] ? unmap_kernel_range_noflush+0x11/0x20
[  148.765859]  [<ffffffff814ce6fe>] ? ghes_copy_tofrom_phys+0x11e/0x2a0
[  148.765863]  [<ffffffff8109e5db>] ? native_apic_msr_write+0x2b/0x30
[  148.765865]  [<ffffffff8109e44d>] ? x2apic_send_IPI_self+0x1d/0x20
[  148.765869]  [<ffffffff81065135>] ? arch_irq_work_raise+0x35/0x40
[  148.765872]  [<ffffffff811c8d86>] ? irq_work_queue+0x66/0x80
[  148.765875]  [<ffffffff81075306>] perf_event_nmi_handler+0x26/0x40
[  148.765877]  [<ffffffff81063ed9>] nmi_handle+0x79/0x100
[  148.765879]  [<ffffffff81064422>] default_do_nmi+0x42/0x100
[  148.765880]  [<ffffffff81064563>] do_nmi+0x83/0xb0
[  148.765884]  [<ffffffff818c7c0f>] end_repeat_nmi+0x1e/0x2e
[  148.765886]  [<ffffffff811d07a6>] ? __perf_event_task_sched_in+0x36/0xa0
[  148.765888]  [<ffffffff811d07a6>] ? __perf_event_task_sched_in+0x36/0xa0
[  148.765890]  [<ffffffff811d07a6>] ? __perf_event_task_sched_in+0x36/0xa0
[  148.765891]  <<EOE>>  [<ffffffff8110ab66>] finish_task_switch+0x156/0x210
[  148.765898]  [<ffffffff818c1671>] __schedule+0x341/0x920
[  148.765899]  [<ffffffff818c1c87>] schedule+0x37/0x80
[  148.765903]  [<ffffffff810ae1af>] ? do_page_fault+0x2f/0x80
[  148.765905]  [<ffffffff818c1f4a>] schedule_user+0x1a/0x50
[  148.765907]  [<ffffffff818c666c>] retint_careful+0x14/0x32
[  148.765908] ---[ end trace e33ff2be78e14901 ]---

The CQM task events are not safe to be called from within interrupt
context because they require performing an IPI to read the counter value
on all sockets. And performing IPIs from within IRQ context is a
"no-no".

Make do with the last read counter value currently event in
event->count when we're invoked in this context.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikas Shivappa <vikas.shivappa@intel.com>
Cc: Kanaka Juvva <kanaka.d.juvva@intel.com>
Cc: Will Auld <will.auld@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1437490509-15373-1-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 		2015-07-26 10:22:29 +02:00
..
alpha mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
arc mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
arm MMC core: 2015-07-24 16:43:16 -07:00
arm64 ARM64/irq: Use access helper irq_data_get_affinity_mask() 2015-07-22 10:57:09 +01:00
avr32 AVR32/time: Migrate to new 'set-state' interface 2015-07-20 12:19:10 +02:00
blackfin mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
c6x mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
cris mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
frv mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
h8300 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
hexagon mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
ia64 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
m32r m32r: Add ioreadXX/iowriteXX big-endian mmio accessors 2015-07-23 18:08:28 -07:00
m68k mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
metag mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
microblaze mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
mips Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-07-19 14:12:22 -07:00
mn10300 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
nios2 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
openrisc mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
parisc parisc: mm: Fix a memory leak related to pmd not attached to the pgd 2015-07-19 08:56:14 +02:00
powerpc powerpc/perf/24x7: Fix lockdep warning 2015-07-08 15:18:04 +10:00
s390 s390: adapt entry.S to the move of thread_struct 2015-07-20 13:22:18 +02:00
score mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
sh mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
sparc mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
tile tile: use free_bootmem_late() for initrd 2015-07-23 14:11:09 -04:00
um mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
unicore32 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
x86 perf/x86/intel/cqm: Return cached counter value from IRQ context 2015-07-26 10:22:29 +02:00
xtensa mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
.gitignore
…
Kconfig x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86 2015-07-18 03:42:51 +02:00