linux/arch/x86
Peter Zijlstra 602cae04c4 perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu()
intel_pmu_cpu_prepare() allocated memory for ->shared_regs among other
members of struct cpu_hw_events. This memory is released in
intel_pmu_cpu_dying() which is wrong. The counterpart of the
intel_pmu_cpu_prepare() callback is x86_pmu_dead_cpu().

Otherwise if the CPU fails on the UP path between CPUHP_PERF_X86_PREPARE
and CPUHP_AP_PERF_X86_STARTING then it won't release the memory but
allocate new memory on the next attempt to online the CPU (leaking the
old memory).
Also, if the CPU down path fails between CPUHP_AP_PERF_X86_STARTING and
CPUHP_PERF_X86_PREPARE then the CPU will go back online but never
allocate the memory that was released in x86_pmu_dying_cpu().

Make the memory allocation/free symmetrical in regard to the CPU hotplug
notifier by moving the deallocation to intel_pmu_cpu_dead().

This started in commit:

   a7e3ed1e47 ("perf: Add support for supplementary event registers").

In principle the bug was introduced in v2.6.39 (!), but it will almost
certainly not backport cleanly across the big CPU hotplug rewrite between v4.7-v4.15...

[ bigeasy: Added patch description. ]
[ mingo: Added backporting guidance. ]

Reported-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> # With developer hat on
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> # With maintainer hat on
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: jolsa@kernel.org
Cc: kan.liang@linux.intel.com
Cc: namhyung@kernel.org
Cc: <stable@vger.kernel.org>
Fixes: a7e3ed1e47 ("perf: Add support for supplementary event registers").
Link: https://lkml.kernel.org/r/20181219165350.6s3jvyxbibpvlhtq@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:44:51 +01:00
..
boot x86/boot/compressed/64: Set EFER.LME=1 in 32-bit trampoline before returning to long mode 2019-01-29 21:58:59 +01:00
configs PCI: consolidate PCI config entry in drivers/pci 2018-11-23 11:45:34 +09:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
entry x86/entry/64/compat: Fix stack switching for XEN PV 2019-01-18 00:39:33 +01:00
events perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu() 2019-02-04 08:44:51 +01:00
hyperv x86/hyper-v: Add HvFlushGuestAddressList hypercall support 2018-12-21 11:28:39 +01:00
ia32 Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
include Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-02-03 09:08:12 -08:00
kernel Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-02-03 09:08:12 -08:00
kvm cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM 2019-01-30 19:27:00 +01:00
lib x86: explicitly align IO accesses in memcpy_{to,from}io 2019-02-01 09:07:48 -08:00
math-emu Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
mm x86/fault: Fix sign-extend unintended sign extension 2019-01-29 21:58:59 +01:00
net bpf: Add bpf_line_info support 2018-12-09 13:54:38 -08:00
oprofile
pci pci-v4.21-changes 2019-01-05 17:57:34 -08:00
platform Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-12-26 18:42:51 -08:00
power mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
purgatory
ras
realmode
tools x86: Clean up 'sizeof x' => 'sizeof(x)' 2018-10-29 07:13:28 +01:00
um Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
video
xen xen: fixes for 5.0-rc3 2019-01-19 05:53:41 +12:00
.gitignore
Kbuild KVM: x86: Allow Qemu/KVM to use PVH entry point 2018-12-13 13:41:49 -05:00
Kconfig x86/resctrl: Avoid confusion over the new X86_RESCTRL config 2019-02-02 10:34:52 +01:00
Kconfig.cpu x86/cpu: Create Hygon Dhyana architecture support file 2018-09-27 16:14:05 +02:00
Kconfig.debug x86/kconfig: Remove redundant 'default n' lines from all x86 Kconfig's 2018-10-17 08:39:42 +02:00
Makefile jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
Makefile_32.cpu
Makefile.um x86, powerpc: Remove -funit-at-a-time compiler option entirely 2018-12-09 11:55:32 +01:00