From: Nicholas Piggin <npiggin@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: alexander.levin@verizon.com,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"stable\@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH AUTOSEL for 3.18 36/40] powerpc/xmon: Avoid tripping SMP hardlockup watchdog
Date: Sat, 3 Feb 2018 15:58:22 +1000 [thread overview]
Message-ID: <20180203155822.01e2e34b@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <87h8r47yl1.fsf@concordia.ellerman.id.au>
On Tue, 30 Jan 2018 15:35:54 +1100
Michael Ellerman <mpe@ellerman.id.au> wrote:
> alexander.levin@verizon.com writes:
>
> > On Thu, Dec 14, 2017 at 12:10:39AM +1100, Michael Ellerman wrote:
> >>alexander.levin@verizon.com writes:
> >>
> >>> From: Nicholas Piggin <npiggin@gmail.com>
> >>>
> >>> [ Upstream commit 064996d62a33ffe10264b5af5dca92d54f60f806 ]
> >>>
> >>> The SMP hardlockup watchdog cross-checks other CPUs for lockups, which
> >>> causes xmon headaches because it's assuming interrupts hard disabled
> >>> means no watchdog troubles. Try to improve that by calling
> >>> touch_nmi_watchdog() in obvious places where secondaries are spinning.
> >>>
> >>> Also annotate these spin loops with spin_begin/end calls.
> >>
> >>These macros didn't exist until 4.13, and haven't been backported AFAIK.
> >
> > But the touch_nmi_watchdog() bits are something we want in stable, right?
>
> I don't think you need them unless you've also back ported
> arch/powerpc/kernel/watchdog.c, which I don't think you have.
>
> Maybe Nick can confirm?
I'm not 100% sure. The CPUs only check themselves for lockups. They will
blow their threshold when in xmon, but when they come out of xmon, I think
by a quirk of our local_irq_enable() implementation that actually checks
timers explicitly and runs them first before re-enabling hard interrupts,
then our heartbeat starts up again just before the perf interrupt would
come in to report the lockup.
I think.
Given that we've had no reports of misbehaviour of the old perf watchdog,
I would say you can skip the backport.
Thanks,
Nick
next prev parent reply other threads:[~2018-02-03 5:58 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-13 1:59 [PATCH AUTOSEL for 3.18 01/40] ALSA: hda - add support for docking station for HP 820 G2 alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 03/40] r8152: fix the list rx_done may be used without initialization alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 02/40] cpuidle: Validate cpu_dev in cpuidle_add_sysfs() alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 05/40] net: qmi_wwan: Add USB IDs for MDM6600 modem on Motorola Droid 4 alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 07/40] usb: gadget: udc: remove pointer dereference after free alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 04/40] crypto: deadlock between crypto_alg_sem/rtnl_mutex/genl_mutex alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 06/40] usb: gadget: f_uvc: Sanity check wMaxPacketSize for SuperSpeed alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 11/40] KVM: x86: correct async page present tracepoint alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 10/40] scsi: lpfc: Fix PT2PT PRLI reject alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 09/40] netfilter: nfnl_cthelper: Fix memory leak alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 08/40] netfilter: nfnl_cthelper: fix runtime expectation policy updates alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 13/40] hwmon: (asus_atk0110) fix uninitialized data access alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 12/40] ARM: dts: ti: fix PCI bus dtc warnings alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 14/40] i2c: mux: pca954x: Add missing pca9546 definition to chip_desc alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 15/40] HID: xinmo: fix for out of range for THT 2P arcade controller alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 19/40] irda: vlsi_ir: fix check for DMA mapping errors alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 17/40] net: Do not allow negative values for busy_read and busy_poll sysctl interfaces alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 16/40] s390/qeth: no ETH header for outbound AF_IUCV alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 18/40] i40e: Do not enable NAPI on q_vectors that have no rings alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 21/40] netfilter: nf_nat_snmp: Fix panic when snmp_trap_helper fails to register alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 23/40] isdn: kcapi: avoid uninitialized data alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 22/40] ARM: dts: am335x-evmsk: adjust mmc2 param to allow suspend alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 20/40] netfilter: nfnl_cthelper: fix a race when walk the nf_ct_helper_hash table alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 25/40] ARM: dma-mapping: disallow dma_get_sgtable() for non-kernel managed memory alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 27/40] backlight: pwm_bl: Fix overflow condition alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 26/40] cpuidle: powernv: Pass correct drv->cpumask for registration alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 24/40] xhci: plat: Register shutdown for xhci_plat alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 30/40] PCI: Avoid bus reset if bridge itself is broken alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 29/40] net: phy: at803x: Change error to EINVAL for invalid MAC alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 31/40] scsi: cxgb4i: fix Tx skb leak alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 28/40] crypto: crypto4xx - increase context and scatter ring buffer elements alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 35/40] percpu: don't forget to free the temporary struct pcpu_alloc_info alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 32/40] PCI: Create SR-IOV virtfn/physfn links before attaching driver alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 34/40] PCI/AER: Report non-fatal errors only to the affected endpoint alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 33/40] igb: check memory allocation failure alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 36/40] powerpc/xmon: Avoid tripping SMP hardlockup watchdog alexander.levin
2017-12-13 13:10 ` Michael Ellerman
2017-12-13 13:44 ` alexander.levin
2018-01-30 4:35 ` Michael Ellerman
2018-02-03 5:58 ` Nicholas Piggin [this message]
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 38/40] scsi: lpfc: PLOGI failures during NPIV testing alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 39/40] fm10k: ensure we process SM mbx when processing VF mbx alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 37/40] scsi: lpfc: Fix secure firmware updates alexander.levin
2017-12-13 1:59 ` [PATCH AUTOSEL for 3.18 40/40] tcp: fix under-evaluated ssthresh in TCP Vegas alexander.levin
2017-12-21 9:54 ` Greg KH
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