Re: [PATCH] [RFC] Potential fix for leapsecond caused futex relatedload spikes

[Prarit Bhargava]

John,

I was hit by the futex issue as well.  I saw your patch and quickly did a test
with top-of-tree + your patch using your reproducer.  I end up with warnings
from the smp_call_function code followed by all sorts of deadlocks, etc.

I haven't had a chance to debug and will start doing so shortly ...

intel-canoepass-02 login: [  108.479555] Clock: inserting leap second 23:59:60 UTC
[  108.485199] ------------[ cut here ]------------
[  108.490368] WARNING: at kernel/smp.c:461 smp_call_function_many+0xbd/0x260()
[  108.498236] Hardware name: S2600CP
[  108.502060] Modules linked in: nfs nfs_acl auth_rpcgss fscache lockd sunrpc
kvm_intel igb coretemp kvm ixgbe ptp pps_core ioatdma mdio tpm_tis crc32c_intel
wmi joydev dca tpm lpc_ich ghash_clmulni_intel sb_edac mfd_core edac_core
i2c_i801 microcode pcspkr tpm_bios hid_generic isci libsas scsi_transport_sas
mgag200 i2c_algo_bit drm_kms_helper ttm drm i2c_core [last unloaded: scsi_wait_scan]
[  108.540561] Pid: 1328, comm: leaptest Not tainted 3.5.0-rc4+ #4
[  108.547169] Hypervisor: no hypervisor
[  108.551273] Call Trace:
[  108.554019]  <IRQ>  [<ffffffff8105814f>] warn_slowpath_common+0x7f/0xc0
[  108.561398]  [<ffffffff810581aa>] warn_slowpath_null+0x1a/0x20
[  108.567911]  [<ffffffff810b39bd>] smp_call_function_many+0xbd/0x260
[  108.574931]  [<ffffffff8107e960>] ? hrtimer_wakeup+0x30/0x30
[  108.581242]  [<ffffffff8107e960>] ? hrtimer_wakeup+0x30/0x30
[  108.587560]  [<ffffffff810b3cb2>] smp_call_function+0x22/0x30
[  108.593982]  [<ffffffff810b3d18>] on_each_cpu+0x28/0x70
[  108.599825]  [<ffffffff8107ef7c>] clock_was_set+0x1c/0x30
[  108.605847]  [<ffffffff810a71d5>] do_timer+0x315/0x570
[  108.611592]  [<ffffffff810adb18>] tick_do_update_jiffies64+0x78/0xc0
[  108.618680]  [<ffffffff810add28>] tick_sched_timer+0xb8/0xc0
[  108.624991]  [<ffffffff8107ed03>] __run_hrtimer+0x73/0x1d0
[  108.631111]  [<ffffffff810adc70>] ? tick_nohz_handler+0x110/0x110
[  108.637908]  [<ffffffff8107f5d7>] hrtimer_interrupt+0xd7/0x1f0
[  108.644447]  [<ffffffff81610c19>] smp_apic_timer_interrupt+0x69/0x99
[  108.651550]  [<ffffffff8160f98a>] apic_timer_interrupt+0x6a/0x70
[  108.658255]  <EOI>
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