• Frederic Weisbecker's avatar
    nohz: Restore NMI safe local irq work for local nohz kick · 40bea039
    Frederic Weisbecker authored
    The local nohz kick is currently used by perf which needs it to be
    NMI-safe. Recent commit though (7d1311b9
    
    )
    changed its implementation to fire the local kick using the remote kick
    API. It was convenient to make the code more generic but the remote kick
    isn't NMI-safe.
    
    As a result:
    
    	WARNING: CPU: 3 PID: 18062 at kernel/irq_work.c:72 irq_work_queue_on+0x11e/0x140()
    	CPU: 3 PID: 18062 Comm: trinity-subchil Not tainted 3.16.0+ #34
    	0000000000000009 00000000903774d1 ffff880244e06c00 ffffffff9a7f1e37
    	0000000000000000 ffff880244e06c38 ffffffff9a0791dd ffff880244fce180
    	0000000000000003 ffff880244e06d58 ffff880244e06ef8 0000000000000000
    	Call Trace:
    	<NMI>  [<ffffffff9a7f1e37>] dump_stack+0x4e/0x7a
    	[<ffffffff9a0791dd>] warn_slowpath_common+0x7d/0xa0
    	[<ffffffff9a07930a>] warn_slowpath_null+0x1a/0x20
    	[<ffffffff9a17ca1e>] irq_work_queue_on+0x11e/0x140
    	[<ffffffff9a10a2c7>] tick_nohz_full_kick_cpu+0x57/0x90
    	[<ffffffff9a186cd5>] __perf_event_overflow+0x275/0x350
    	[<ffffffff9a184f80>] ? perf_event_task_disable+0xa0/0xa0
    	[<ffffffff9a01a4cf>] ? x86_perf_event_set_period+0xbf/0x150
    	[<ffffffff9a187934>] perf_event_overflow+0x14/0x20
    	[<ffffffff9a020386>] intel_pmu_handle_irq+0x206/0x410
    	[<ffffffff9a0b54d3>] ? arch_vtime_task_switch+0x63/0x130
    	[<ffffffff9a01937b>] perf_event_nmi_handler+0x2b/0x50
    	[<ffffffff9a007b72>] nmi_handle+0xd2/0x390
    	[<ffffffff9a007aa5>] ? nmi_handle+0x5/0x390
    	[<ffffffff9a0d131b>] ? lock_release+0xab/0x330
    	[<ffffffff9a008062>] default_do_nmi+0x72/0x1c0
    	[<ffffffff9a0c925f>] ? cpuacct_account_field+0xcf/0x200
    	[<ffffffff9a008268>] do_nmi+0xb8/0x100
    
    Lets fix this by restoring the use of local irq work for the nohz local
    kick.
    Reported-by: default avatarCatalin Iacob <iacobcatalin@gmail.com>
    Reported-and-tested-by: default avatarDave Jones <davej@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    40bea039
tick-sched.c 29.9 KB