Messages in this thread | | | Date | Wed, 15 Oct 2014 12:03:26 -0400 | From | Prarit Bhargava <> | Subject | Re: Lockdep warning with init_espfix_ap() |
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On 10/15/2014 11:57 AM, H. Peter Anvin wrote: > On 10/09/2014 08:35 AM, Prarit Bhargava wrote: >> >> Non-fatal warning seen with latest kernel tree during kernel boot. >> >> WARNING: CPU: 64 PID: 0 at kernel/locking/lockdep.c:2744 >> lockdep_trace_alloc+0xdd/0xe0() >> DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) >> Modules linked in: >> >> CPU: 64 PID: 0 Comm: swapper/64 Not tainted 3.17.0+ #10 >> Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS >> BIVTSDP1.86B.0049.R00.1403081207 03/08/2014 >> 0000000000000000 d27b9ea0e3821f35 ffff88084edc3ce0 ffffffff8171cbd8 >> ffff88084edc3d28 ffff88084edc3d18 ffffffff8108424d 0000000000000046 >> 0000000000000000 00000000000000d0 0000000000000002 0000000000000000 >> Call Trace: >> [<ffffffff8171cbd8>] dump_stack+0x4d/0x66 >> [<ffffffff8108424d>] warn_slowpath_common+0x7d/0xa0 >> [<ffffffff810842cc>] warn_slowpath_fmt+0x5c/0x80 >> [<ffffffff810e3e2d>] lockdep_trace_alloc+0xdd/0xe0 >> [<ffffffff811c0aaf>] __alloc_pages_nodemask+0x9f/0x4b0 >> [<ffffffff81025365>] ? native_sched_clock+0x35/0xa0 >> [<ffffffff810253d9>] ? sched_clock+0x9/0x10 >> [<ffffffff8120981a>] alloc_page_interleave+0x3a/0x90 >> [<ffffffff8120ae8d>] alloc_pages_current+0x17d/0x1f0 >> [<ffffffff811bab24>] ? __get_free_pages+0x14/0x50 >> [<ffffffff811bab24>] __get_free_pages+0x14/0x50 >> [<ffffffff8102225d>] init_espfix_ap+0x17d/0x320 >> [<ffffffff8105254e>] start_secondary+0x19e/0x350 >> ---[ end trace 2b62d796aa7ae001 ]--- >> >> Debugging ... but sorta hoping someone else may have already seen it ;) >> > > It is kind of a messy situation, because this code needs to allocate > memory but is run before the secondary CPU is fully up. As such, it is > a false positive, at least in some ways.
Interesting -- FWIW, I can reproduce this 100% of the time on _one_ system. It isn't a big deal and likely just worth noting at this point. I *always* see it when bringing up CPU 64 (of 128).
P.
> > -hpa > >
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