FYI, we noticed below warning log on https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/core commit 5f7e03e6dc37a3cc74b52d42f324a065dcc08b09 ("perf: Verify we have a single perf_hw_context PMU") [ 9.417003] PCI-DMA: using GART IOMMU. [ 9.420991] PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture [ 9.434451] ------------[ cut here ]------------ [ 9.439342] WARNING: CPU: 8 PID: 1 at kernel/events/core.c:7689 perf_pmu_register+0x37a/0x3a0 [ 9.450128] Modules linked in: [ 9.453494] CPU: 8 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc1-00030-g5f7e03e #1 [ 9.461370] Hardware name: Supermicro H8DGU/H8DGU, BIOS 2.0 09/08/11 [ 9.468737] 0000000000000000 ffff88040dd7fd78 ffffffff8142e49a 0000000000000000 [ 9.476857] 0000000000000000 ffff88040dd7fdb8 ffffffff8107b9f1 00001e0900000000 [ 9.484952] ffffffff81e12480 0000000000000006 ffffffff81c84df9 ffffffff81fdc877 [ 9.493039] Call Trace: [ 9.495723] [<ffffffff8142e49a>] dump_stack+0x63/0x89 [ 9.501095] [<ffffffff8107b9f1>] __warn+0xd1/0xf0 [ 9.506118] [<ffffffff81fdc877>] ? init_cpu_already_online+0x1d/0x1d [ 9.512793] [<ffffffff8107badd>] warn_slowpath_null+0x1d/0x20 [ 9.518858] [<ffffffff8116315a>] perf_pmu_register+0x37a/0x3a0 [ 9.525012] [<ffffffff81fdc8ee>] amd_uncore_init+0x77/0x23c [ 9.530906] [<ffffffff81fdc877>] ? init_cpu_already_online+0x1d/0x1d [ 9.537580] [<ffffffff81002123>] do_one_initcall+0xb3/0x1d0 [ 9.543475] [<ffffffff81fda11b>] kernel_init_freeable+0x192/0x21f [ 9.549890] [<ffffffff818e94ce>] kernel_init+0xe/0x110 [ 9.555346] [<ffffffff818f6782>] ret_from_fork+0x22/0x40 [ 9.560981] [<ffffffff818e94c0>] ? rest_init+0x90/0x90 [ 9.566467] ---[ end trace 7cdf19bd2ee3fae3 ]--- [ 9.571331] perf: AMD NB counters detected To reproduce: git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git cd lkp-tests bin/lkp install job.yaml # job file is attached in this email bin/lkp run job.yaml Thanks, Xiaolong Ye