Description of problem: After booting kernel-4.3.5-301.fc23.x86_64, journald have logged the following kernel error. It occurs on a Supermicro server with mainboard X8DAH. The server seems to be usable (using ssh), but I think the kernel should not produce a backtrace. kernel: ------------[ cut here ]------------ kernel: WARNING: CPU: 6 PID: 1400 at drivers/dma/ioat/dca.c:342 ioat_dca_init+0x17c/0x1a0 [ioatdma]() kernel: ioatdma 0000:80:16.0: APICID_TAG_MAP set incorrectly by BIOS, disabling DCA kernel: Modules linked in: edac_core ioatdma(+) tpm_infineon lpc_ich shpchp snd_hwdep i2c_i801 acpi_cpufreq tpm_tis snd_pcm_oss snd_seq snd_seq_device snd_pcm snd_timer vboxnetadp(OE) nfsd vbo kernel: CPU: 6 PID: 1400 Comm: systemd-udevd Tainted: G OE 4.3.5-301.fc23.x86_64 #1 kernel: Hardware name: Supermicro X8DAH/X8DAH, BIOS 2.1 12/30/2011 kernel: 0000000000000000 00000000d0cca38e ffff8823e6067958 ffffffff813a63ef kernel: ffff8823e60679a0 ffff8823e6067990 ffffffff810a07d2 ffff8811ea296000 kernel: ffff8811ea1aac10 ffff8823e9d04d00 ffffc900197f0100 0000000000000100 kernel: Call Trace: kernel: [<ffffffff813a63ef>] dump_stack+0x44/0x55 kernel: [<ffffffff810a07d2>] warn_slowpath_common+0x82/0xc0 kernel: [<ffffffff810a08e4>] warn_slowpath_fmt_taint+0x54/0x70 kernel: [<ffffffffa0375f0c>] ioat_dca_init+0x17c/0x1a0 [ioatdma] kernel: [<ffffffffa0371e2e>] ioat_pci_probe+0x85e/0xdc0 [ioatdma] kernel: [<ffffffff8178184e>] ? _raw_spin_unlock_irqrestore+0xe/0x10 kernel: [<ffffffff813eff35>] local_pci_probe+0x45/0xa0 kernel: [<ffffffff813f131d>] pci_device_probe+0xfd/0x140 kernel: [<ffffffff814d9d12>] driver_probe_device+0x222/0x480 kernel: [<ffffffff814d9ff4>] __driver_attach+0x84/0x90 kernel: [<ffffffff814d9f70>] ? driver_probe_device+0x480/0x480 kernel: [<ffffffff814d77ec>] bus_for_each_dev+0x6c/0xc0 kernel: [<ffffffff814d94ce>] driver_attach+0x1e/0x20 kernel: [<ffffffff814d900b>] bus_add_driver+0x1eb/0x280 kernel: [<ffffffffa0361000>] ? 0xffffffffa0361000 kernel: [<ffffffff814da840>] driver_register+0x60/0xe0 kernel: [<ffffffff813ef91c>] __pci_register_driver+0x4c/0x50 kernel: [<ffffffffa036108c>] ioat_init_module+0x8c/0x1000 [ioatdma] kernel: [<ffffffff81002123>] do_one_initcall+0xb3/0x200 kernel: [<ffffffff8120435e>] ? kmem_cache_alloc_trace+0x19e/0x220 kernel: [<ffffffff811a4a27>] ? do_init_module+0x27/0x1e5 kernel: [<ffffffff811a4a5f>] do_init_module+0x5f/0x1e5 kernel: [<ffffffff8112554e>] load_module+0x201e/0x2630 kernel: [<ffffffff81121a10>] ? __symbol_put+0x60/0x60 kernel: [<ffffffff811e584c>] ? alloc_vmap_area+0x2fc/0x360 kernel: [<ffffffff81125cae>] SyS_init_module+0x14e/0x190 kernel: [<ffffffff81781dae>] entry_SYSCALL_64_fastpath+0x12/0x71 kernel: ---[ end trace 9c3a43c266863a7c ]--- Version-Release number of selected component (if applicable): kernel-4.3.5-301.fc23.x86_64 (see bug 1305181) How reproducible: Always, it occurs after each reboot.
*********** MASS BUG UPDATE ************** We apologize for the inconvenience. There is a large number of bugs to go through and several of them have gone stale. Due to this, we are doing a mass bug update across all of the Fedora 23 kernel bugs. Fedora 23 has now been rebased to 4.7.4-100.fc23. Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel. If you have moved on to Fedora 24 or 25, and are still experiencing this issue, please change the version to Fedora 24 or 25. If you experience different issues, please open a new bug report for those.
Created attachment 1206962 [details] Output of dmesg with kernel 4.7.5-200.fc24.x86_64 The problem still exists with kernel 4.7.5-200.fc24.x86_64. I have attached the output of dmesg containing the backtrace with this kernel.
This is warning about a BIOS bug and the change to a WARN_ON_ONCE was made deliberately https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f3c78f8515dd4cb9e26040ebb54cf589d21137ee . A real fix would need to come from the BIOS so there isn't much the kernel can do.