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Date: Thu, 11 Feb 2016 20:27:41 +0100
From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: x86-ml <x86@kernel.org>, lkml <linux-kernel@vger.kernel.org>
Subject: WARNING: CPU: 0 PID: 3031 at
 ./arch/x86/include/asm/fpu/internal.h:530 fpu__restore+0x90/0x130()
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Hey Andy,

can you make any sense of this:

[   90.573923] ------------[ cut here ]------------
[   90.574977] WARNING: CPU: 0 PID: 3031 at ./arch/x86/include/asm/fpu/internal.h:530 fpu__restore+0x90/0x130()
[   90.576108] Modules linked in: hid_generic usbhid hid snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic iTCO_wdt iTCO_vendor_support arc4 x86_pkg_temp_thermal coretemp kvm_intel kvm irqbypass crc32_pclmul crc32c_intel iwldvm mac80211 aesni_intel xts snd_hda_intel input_leds aes_i586 snd_hda_codec sdhci_pci lrw iwlwifi snd_hwdep gf128mul snd_hda_core ablk_helper cryptd ehci_pci pcspkr serio_raw xhci_pci sdhci snd_pcm sg mmc_core i2c_i801 cfg80211 lpc_ich mfd_core e1000e snd_timer ehci_hcd xhci_hcd thinkpad_acpi nvram wmi snd battery soundcore led_class ac thermal
[   90.580570] CPU: 0 PID: 3031 Comm: bash Not tainted 4.5.0-rc3+ #1
[   90.581380] Hardware name: LENOVO 2320CTO/2320CTO, BIOS G2ET86WW (2.06 ) 11/13/2012
[   90.582325]  00000000 00000286 f158be4c c12cce56 00000000 00000000 f158be80 c10567fb
[   90.583179]  c1866c2c 00000000 00000bd7 c1859e8c 00000212 c1025ab0 00000212 c1025ab0
[   90.584142]  f2012b00 f2011f00 f2012d80 f158be90 c10568d2 00000009 00000000 f158bea4
[   90.585002] Call Trace:
[   90.585854]  [<c12cce56>] dump_stack+0x5f/0x89
[   90.586703]  [<c10567fb>] warn_slowpath_common+0x8b/0xc0
[   90.587559]  [<c1025ab0>] ? fpu__restore+0x90/0x130
[   90.588520]  [<c1025ab0>] ? fpu__restore+0x90/0x130
[   90.589353]  [<c10568d2>] warn_slowpath_null+0x22/0x30
[   90.590175]  [<c1025ab0>] fpu__restore+0x90/0x130
[   90.590993]  [<c1027098>] __fpu__restore_sig+0x268/0x4c0
[   90.591816]  [<c102751f>] fpu__restore_sig+0x2f/0x50
[   90.592636]  [<c101a6c9>] restore_sigcontext+0xe9/0x110
[   90.593449]  [<c101af3c>] sys_sigreturn+0x9c/0xb0
[   90.594263]  [<c1001bd9>] do_syscall_32_irqs_on+0x59/0x340
[   90.595079]  [<c169979d>] entry_INT80_32+0x31/0x31
[   90.595922] ---[ end trace be617bef2982f473 ]---

This is rc3 + latest tip/master and it happened when I did "make
mrproper" in the kernel repo.

>>From a quick stare, it looks to me we're running do_syscall_32_irqs_on()
with IRQs on, sys_sigreturn() does current_pt_regs() but
__fpu__restore_sig() derefs current again and could be that that second
"current" is another current which already has ->fpregs_active set ?

FPU + signal handling code in a single backtrace. My favourite!

:-\

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.