When i enable IOMMU in the bios, i start getting this in the dmesg:

[51211.395291] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x0000000000089460 flags=0x0020]
[51211.395294] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x0000000000089440 flags=0x0020]
[51211.395298] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x0000000000089470 flags=0x0020]
[51211.395302] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x0000000000089480 flags=0x0020]
[51211.395309] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x00000000000894d0 flags=0x0020]
[51211.395310] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x00000000000894c0 flags=0x0020]
[51211.395312] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x00000000000894d0 flags=0x0020]
[51211.395316] AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.4 domain=0x0012 address=0x00000000000894e0 flags=0x0020]


i run memtest86+ didn't show any problem

From searching the net, people point that adding iommu=pt fix the problem, but i'm not sure if this is not just hiding the problem. The computer is new, with IOMMU disable in bios i get no problem, so i think this is not a hardware problem.

My board is a asus A88X-PLUS with a A10-7850K

The /proc/cpuinfo (only last cpu):
processor	: 3
vendor_id	: AuthenticAMD
cpu family	: 21
model		: 48
model name	: AMD A10-7850K Radeon R7, 12 Compute Cores 4C+8G
stepping	: 1
microcode	: 0x6003106
cpu MHz		: 1700.000
cache size	: 2048 KB
physical id	: 0
siblings	: 4
core id		: 3
cpu cores	: 2
apicid		: 19
initial apicid	: 3
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid aperfmperf eagerfpu pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 popcnt aes xsave avx f16c lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm topoext perfctr_core perfctr_nb arat cpb hw_pstate npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold vmmcall fsgsbase bmi1 xsaveopt
bugs		: fxsave_leak
bogomips	: 8399.99
TLB size	: 1536 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 48 bits physical, 48 bits virtual
power management: ts ttp tm 100mhzsteps hwpstate cpb eff_freq_ro [13]


My lspci is:
00:00.0 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 1422
00:00.2 IOMMU: AMD [Advanced Micro Devices, Inc.] Device 1423
00:01.0 VGA compatible controller: AMD/ATI [Advanced Micro Devices, Inc.] Device 130f
00:01.1 Audio device: AMD/ATI [Advanced Micro Devices, Inc.] Device 1308
00:02.0 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 1424
00:03.0 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 1424
00:04.0 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 1424
00:10.0 USB controller: AMD [Advanced Micro Devices, Inc.] FCH USB XHCI Controller (rev 09)
00:10.1 USB controller: AMD [Advanced Micro Devices, Inc.] FCH USB XHCI Controller (rev 09)
00:11.0 SATA controller: AMD [Advanced Micro Devices, Inc.] FCH SATA Controller [AHCI mode] (rev 40)
00:12.0 USB controller: AMD [Advanced Micro Devices, Inc.] FCH USB OHCI Controller (rev 11)
00:12.2 USB controller: AMD [Advanced Micro Devices, Inc.] FCH USB EHCI Controller (rev 11)
00:13.0 USB controller: AMD [Advanced Micro Devices, Inc.] FCH USB OHCI Controller (rev 11)
00:13.2 USB controller: AMD [Advanced Micro Devices, Inc.] FCH USB EHCI Controller (rev 11)
00:14.0 SMBus: AMD [Advanced Micro Devices, Inc.] FCH SMBus Controller (rev 16)
00:14.2 Audio device: AMD [Advanced Micro Devices, Inc.] FCH Azalia Controller (rev 01)
00:14.3 ISA bridge: AMD [Advanced Micro Devices, Inc.] FCH LPC Bridge (rev 11)
00:14.4 PCI bridge: AMD [Advanced Micro Devices, Inc.] FCH PCI Bridge (rev 40)
00:15.0 PCI bridge: AMD [Advanced Micro Devices, Inc.] Hudson PCI to PCI bridge (PCIE port 0)
00:15.2 PCI bridge: AMD [Advanced Micro Devices, Inc.] Hudson PCI to PCI bridge (PCIE port 2)
00:18.0 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 141a
00:18.1 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 141b
00:18.2 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 141c
00:18.3 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 141d
00:18.4 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 141e
00:18.5 Host bridge: AMD [Advanced Micro Devices, Inc.] Device 141f
01:06.0 Multimedia video controller: Brooktree Corporation Bt878 Video Capture (rev 11)
01:06.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture (rev 11)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168 PCI Express Gigabit Ethernet controller (rev 0c)

Thanks