Kernel with DMA_API_DEBUG=y print warning when wifi connection started. [ 17.242065] NET: Registered protocol family 10 [ 831.321753] brcmsmac bcma0:0: brcms_ops_bss_info_changed: qos enabled: false (implement) [ 831.321773] brcmsmac bcma0:0: brcms_ops_config: change power-save mode: false (implement) [ 831.322638] IPv6: ADDRCONF(NETDEV_UP): wifi: link is not ready [ 831.449539] ------------[ cut here ]------------ [ 831.449560] WARNING: at /usr/src/linux-3.9.8-gentoo/lib/dma-debug.c:937 check_unmap+0x5a9/0x73a() [ 831.449565] Hardware name: 1215B [ 831.449572] bcma-pci-bridge 0000:01:00.0: DMA-API: device driver failed to check map error[device address=0x00000000a3c76000] [size=1876 bytes] [mapped as single] [ 831.449577] Modules linked in: [ 831.449582] ipv6 bnep usb_storage uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core radeon dm_mod acpi_cpufreq brcmsmac mperf snd_hda_codec_realtek cordic brcmutil fbcon bitblit softcursor snd_hda_codec_hdmi font tileblit cfbfillrect cfbimgblt cfbcopyarea i2c_algo_bit drm_kms_helper ttm snd_hda_intel microcode snd_hda_codec drm pcspkr xhci_hcd snd_hwdep snd_pcm snd_page_alloc ohci_hcd ehci_pci snd_timer ehci_hcd snd atl1c bcma soundcore [ 831.449661] Pid: 1827, comm: kded4 Not tainted 3.9.8-gentoodeb #1 [ 831.449665] Call Trace: [ 831.449669] <IRQ> [<ffffffff81036901>] warn_slowpath_common+0x7e/0x99 [ 831.449686] [<ffffffff810369b0>] warn_slowpath_fmt+0x41/0x43 [ 831.449696] [<ffffffff811fbb7c>] check_unmap+0x5a9/0x73a [ 831.449705] [<ffffffff811f8e49>] ? swiotlb_tbl_unmap_single+0xd8/0xe0 [ 831.449713] [<ffffffff811fbec7>] debug_dma_unmap_page+0x5b/0x65 [ 831.449745] [<ffffffffa027844a>] dma_unmap_single_attrs.constprop.24+0x55/0x5e [brcmsmac] [ 831.449766] [<ffffffffa02784f2>] dma64_getnextrxp+0x9f/0xde [brcmsmac] [ 831.449788] [<ffffffffa0279324>] dma_rx+0x7b/0x302 [brcmsmac] [ 831.449799] [<ffffffff8143fae6>] ? _raw_spin_unlock_irqrestore+0x48/0x56 [ 831.449806] [<ffffffff810afe57>] ? cpumask_next+0x19/0x1b [ 831.449827] [<ffffffffa02518a9>] brcms_c_dpc+0x632/0x88a [brcmsmac] [ 831.449836] [<ffffffff8107164b>] ? __lock_acquire.isra.31+0x1c3/0x522 [ 831.449844] [<ffffffff810081b7>] ? native_sched_clock+0x39/0x3b [ 831.449851] [<ffffffff8106ff98>] ? get_lock_stats+0x19/0x4f [ 831.449866] [<ffffffffa0247017>] ? spin_lock_bh+0x9/0xb [brcmsmac] [ 831.449881] [<ffffffffa02485d5>] brcms_dpc+0x5d/0xb4 [brcmsmac] [ 831.449889] [<ffffffff8103c471>] tasklet_action+0x79/0xc2 [ 831.449896] [<ffffffff8103c6dd>] __do_softirq+0xb8/0x176 [ 831.449904] [<ffffffff8103c87e>] irq_exit+0x4c/0x8f [ 831.449912] [<ffffffff810033f0>] do_IRQ+0x88/0x9f [ 831.449919] [<ffffffff814400ea>] common_interrupt+0x6a/0x6a [ 831.449923] <EOI> [<ffffffff81071d80>] ? lock_acquire+0x82/0x8b [ 831.449937] [<ffffffff810e38c3>] ? spin_lock+0x9/0xb [ 831.449945] [<ffffffff8143f4d4>] _raw_spin_lock+0x3c/0x71 [ 831.449952] [<ffffffff810e38c3>] ? spin_lock+0x9/0xb [ 831.449959] [<ffffffff810e38c3>] spin_lock+0x9/0xb [ 831.449966] [<ffffffff810e4ed5>] dput+0x23/0xf9 [ 831.449973] [<ffffffff810dbd2f>] path_to_nameidata+0x1c/0x3f [ 831.449980] [<ffffffff810dcffc>] walk_component+0x160/0x1a0 [ 831.449987] [<ffffffff810dd06a>] lookup_last+0x2e/0x30 [ 831.449994] [<ffffffff810ddc4f>] path_lookupat+0x8b/0x287 [ 831.450002] [<ffffffff810cc9d3>] ? kmem_cache_alloc+0x22/0x98 [ 831.450009] [<ffffffff810dde6c>] filename_lookup.isra.52+0x21/0x57 [ 831.450016] [<ffffffff810dfcae>] user_path_at_empty+0x52/0x90 [ 831.450025] [<ffffffff8105b0b4>] ? sched_clock_cpu+0x43/0xcf [ 831.450032] [<ffffffff810703d3>] ? lock_release_holdtime.part.23+0x4e/0x55 [ 831.450041] [<ffffffff810eb695>] ? mntput_no_expire+0x1d/0x143 [ 831.450048] [<ffffffff810dfcf8>] user_path_at+0xc/0xe [ 831.450056] [<ffffffff810d808e>] vfs_fstatat+0x44/0x91 [ 831.450063] [<ffffffff810eb6b7>] ? mntput_no_expire+0x3f/0x143 [ 831.450070] [<ffffffff810d810c>] vfs_stat+0x16/0x18 [ 831.450077] [<ffffffff810d8381>] sys_newstat+0x15/0x30 [ 831.450084] [<ffffffff810d84b9>] ? sys_readlinkat+0x8f/0xc7 [ 831.450092] [<ffffffff811ed6b9>] ? lockdep_sys_exit_thunk+0x35/0x67 [ 831.450099] [<ffffffff814408d2>] system_call_fastpath+0x16/0x1b [ 831.450105] ---[ end trace 9aa21105984d63fa ]--- [ 831.450108] Mapped at: [ 831.450112] [<ffffffff811fbf1e>] debug_dma_map_page+0x4d/0x10b [ 831.450118] [<ffffffffa02786b9>] dma_map_single_attrs.constprop.25+0xc5/0xd8 [brcmsmac] [ 831.450139] [<ffffffffa027976a>] dma_rxfill+0x1bf/0x266 [brcmsmac] [ 831.450158] [<ffffffffa02523d0>] brcms_c_init+0x8cf/0xda7 [brcmsmac] [ 831.450176] [<ffffffffa02484f6>] brcms_init+0x53/0x57 [brcmsmac] [ 833.715356] wifi: authenticate with 14:a9:e3:01:f2:a8 #lspci -v 01:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01) Subsystem: AzureWave Device 2047 Flags: bus master, fast devsel, latency 0, IRQ 16 Memory at fea00000 (64-bit, non-prefetchable) [size=16K] May be this is the source of problem in https://bugzilla.kernel.org/show_bug.cgi?id=54021