Created attachment 294631 [details]
dmesg output

Hello,

I use archlinux 64 bits, kernel linux 5.10.7,

since a recent update of kernel linux I notice that my webcam "Creative Labs Webcam 5 (usb-0000:00:1d.0-2)" doesn't work, this webcam uses pcw driver,

the error message in dmesg :

pwc: Failed to allocate urb buffer 0


full error in dmesg :

[  150.849789] WARNING: CPU: 2 PID: 928 at kernel/dma/mapping.c:149 dma_map_page_attrs+0x153/0x220
[  150.849790] Modules linked in: pwc ipt_REJECT nf_reject_ipv4 xt_state xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c iptable_filter it87 hwmon_vid mousedev gpio_ich snd_hda_codec_realtek snd_hda_codec_generic iTCO_wdt dvb_pll intel_pmc_bxt ledtrig_audio cx22702 iTCO_vendor_support ppdev snd_hda_codec_hdmi coretemp snd_hda_intel cx88_dvb kvm_intel cx88_vp3054_i2c snd_intel_dspcfg videobuf2_dvb dvb_core soundwire_intel kvm soundwire_generic_allocation videobuf2_vmalloc soundwire_cadence snd_hda_codec snd_ymfpci rc_winfast snd_ac97_codec snd_hda_core irqbypass soundwire_bus snd_mpu401_uart snd_opl3_lib snd_hwdep cx8800 snd_soc_core videobuf2_dma_sg videobuf2_memops snd_compress cx8802 snd_rawmidi cx88xx videobuf2_v4l2 snd_seq_device gameport snd_pcm_dmaengine ac97_bus tveeprom videobuf2_common pcspkr videodev i2c_i801 lpc_ich snd_pcm mc i2c_smbus snd_timer snd soundcore r8169 intel_agp realtek intel_gtt mac_hid mdio_devres libphy parport_pc parport acpi_cpufreq sg
[  150.849872]  crypto_user fuse bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 ata_generic pata_acpi serio_raw sr_mod cdrom pata_jmicron usbhid radeon i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec ttm drm agpgart
[  150.849903] CPU: 2 PID: 928 Comm: ffmpeg Not tainted 5.10.7-arch1-1 #1
[  150.849905] Hardware name: Gigabyte Technology Co., Ltd. P35-DS3L/P35-DS3L, BIOS F9 06/19/2009
[  150.849908] RIP: 0010:dma_map_page_attrs+0x153/0x220
[  150.849911] Code: 74 72 4d 89 c8 4c 89 df e8 0a 2b 00 00 eb 8f 48 85 ff 74 0c 48 39 df 48 0f 47 fb e9 79 ff ff ff 48 89 df e9 71 ff ff ff 0f 0b <0f> 0b 48 c7 c0 ff ff ff ff e9 66 ff ff ff 48 89 f7 48 2b 78 18 e9
[  150.849913] RSP: 0018:ffffb44941dfbcb0 EFLAGS: 00010246
[  150.849915] RAX: 0000000000000000 RBX: ffffa000fae41000 RCX: 0000000000000002
[  150.849917] RDX: 0000000000002580 RSI: ffffe19d85031d00 RDI: ffffa000ee66c0a0
[  150.849918] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[  150.849920] R10: 0000000000000000 R11: ffffa000ee66c0a0 R12: ffffa000ee66c000
[  150.849921] R13: ffffa00100c74000 R14: ffffa000fd470000 R15: 0000000000000000
[  150.849924] FS:  00007f26bd268bc0(0000) GS:ffffa001e7d00000(0000) knlGS:0000000000000000
[  150.849926] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  150.849928] CR2: 00007f26c5d50448 CR3: 000000013e368000 CR4: 00000000000406e0
[  150.849929] Call Trace:
[  150.849942]  start_streaming+0x292/0x4a0 [pwc]
[  150.849953]  vb2_start_streaming+0x63/0x100 [videobuf2_common]
[  150.849957]  vb2_core_streamon+0x54/0xb0 [videobuf2_common]
[  150.849984]  __video_do_ioctl+0x3ba/0x3f0 [videodev]
[  150.849995]  video_usercopy+0x175/0x5a0 [videodev]
[  150.850005]  ? v4l_print_control+0x20/0x20 [videodev]
[  150.850015]  v4l2_ioctl+0x48/0x50 [videodev]
[  150.850024]  __x64_sys_ioctl+0x83/0xb0
[  150.850029]  do_syscall_64+0x33/0x40
[  150.850032]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  150.850035] RIP: 0033:0x7f26c3b0af6b
[  150.850037] Code: 89 d8 49 8d 3c 1c 48 f7 d8 49 39 c4 72 b5 e8 1c ff ff ff 85 c0 78 ba 4c 89 e0 5b 5d 41 5c c3 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d d5 a0c 00 f7 d8 64 89 01 48
[  150.850039] RSP: 002b:00007ffd06dad758 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  150.850042] RAX: ffffffffffffffda RBX: 000055efde7a42c0 RCX: 00007f26c3b0af6b
[  150.850044] RDX: 00007ffd06dad798 RSI: 0000000040045612 RDI: 0000000000000003
[  150.850045] RBP: 000055efde7a39c0 R08: 0000000000000003 R09: 000000000069f000
[  150.850047] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000032315559
[  150.850048] R13: 000055efde7a42c0 R14: 000000000000000d R15: 00007ffd06dad798
[  150.850052] ---[ end trace 13224487c0278722 ]---
[  150.850055] pwc: Failed to allocate urb buffer 0

With a previous kernel linux (end of november 2020) the webcam works without problems, no error about memory allocation,
so it's likely a recent commit in kernel linux about pcw driver, or V4L2 which triggers this bug.