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[209.132.180.67]) by mx.google.com with ESMTP id c6si2708523pgn.681.2018.02.10.04.50.03; Sat, 10 Feb 2018 04:50:17 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@gmail.com header.s=20161025 header.b=nz+Pcm1o; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751145AbeBJMtU (ORCPT + 99 others); Sat, 10 Feb 2018 07:49:20 -0500 Received: from mail-ua0-f193.google.com ([209.85.217.193]:39699 "EHLO mail-ua0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750832AbeBJMtR (ORCPT ); Sat, 10 Feb 2018 07:49:17 -0500 Received: by mail-ua0-f193.google.com with SMTP id r4so6858153uak.6; Sat, 10 Feb 2018 04:49:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=kCR6NyhTmpN8AIB5LDNX9OuhyEWrGGAzHQCdvjLVBws=; b=nz+Pcm1osJrJ46t3t7tAyAkvp/nwZv4wQiJLlUrPO7cS2i8jWopy0m3lnEYAOdo1ag SAtngtXkRY3zRLY651R/yqyXIN2iL8Yrj2/MjAoBjjdYAT+qQsp8Xtrtfbs7p+njt3en zu2DZlB6tSjzv8mb8PL9gjPfXBVunUfRAx1so/JbkJzTaaxVq+uwfIpZJYuHBmIYgq8q KCnd/WB0Uo5OC0bbQdQUt2yvVyIc2QJ0GxC2dbmCICXxHPzxsBioQainbw/8qWnwO7Gi WVs0eLvwOaMRzZs1jXFzO8QbwNBBhXAwL0/aMYmzUVowF6VflkQ1HfFOLMaiT4KZ7qHG BVdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=kCR6NyhTmpN8AIB5LDNX9OuhyEWrGGAzHQCdvjLVBws=; b=uWPUzz9INC87asBeQTpZxHq01kkeIH2uKMwZGxiQJAWWukWVnguT0fpwARsdMqjXgT RMOCi1wHv2QKy9/dSq2v1NjeiQMMSrue5AJehdkDJwbj0nOL1BZHjosXj5Pgjlzo1edF orMrH5Jc1pLMG2156Ag54LucJXMreQ1LnCRlDzr+VPFZPZlYABSpDgE82tuO/5wc97zp B5oFA3BZgD7ojRV5n6qMJa7MembrlztdRQmr0dSDbXaq+uXVh/t3wkjD2XlDASScvtqx lRomotuf1bJXIrZc8r+J8SdPsrrZYrsYOvLzZw33hu/nB88FpUGd3b+k3FJYydxrdRTj fgBQ== X-Gm-Message-State: APf1xPAglR6gmfXdhkHAsY/TGR4zXjPRGf+fmFMWIaAH/W6STqURYhti ESivcbTj3QdY89W/1eHP2M2Ps86bjc4ArxZdxom9PGQv X-Received: by 10.176.97.207 with SMTP id m15mr4765432uan.136.1518266955786; Sat, 10 Feb 2018 04:49:15 -0800 (PST) MIME-Version: 1.0 Received: by 10.176.78.22 with HTTP; Sat, 10 Feb 2018 04:48:55 -0800 (PST) In-Reply-To: <22661745.JSDcq4C6er@amdc3058> References: <1479153557-20849-1-git-send-email-malat@debian.org> <2327325.HZp8yQY9TN@amdc3058> <22661745.JSDcq4C6er@amdc3058> From: Mathieu Malaterre Date: Sat, 10 Feb 2018 13:48:55 +0100 X-Google-Sender-Auth: aWdav0IuOAHPlzz1czvaJ170-_0 Message-ID: Subject: Re: [PATCH v3] Fix loading of module radeonfb on PowerMac To: Bartlomiej Zolnierkiewicz Cc: Tomi Valkeinen , Lennart Sorensen , Benjamin Herrenschmidt , Linux Fbdev development list , dri-devel , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Feb 8, 2018 at 2:28 PM, Bartlomiej Zolnierkiewicz wrote: > On Wednesday, January 31, 2018 08:51:23 PM Mathieu Malaterre wrote: >> Bartlomiej, >> >> On Wed, Jan 31, 2018 at 12:57 PM, Bartlomiej Zolnierkiewicz >> wrote: >> > On Tuesday, January 30, 2018 02:14:10 PM Mathieu Malaterre wrote: >> >> Bartlomiej, >> >> >> >> On Wed, Jan 3, 2018 at 3:47 PM, Bartlomiej Zolnierkiewicz >> >> wrote: >> >> > >> >> > On Thursday, December 21, 2017 11:07:56 PM Mathieu Malaterre wrote: >> >> >> When the linux kernel is build with (typical kernel ship with Debian >> >> >> installer): >> >> >> >> >> >> CONFIG_FB_OF=y >> >> >> CONFIG_VT_HW_CONSOLE_BINDING=y >> >> >> CONFIG_FB_RADEON=m >> >> >> >> >> >> The offb driver takes precedence over module radeonfb. It is then >> >> >> impossible to load the module, error reported is: >> >> >> >> >> >> [ 96.551486] radeonfb 0000:00:10.0: enabling device (0006 -> 0007) >> >> >> [ 96.551526] radeonfb 0000:00:10.0: BAR 0: can't reserve [mem 0x98000000-0x9fffffff pref] >> >> >> [ 96.551531] radeonfb (0000:00:10.0): cannot request region 0. >> >> >> [ 96.551545] radeonfb: probe of 0000:00:10.0 failed with error -16 >> >> >> >> >> >> This patch reproduce the behavior of the module radeon, so as to make it >> >> >> possible to load radeonfb when offb is first loaded. >> >> >> >> >> >> It should be noticed that `offb_destroy` is never called which explain the >> >> >> need to skip error detection on the radeon side. >> >> > >> >> > This still needs to be explained more, from my last mail: >> >> > >> >> > "The last put_fb_info() on fb_info should call ->fb_destroy >> >> > (offb_destroy in our case) and remove_conflicting_framebuffers() >> >> > is calling put_fb_info() so there is some extra reference on >> >> > fb_info somewhere preventing it from going away. >> >> > >> >> > Please look into fixing this." >> >> >> >> I am not familiar with the fb stuff internals but here is what I see: >> >> >> >> # modprobe radeonfb >> >> >> >> leads to: >> >> >> >> [ 52.058546] bus: 'pci': add driver radeonfb >> >> [ 52.058588] bus: 'pci': driver_probe_device: matched device >> >> 0000:00:10.0 with driver radeonfb >> >> [ 52.058595] bus: 'pci': really_probe: probing driver radeonfb with >> >> device 0000:00:10.0 >> >> [ 52.058608] devices_kset: Moving 0000:00:10.0 to end of list >> >> [ 52.058613] radeonfb_pci_register BEGIN >> >> [ 52.058634] radeonfb 0000:00:10.0: enabling device (0006 -> 0007) >> >> >> >> [ 52.058666] checking generic (9c008000 96000) vs hw (98000000 8000000) >> >> [ 52.058667] fb: switching to radeonfb from OFfb ATY,RockHo >> >> [ 52.058844] Console: switching to colour dummy device 80x25 >> >> [ 52.058860] device: 'fb0': device_unregister >> >> [ 52.058956] PM: Removing info for No Bus:fb0 >> >> [ 52.059014] device: 'fb0': device_create_release >> >> >> >> >> >> [ 52.059048] device: 'vtcon1': device_unregister >> >> [ 52.059076] PM: Removing info for No Bus:vtcon1 >> >> [ 52.059091] device: 'vtcon1': device_create_release >> >> [ 52.059107] radeonfb 0000:00:10.0: BAR 0: can't reserve [mem >> >> 0x98000000-0x9fffffff pref] >> >> [ 52.256151] aper_base: 98000000 MC_FB_LOC to: 9bff9800, MC_AGP_LOC >> >> to: ffffa000 >> >> [ 52.256157] radeonfb (0000:00:10.0): Found 32768k of DDR 64 bits >> >> wide videoram >> >> >> >> I can confirm that offb_destroy is never called (not sure exactly >> >> why), but in any case the call to radeon_kick_out_firmware_fb happen >> >> much earlier, at least before the put_fb_info. >> > >> > It is okay, put_fb_info() is called indirectly by radeon_kick_out_firmware_fb() >> > >> > radeon_kick_out_firmware_fb() >> > remove_conflicting_framebuffers() >> > do_remove_conflicting_framebuffers() >> > do_unregister_framebuffer() >> > put_fb_info() >> > >> > offb_destroy() is not called because there is an extra reference on old >> > fb_info (->count == 2): >> > >> > static void put_fb_info(struct fb_info *fb_info) >> > { >> > if (!atomic_dec_and_test(&fb_info->count)) >> > return; >> > if (fb_info->fbops->fb_destroy) >> > fb_info->fbops->fb_destroy(fb_info); >> > } >> > >> > The question is why there is an extra reference, probably user-space >> > is still holding the fb_info reference obtained in fb_open() call and >> > fb_release() is never called. Besides not calling fbops->fb_destroy() >> > this also causes missing call of fbops->fb_release() (in fb_release()) >> > which some fb drivers are implementing (but not offb.c). >> > >> >> Could you describe a bit more the chain of calls you were thinking of ? >> > >> > Please add WARN_ON(1) to get_fb_info() and put_fb_info() so we can check >> > from the stacktrace if it is actually fb_open() that holds the extra >> > old fb_info reference. >> > >> > drivers/video/fbdev/core/fbmem.c: >> > >> > static struct fb_info *get_fb_info(unsigned int idx) >> > { >> > struct fb_info *fb_info; >> > >> > if (idx >= FB_MAX) >> > return ERR_PTR(-ENODEV); >> > >> > mutex_lock(®istration_lock); >> > fb_info = registered_fb[idx]; >> > if (fb_info) >> > atomic_inc(&fb_info->count); >> > >> > if (fb_info) >> > WARN_ON(1); >> > >> > mutex_unlock(®istration_lock); >> > >> > return fb_info; >> > } >> > >> > static void put_fb_info(struct fb_info *fb_info) >> > { >> > WARN_ON(1); >> > >> > if (!atomic_dec_and_test(&fb_info->count)) >> > return; >> > if (fb_info->fbops->fb_destroy) >> > fb_info->fbops->fb_destroy(fb_info); >> > } >> >> >> Alright, here is what I see: >> >> [ 18.961639] PM: Adding info for No Bus:vcs7 >> [ 18.966448] device: 'vcsa7': device_add >> [ 18.966496] PM: Adding info for No Bus:vcsa7 >> [ 19.001701] WARNING: CPU: 0 PID: 405 at >> drivers/video/fbdev/core/fbmem.c:68 get_fb_info.part.3+0x58/0x7c >> [ 19.001715] Modules linked in: uinput snd_aoa_codec_toonie >> snd_aoa_fabric_layout snd_aoa snd_aoa_i2sbus snd_aoa_soundbus snd_pcm >> snd_timer snd soundcore rack_meter evdev i2c_dev sg usb_storage >> ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 fscrypto >> hid_generic usbhid hid ohci_pci ehci_pci ohci_hcd ehci_hcd sungem >> firewire_ohci sungem_phy sr_mod firewire_core crc_itu_t cdrom sd_mod >> usbcore >> [ 19.001773] CPU: 0 PID: 405 Comm: Xorg Not tainted 4.15.0+ #321 >> [ 19.001778] NIP: c039ef20 LR: c039eefc CTR: c039ef44 >> [ 19.001781] REGS: decc7c80 TRAP: 0700 Not tainted (4.15.0+) >> [ 19.001784] MSR: 00029032 CR: 28222828 XER: 00000000 >> [ 19.001795] >> GPR00: c039eefc decc7d30 c147ab00 00000000 dc3ed8c0 >> df568a6c 00000001 c147ab00 >> GPR08: df568a6c 00000002 00000000 dc280c50 28222822 >> 006f9ff4 006fff50 80000000 >> GPR16: 88000228 00000008 bfcb5b08 00000002 decc7e60 >> 80000000 ffffffea 00000041 >> GPR24: 00000000 00000006 df568a6c dc3ed8c0 df5ef1e8 >> df568a40 c08f7c18 dc198800 >> [ 19.001835] NIP [c039ef20] get_fb_info.part.3+0x58/0x7c >> [ 19.001840] LR [c039eefc] get_fb_info.part.3+0x34/0x7c >> [ 19.001842] Call Trace: >> [ 19.001848] [decc7d30] [c039eefc] get_fb_info.part.3+0x34/0x7c (unreliable) >> [ 19.001854] [decc7d40] [c039efa0] fb_open+0x5c/0x18c >> [ 19.001866] [decc7d60] [c01e0e90] chrdev_open+0xb8/0x19c >> [ 19.001872] [decc7d90] [c01d7994] do_dentry_open+0x24c/0x398 >> [ 19.001881] [decc7dc0] [c01ec378] path_openat+0x4c4/0x11b8 >> [ 19.001888] [decc7e50] [c01ee0d8] do_filp_open+0xbc/0x10c >> [ 19.001893] [decc7f00] [c01d93b0] do_sys_open+0x158/0x228 >> [ 19.001901] [decc7f40] [c00181cc] ret_from_syscall+0x0/0x40 >> [ 19.001908] --- interrupt: c01 at 0xb751b940 >> LR = 0xb751b8dc >> [ 19.001912] Instruction dump: >> [ 19.001917] 7fc3f378 57ff103a 482cc171 3d20c093 39291a84 7fe9f82e >> 2f9f0000 419e0018 >> [ 19.001927] 7d20f828 31290001 7d20f92d 40a2fff4 <0fe00000> 7fc3f378 >> 482cca69 7fe3fb78 >> [ 19.001938] ---[ end trace e0bf4192eb1c4f60 ]--- >> [ 19.001985] WARNING: CPU: 0 PID: 405 at >> drivers/video/fbdev/core/fbmem.c:77 put_fb_info+0x18/0x68 >> [ 19.001988] Modules linked in: uinput snd_aoa_codec_toonie >> snd_aoa_fabric_layout snd_aoa snd_aoa_i2sbus snd_aoa_soundbus snd_pcm >> snd_timer snd soundcore rack_meter evdev i2c_dev sg usb_storage >> ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 fscrypto >> hid_generic usbhid hid ohci_pci ehci_pci ohci_hcd ehci_hcd sungem >> firewire_ohci sungem_phy sr_mod firewire_core crc_itu_t cdrom sd_mod >> usbcore >> [ 19.002028] CPU: 0 PID: 405 Comm: Xorg Tainted: G W >> 4.15.0+ #321 >> [ 19.002031] NIP: c039e6ec LR: c039eeb0 CTR: c039ee48 >> [ 19.002035] REGS: decc7e10 TRAP: 0700 Tainted: G W (4.15.0+) >> [ 19.002037] MSR: 00029032 CR: 28000222 XER: 20000000 >> [ 19.002047] >> GPR00: c039eeb0 decc7ec0 c147ab00 dc198800 dc3ed8c0 >> dc3ed8c8 00000001 c147ab00 >> GPR08: 00000000 c08fa6f8 00000000 dc280c50 28000228 >> 006f9ff4 006fff50 00000000 >> GPR16: 007001a8 00000008 bfcb5b08 007001a4 00000000 >> 0070d0c4 00000002 00000000 >> GPR24: b6ad8b1c dc3ed8c8 df5ef1e8 df3e4ee0 dc280c50 >> df5ef1e8 dc19880c dc198800 >> [ 19.002086] NIP [c039e6ec] put_fb_info+0x18/0x68 >> [ 19.002091] LR [c039eeb0] fb_release+0x68/0x80 >> [ 19.002093] Call Trace: >> [ 19.002096] [decc7ec0] [df5ef1e8] 0xdf5ef1e8 (unreliable) >> [ 19.002102] [decc7ed0] [c039eeb0] fb_release+0x68/0x80 >> [ 19.002108] [decc7ee0] [c01dd2e8] __fput+0xb4/0x260 >> [ 19.002118] [decc7f10] [c006e088] task_work_run+0xc0/0xe8 >> [ 19.002129] [decc7f30] [c000aa90] do_notify_resume+0xb4/0xb8 >> [ 19.002135] [decc7f40] [c0018b4c] do_user_signal+0x7c/0xcc >> [ 19.002140] --- interrupt: c00 at 0xb751a7d8 >> LR = 0xb751a7ac >> [ 19.002144] Instruction dump: >> [ 19.002147] 80010014 38210010 7c0803a6 4e800020 38600000 4e800020 >> 7c0802a6 90010004 >> [ 19.002157] 60000000 9421fff0 7c0802a6 90010014 <0fe00000> 7d401828 >> 314affff 7d40192d >> [ 19.002168] ---[ end trace e0bf4192eb1c4f61 ]--- >> [ 19.002595] WARNING: CPU: 0 PID: 405 at >> drivers/video/fbdev/core/fbmem.c:68 get_fb_info.part.3+0x58/0x7c >> [ 19.002601] Modules linked in: uinput snd_aoa_codec_toonie >> snd_aoa_fabric_layout snd_aoa snd_aoa_i2sbus snd_aoa_soundbus snd_pcm >> snd_timer snd soundcore rack_meter evdev i2c_dev sg usb_storage >> ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 fscrypto >> hid_generic usbhid hid ohci_pci ehci_pci ohci_hcd ehci_hcd sungem >> firewire_ohci sungem_phy sr_mod firewire_core crc_itu_t cdrom sd_mod >> usbcore >> [ 19.002645] CPU: 0 PID: 405 Comm: Xorg Tainted: G W >> 4.15.0+ #321 >> [ 19.002649] NIP: c039ef20 LR: c039eefc CTR: c039ef44 >> [ 19.002652] REGS: decc7c80 TRAP: 0700 Tainted: G W (4.15.0+) >> [ 19.002655] MSR: 00029032 CR: 28222248 XER: 00000000 >> [ 19.002664] >> GPR00: c039eefc decc7d30 c147ab00 00000000 deca0340 >> deca0348 00000001 00000000 >> GPR08: 00000000 00000002 00000000 dc280c50 28222842 >> 006f9ff4 006fff50 80000000 >> GPR16: 88000448 00000001 00000000 00000002 decc7e60 >> 80000000 ffffffea 00000041 >> GPR24: 00000000 00000006 c01e0dd8 deca0340 df5ef1e8 >> df568a40 c08f7c18 dc198800 >> [ 19.002704] NIP [c039ef20] get_fb_info.part.3+0x58/0x7c >> [ 19.002708] LR [c039eefc] get_fb_info.part.3+0x34/0x7c >> [ 19.002711] Call Trace: >> [ 19.002716] [decc7d30] [c039eefc] get_fb_info.part.3+0x34/0x7c (unreliable) >> [ 19.002722] [decc7d40] [c039efa0] fb_open+0x5c/0x18c >> [ 19.002730] [decc7d60] [c01e0e90] chrdev_open+0xb8/0x19c >> [ 19.002735] [decc7d90] [c01d7994] do_dentry_open+0x24c/0x398 >> [ 19.002743] [decc7dc0] [c01ec378] path_openat+0x4c4/0x11b8 >> [ 19.002748] [decc7e50] [c01ee0d8] do_filp_open+0xbc/0x10c >> [ 19.002754] [decc7f00] [c01d93b0] do_sys_open+0x158/0x228 >> [ 19.002760] [decc7f40] [c00181cc] ret_from_syscall+0x0/0x40 >> [ 19.002766] --- interrupt: c01 at 0xb751b940 >> LR = 0xb751b8dc >> [ 19.002770] Instruction dump: >> [ 19.002774] 7fc3f378 57ff103a 482cc171 3d20c093 39291a84 7fe9f82e >> 2f9f0000 419e0018 >> [ 19.002784] 7d20f828 31290001 7d20f92d 40a2fff4 <0fe00000> 7fc3f378 >> 482cca69 7fe3fb78 >> [ 19.002795] ---[ end trace e0bf4192eb1c4f62 ]--- >> [ 19.011629] gem 0002:20:0f.0 eth0: Link is up at 100 Mbps, full-duplex >> [ 19.011746] gem 0002:20:0f.0 eth0: Pause is disabled >> [ 19.011846] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready >> [ 19.018954] device: 'input3': device_add >> [ 19.019031] PM: Adding info for No Bus:input3 >> >> >> Then later on (after modprobe radeonfb): >> >> [ 657.135105] PM: Removing info for No Bus:fb0 >> [ 657.135164] device: 'fb0': device_create_release >> [ 657.135279] WARNING: CPU: 0 PID: 475 at >> drivers/video/fbdev/core/fbmem.c:77 put_fb_info+0x18/0x68 >> [ 657.135284] Modules linked in: radeonfb(+) uinput >> snd_aoa_codec_toonie snd_aoa_fabric_layout snd_aoa snd_aoa_i2sbus >> snd_aoa_soundbus snd_pcm snd_timer snd soundcore rack_meter evdev >> i2c_dev sg usb_storage ip_tables x_tables autofs4 ext4 crc16 mbcache >> jbd2 fscrypto hid_generic usbhid hid ohci_pci ehci_pci ohci_hcd >> ehci_hcd sungem firewire_ohci sungem_phy sr_mod firewire_core >> crc_itu_t cdrom sd_mod usbcore >> [ 657.135344] CPU: 0 PID: 475 Comm: modprobe Tainted: G W >> 4.15.0+ #321 >> [ 657.135348] NIP: c039e6ec LR: c039e834 CTR: 00000000 >> [ 657.135352] REGS: dec93af0 TRAP: 0700 Tainted: G W (4.15.0+) >> [ 657.135355] MSR: 00029032 CR: 24228822 XER: 20000000 >> [ 657.135365] >> GPR00: c039e834 dec93ba0 dc28eaa0 dc198800 00000000 >> 000005c0 00000002 00000000 >> GPR08: 00001032 c08c2c2c 00000000 c08c1ab0 28228424 >> 0049ce6c e2287b5c 00000000 >> GPR16: c06974dc 00000007 e2284384 00000001 dec9852c >> e2282610 00000000 000a0000 >> GPR24: c07c9d60 c07c9d2c dc19880c 00000000 dec93bb8 >> 00000000 c0931a84 dc198800 >> [ 657.135405] NIP [c039e6ec] put_fb_info+0x18/0x68 >> [ 657.135411] LR [c039e834] do_unregister_framebuffer+0xf8/0x148 >> [ 657.135413] Call Trace: >> [ 657.135419] [dec93bb0] [c039e834] do_unregister_framebuffer+0xf8/0x148 >> [ 657.135425] [dec93be0] [c039ea1c] >> do_remove_conflicting_framebuffers+0x198/0x1b8 >> [ 657.135431] [dec93c30] [c039ea84] remove_conflicting_framebuffers+0x48/0x6c >> [ 657.135474] [dec93c50] [e2274d6c] >> radeonfb_pci_register+0x184/0x1838 [radeonfb] >> [ 657.135481] [dec93cb0] [c037e9fc] pci_device_probe+0x110/0x180 >> [ 657.135492] [dec93ce0] [c045be70] driver_probe_device+0x378/0x4a0 >> [ 657.135497] [dec93d10] [c045c0ac] __driver_attach+0x114/0x118 >> [ 657.135503] [dec93d30] [c04593dc] bus_for_each_dev+0x74/0xc0 >> [ 657.135508] [dec93d60] [c045acd4] bus_add_driver+0x18c/0x2a0 >> [ 657.135515] [dec93d80] [c045ce3c] driver_register+0x94/0x13c >> [ 657.135524] [dec93d90] [c0004af4] do_one_initcall+0x4c/0x178 >> [ 657.135536] [dec93df0] [c00ced18] do_init_module+0x70/0x1ec >> [ 657.135542] [dec93e10] [c00cdcb0] load_module+0x20d8/0x26b8 >> [ 657.135548] [dec93ec0] [c00ce500] SyS_finit_module+0xc4/0x120 >> [ 657.135555] [dec93f40] [c00181cc] ret_from_syscall+0x0/0x40 >> [ 657.135562] --- interrupt: c01 at 0x34d450 >> LR = 0x476108 >> [ 657.135566] Instruction dump: >> [ 657.135572] 80010014 38210010 7c0803a6 4e800020 38600000 4e800020 >> 7c0802a6 90010004 >> [ 657.135582] 60000000 9421fff0 7c0802a6 90010014 <0fe00000> 7d401828 >> 314affff 7d40192d >> [ 657.135593] ---[ end trace e0bf4192eb1c4f63 ]--- >> [ 657.135613] device: 'vtcon1': device_unregister >> [ 657.135644] PM: Removing info for No Bus:vtcon1 >> >> >> Full dmesg: >> https://people.debian.org/~malat/dmesg_radeonfb.txt >> >> Does that help at all? the call stack does not make much sense to me. >> I am accessing the Mac Mini over ssh. > > Thank you, it helps. > > User-space is holding reference on the /dev/fb0 and old fb_info > (from offb) while offb is being replaced by radeonfb (this is > why ->fb_destroy is never called). You may try checking with > lsof command to see what is holding /dev/fb0 open.. Right, I totally missed that X was running: $ sudo lsof /dev/fb0 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME Xorg 469 root mem CHR 29,0 6500 /dev/fb0 Xorg 469 root 12u CHR 29,0 0t0 6500 /dev/fb0 so I simply: $ dmesg > before_xdm_stop $ sudo service xdm stop $ dmesg > after_xdm_stop $ sudo lsof /dev/fb0 -> nothing And I can verify in dmesg the call to put_fb_info: $ diff -u before_xdm_stop after_xdm_stop @@ -1589,3 +1589,31 @@ [ 19.650088] gem 0002:20:0f.0 eth0: Link is up at 100 Mbps, full-duplex [ 19.650211] gem 0002:20:0f.0 eth0: Pause is disabled [ 19.650245] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready +[ 38.545478] WARNING: CPU: 0 PID: 468 at drivers/video/fbdev/core/fbmem.c:77 put_fb_info+0x18/0x68 +[ 38.545772] Modules linked in: uinput arc4 b43 bcma mac80211 snd_aoa_codec_toonie snd_aoa_fabric_layout snd_aoa sha256_generic cfg80211 evdev sg snd_aoa_i2sbus snd_aoa_soundbus snd_pcm snd_timer snd soundcore ssb usb_storage autofs4 ext4 crc16 mbcache jbd2 fscrypto usbhid ohci_pci ehci_pci ohci_hcd ehci_hcd sungem firewire_ohci sungem_phy firewire_core crc_itu_t sr_mod usbcore cdrom sd_mod nls_base usb_common +[ 38.546894] CPU: 0 PID: 468 Comm: Xorg Tainted: G W 4.15.0+ #31 +[ 38.547103] NIP: c03083ec LR: c0308bb0 CTR: c0308b48 +[ 38.547252] REGS: de661dc0 TRAP: 0700 Tainted: G W (4.15.0+) +[ 38.547459] MSR: 00029032 CR: 22002222 XER: 20000000 +[ 38.547661] + GPR00: c0308bb0 de661e70 ddd108c0 dee02c00 de0febe0 de0febe8 00000001 ddd108c0 + GPR08: 00000000 c07b0a40 00000000 df501e10 22002428 007e0ff4 00000000 00000000 + GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 + GPR24: ddd108c0 de0febe8 dede1c10 df30bbb0 df501e10 dede1c10 dee02c10 dee02c00 +[ 38.548684] NIP [c03083ec] put_fb_info+0x18/0x68 +[ 38.548821] LR [c0308bb0] fb_release+0x68/0x80 +[ 38.548951] Call Trace: +[ 38.549026] [de661e70] [dede1c10] 0xdede1c10 (unreliable) +[ 38.549186] [de661e80] [c0308bb0] fb_release+0x68/0x80 +[ 38.549344] [de661e90] [c01c1198] __fput+0xac/0x20c +[ 38.553889] [de661ec0] [c0062140] task_work_run+0xc0/0xe8 +[ 38.558437] [de661ee0] [c0048918] do_exit+0x268/0x964 +[ 38.562960] [de661f20] [c00490b4] do_group_exit+0x4c/0xb0 +[ 38.567400] [de661f30] [c0049138] __wake_up_parent+0x0/0x3c +[ 38.571740] [de661f40] [c00151bc] ret_from_syscall+0x0/0x38 +[ 38.575965] --- interrupt: c01 at 0xb794a778 + LR = 0xb794a748 +[ 38.584039] Instruction dump: +[ 38.587878] 80010014 38210010 7c0803a6 4e800020 38600000 4e800020 7c0802a6 90010004 +[ 38.595537] 60000000 9421fff0 7c0802a6 90010014 <0fe00000> 7d401828 314affff 7d40192d +[ 38.603316] ---[ end trace ee2e036160cab00c ]--- Now with your WARN_ON patch and xdm service stopped, here is what I get: https://people.debian.org/~malat/full_xdm_stop_offb_without.log You'll see that modprobe to radeonfb still fails. If you now compare with the patch (v4) applied (+ WARN_ON and xdm service stopped): https://people.debian.org/~malat/full_xdm_stop_offb_with.log You'll see a printk INFO for the call to offb_destroy: ... [ 48.025983] MM calling offb_destroy ... offb_destroy is called too late, which explains the failure for loading radeonfb without the patch. -M >> For reference, the patch I used is: >> https://github.com/malaterre/linux/commit/89fd7d4438c5200a1a4fcba1d60dd701fda4f40e.patch >> >> >> >> >> Signed-off-by: Mathieu Malaterre >> >> >> Link: https://bugs.debian.org/826629#57 >> >> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=119741 >> >> >> Suggested-by: Lennart Sorensen >> >> >> --- >> >> >> v2: Only fails when CONFIG_PCC is not set >> >> >> v3: Only fails when CONFIG_FB_OF is not set, CONFIG_PCC was too broad. Since the conflicts in region is due to OFfb explicitly refers to it. >> >> > >> >> > It seems that there may still be configurations when this is >> >> > incorrect -> when offb drives primary (non-radeon) card and radeonfb >> >> > drives secondary (radeon) card.. >> >> > >> >> >> drivers/video/fbdev/aty/radeon_base.c | 26 ++++++++++++++++++++++++++ >> >> >> 1 file changed, 26 insertions(+) >> >> >> >> >> >> diff --git a/drivers/video/fbdev/aty/radeon_base.c b/drivers/video/fbdev/aty/radeon_base.c >> >> >> index 4d77daeecf99..221879196531 100644 >> >> >> --- a/drivers/video/fbdev/aty/radeon_base.c >> >> >> +++ b/drivers/video/fbdev/aty/radeon_base.c >> >> >> @@ -2259,6 +2259,22 @@ static const struct bin_attribute edid2_attr = { >> >> >> .read = radeon_show_edid2, >> >> >> }; >> >> >> >> >> >> +static int radeon_kick_out_firmware_fb(struct pci_dev *pdev) >> >> >> +{ >> >> >> + struct apertures_struct *ap; >> >> >> + >> >> >> + ap = alloc_apertures(1); >> >> >> + if (!ap) >> >> >> + return -ENOMEM; >> >> >> + >> >> >> + ap->ranges[0].base = pci_resource_start(pdev, 0); >> >> >> + ap->ranges[0].size = pci_resource_len(pdev, 0); >> >> >> + >> >> >> + remove_conflicting_framebuffers(ap, KBUILD_MODNAME, false); >> >> >> + kfree(ap); >> >> >> + >> >> >> + return 0; >> >> >> +} >> >> >> >> >> >> static int radeonfb_pci_register(struct pci_dev *pdev, >> >> >> const struct pci_device_id *ent) >> >> >> @@ -2312,19 +2328,27 @@ static int radeonfb_pci_register(struct pci_dev *pdev, >> >> >> rinfo->fb_base_phys = pci_resource_start (pdev, 0); >> >> >> rinfo->mmio_base_phys = pci_resource_start (pdev, 2); >> >> >> >> >> >> + ret = radeon_kick_out_firmware_fb(pdev); >> >> >> + if (ret) >> >> >> + return ret; >> >> >> + >> >> >> /* request the mem regions */ >> >> >> ret = pci_request_region(pdev, 0, "radeonfb framebuffer"); >> >> >> if (ret < 0) { >> >> >> +#ifndef CONFIG_FB_OF >> >> >> printk( KERN_ERR "radeonfb (%s): cannot request region 0.\n", >> >> >> pci_name(rinfo->pdev)); >> >> >> goto err_release_fb; >> >> >> +#endif >> >> >> } >> >> >> >> >> >> ret = pci_request_region(pdev, 2, "radeonfb mmio"); >> >> >> if (ret < 0) { >> >> >> +#ifndef CONFIG_FB_OF >> >> >> printk( KERN_ERR "radeonfb (%s): cannot request region 2.\n", >> >> >> pci_name(rinfo->pdev)); >> >> >> goto err_release_pci0; >> >> >> +#endif >> >> >> } >> >> >> >> >> >> /* map the regions */ >> >> >> @@ -2509,10 +2533,12 @@ static int radeonfb_pci_register(struct pci_dev *pdev, >> >> >> iounmap(rinfo->mmio_base); >> >> >> err_release_pci2: >> >> >> pci_release_region(pdev, 2); >> >> >> +#ifndef CONFIG_FB_OF >> >> >> err_release_pci0: >> >> >> pci_release_region(pdev, 0); >> >> >> err_release_fb: >> >> >> framebuffer_release(info); >> >> >> +#endif >> >> >> err_disable: >> >> >> err_out: >> >> >> return ret; >> >> > > > Best regards, > -- > Bartlomiej Zolnierkiewicz > Samsung R&D Institute Poland > Samsung Electronics >