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[23.128.96.18]) by mx.google.com with ESMTP id r10si7368513jap.64.2021.08.20.12.24.54; Fri, 20 Aug 2021 12:25:05 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@suse.de header.s=susede2_rsa header.b=w715AXDN; dkim=neutral (no key) header.i=@suse.de; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=suse.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238069AbhHTTYe (ORCPT + 99 others); Fri, 20 Aug 2021 15:24:34 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:38586 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229923AbhHTTYd (ORCPT ); Fri, 20 Aug 2021 15:24:33 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id BC5512016A; Fri, 20 Aug 2021 19:23:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1629487433; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=J/ZTHYspJWems3grCDvjCH9V3Hhhi4avlqSwNlHDseY=; b=w715AXDNp3TIRo7tdKvLhrjp59r1bQccQ1zHmXeFvTGAP9S90SGPYX8yANzkrJVdT+dBTI FDHMWAcwUI1kA/5bqDad5ERYL9B32IMDohhBSGMvzigj7h+aDi4IwKhEUQexe75ZD8aNuy 9uff1GLGaUIN8OrT8YzJapgrItfqMCo= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1629487433; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=J/ZTHYspJWems3grCDvjCH9V3Hhhi4avlqSwNlHDseY=; b=3dduTyFnRRIIKMQglkFUGeRkDtPYvK25MBhk7tvpM1DR1tm08KlCLiqDtrNdUizOWaBZoO vh686/xKzNjcXuDw== Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id 5600D13BE5; Fri, 20 Aug 2021 19:23:53 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id 2dEQE0kBIGGIXgAAGKfGzw (envelope-from ); Fri, 20 Aug 2021 19:23:53 +0000 To: syzbot , airlied@linux.ie, christian.koenig@amd.com, daniel.vetter@ffwll.ch, daniel.vetter@intel.com, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, linaro-mm-sig-owner@lists.linaro.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, maarten.lankhorst@linux.intel.com, melissa.srw@gmail.com, mripard@kernel.org, sumit.semwal@linaro.org, syzkaller-bugs@googlegroups.com References: <00000000000047b52b05c9ff8d0b@google.com> From: Thomas Zimmermann Subject: Re: [syzbot] WARNING in drm_gem_shmem_vm_open Message-ID: Date: Fri, 20 Aug 2021 21:23:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <00000000000047b52b05c9ff8d0b@google.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="9BSk7OnrvXIspcoyXpuha4Szaal3Vonnh" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --9BSk7OnrvXIspcoyXpuha4Szaal3Vonnh Content-Type: multipart/mixed; boundary="RFSfHUaXVAmGRzteq89QyZAcdgd27yXDG"; protected-headers="v1" From: Thomas Zimmermann To: syzbot , airlied@linux.ie, christian.koenig@amd.com, daniel.vetter@ffwll.ch, daniel.vetter@intel.com, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, linaro-mm-sig-owner@lists.linaro.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, maarten.lankhorst@linux.intel.com, melissa.srw@gmail.com, mripard@kernel.org, sumit.semwal@linaro.org, syzkaller-bugs@googlegroups.com Message-ID: Subject: Re: [syzbot] WARNING in drm_gem_shmem_vm_open References: <00000000000047b52b05c9ff8d0b@google.com> In-Reply-To: <00000000000047b52b05c9ff8d0b@google.com> --RFSfHUaXVAmGRzteq89QyZAcdgd27yXDG Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Am 20.08.21 um 17:45 schrieb syzbot: > syzbot has bisected this issue to: Good bot! >=20 > commit ea40d7857d5250e5400f38c69ef9e17321e9c4a2 > Author: Daniel Vetter > Date: Fri Oct 9 23:21:56 2020 +0000 >=20 > drm/vkms: fbdev emulation support Here's a guess. GEM SHMEM + fbdev emulation requires that=20 (drm_mode_config.prefer_shadow_fbdev =3D true). Otherwise, deferred I/O=20 and SHMEM conflict over the use of page flags IIRC. From a quick grep, vkms doesn't set prefer_shadow_fbdev and an alarming = amount of SHMEM-based drivers don't do either. Best regards Thomas >=20 > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=3D11c31d55= 300000 > start commit: 614cb2751d31 Merge tag 'trace-v5.14-rc6' of git://git.k= ern.. > git tree: upstream > final oops: https://syzkaller.appspot.com/x/report.txt?x=3D13c31d55= 300000 > console output: https://syzkaller.appspot.com/x/log.txt?x=3D15c31d55300= 000 > kernel config: https://syzkaller.appspot.com/x/.config?x=3D96f06022032= 50753 > dashboard link: https://syzkaller.appspot.com/bug?extid=3D91525b2bd4b5d= ff71619 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D122bce0e3= 00000 >=20 > Reported-by: syzbot+91525b2bd4b5dff71619@syzkaller.appspotmail.com > Fixes: ea40d7857d52 ("drm/vkms: fbdev emulation support") >=20 > For information about bisection process see: https://goo.gl/tpsmEJ#bise= ction >=20 --=20 Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany (HRB 36809, AG N=C3=BCrnberg) Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer --RFSfHUaXVAmGRzteq89QyZAcdgd27yXDG-- --9BSk7OnrvXIspcoyXpuha4Szaal3Vonnh Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- wsF5BAABCAAjFiEExndm/fpuMUdwYFFolh/E3EQov+AFAmEgAUgFAwAAAAAACgkQlh/E3EQov+Ca QhAAkZ31x5M00jNSVFt6zSFPz7zsmP1+pIfZD9wsS8TkIJGxUsHyfbh9a/eIijkh/e8zNqQ9JP1P HOscLUH/AgY9d+/RCrU062w/5zKJEOhodrt+9FzVqGeavOM3csDR5ll6bPv2oo0eSpnttEJ2w6SG 1urAbMBvUbIRvWN+vmdYIqp4ezHHj7izBuRoFeRWQNn7t8AQjaqnduIhip9takLa2nLd2zIOYAev vVdgtw9+JI/2ZJCnbFedn/CvDJ4A8VPLfeSQcgG8Ksqw+VHjRBrd5sS+Z7K9RFTNqi5Ec7klHdei JrnvVmLWoezYdjoDjVWLINuEk2r7L6GAhoF0oDhZq1kVv7K33xfDIdQB2p8JqTY9o22Rthjq0Kkc zg5vhhr/CBZ2H7gACKGybG86UqcO5e0z2PVlmlZvVRdgC5x0ZGGxMe79e2GVwUbCuDBepAwet/fq XbdBZ1JmDxdRnODXB7A6LvqDyDiCjAKI4pcTB/9OjUZ9CUSk1XXc52WJV2btzfGPSDaSMRRg6l6C eFKIlD/Gk9kXHttN3F6+OZeK46oFRodhgQ2ooaf1jRetNa1xd6d+b8m6UFerDQplYGiR1F3jnwvv 3GOzP8qg0PP9tgr9/7ozH50m1IUEcNuX2iCVwVs/dkuBYH+OIQbZtmZqizDWKx3DvNg+341m4EA4 kvA= =gavY -----END PGP SIGNATURE----- --9BSk7OnrvXIspcoyXpuha4Szaal3Vonnh--