From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794591023; b=nWUb1nGQDBeo1NQncXZX/1130etpLuYlpqT+WNxT7WI7Z7aeL1tXvzH6sbMz4bsqMlZg lbvpqaWLbY25fPKlsHO42R+MJeuadGJ4PPl3i2ZRQFGxcA2/BGGAdjzvy3MPCdiKsIrI8 +j3AC1dN0bvdYT+0lxDo9qGSxBYipXTtP7hOH0Ps+H0lDk97zZYmHlTv/21w+AxXM82Lr C00AduMfiN2gMtPGgJ6NYUNNqHEkVMVZ0o7Yi9rk8+QcJ1OqLWhOzQ3z7DUtctHD3t98i tQiW20rehyp/JagW7qBzRTztC9fkfYIyf8c+chj26lGnxwwAwZqeAt0ntMdia2XL9EA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794591023; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=tEUD2m98Z+sITw9Og0/Atrw3WLkhSpQESe2dfizlzQI=; b=sbIeSE5X7bdLyaNOHKYyeSGQ4fYr7WeHuaBFANE/EgX/sstwHAr+mP+DLV+WPpp23SFr EqHuSt8CEQVv3Eb2UFw92dXLOn1FNGRsZPKDGIiiPVjcl2abGDYiUXwEgLE06ERlLTzwM e533p9qErk7fZvLn9ynBlKHY9u3J1LfyCaSbHlyBUOhK3kvLMtxkAMQX2V1XjccZNZoRS qDT5Mb95x8CjIEIMpUSE9p71KHzUOL6r24ENQh5GFO4m2cHNh52K6NY09QLNPQIgQafZh PkPL2xcinDMMCK8SncV/X4eXmxTOx8f4B21MtmO6nNNKWFAtSfo2WerWjpWDZqU3GAA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=P1qj0zk+; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B47506070F3E; Fri, 13 Nov 2026 17:30:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=P1qj0zk+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60A2C1F000C4; Fri, 13 Nov 2026 17:30:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794591023; bh=tEUD2m98Z+sITw9Og0/Atrw3WLkhSpQESe2dfizlzQI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=P1qj0zk+dVvV/BoMLUMSPWc0srsk92V02ffNGd5t3Lh1ZpXfj+jZlcKpBuh5YNBpi OsU0qEeAsqYYitCG+F6JpjSCbX0wI/JAIJBMCNmYTq8TnW7J3bkdhvlC5AYVV96YBm Fv+c8HmYicNH4jqmLqNbVUAfsIq6bR4Gey2sJ2s8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Iago Toral Quiroga , =?UTF-8?q?Ma=C3=ADra=20Canal?= , Sasha Levin Subject: [PATCH 6.12 189/670] drm/vc4: Publish the output fence outside of job_lock Date: Fri, 13 Nov 2026 10:45:53 -0500 Message-ID: <20261113153818.419155624@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Maíra Canal [ Upstream commit 9ee552a42c3905b4547e83173d46413137ec329a ] job_lock is taken by the V3D interrupt handler, so nesting an IRQ-unsafe lock under it creates an inversion. drm_syncobj_replace_fence() takes drm_syncobj::lock, which other paths acquire with interrupts enabled. For example, a thread interrupted while holding it blocks the handler on job_lock, and the handler can only make progress once the submit path releases job_lock, which it cannot do while waiting for drm_syncobj::lock. This is reported by lockdep: [ 188.139076] ======================================================== [ 188.139086] WARNING: possible irq lock inversion dependency detected [ 188.139096] 7.3.0-rc3-00067-gc4f3feeaf60f #67 Tainted: G C [ 188.139108] -------------------------------------------------------- [ 188.139116] swapper/0/0 just changed the state of lock: [ 188.139125] ffff0000054f8ff8 (&vc4->job_lock){-...}-{3:3}, at: vc4_irq+0xa8/0x28c [vc4] [ 188.139234] but this lock took another, HARDIRQ-unsafe lock in the past: [ 188.139242] (&syncobj->lock){+.+.}-{3:3} [ 188.139256] and interrupts could create inverse lock ordering between them. [ 188.139267] other info that might help us debug this: [ 188.139275] Possible interrupt unsafe locking scenario: [ 188.139284] CPU0 CPU1 [ 188.139291] ---- ---- [ 188.139299] lock(&syncobj->lock); [ 188.139312] local_irq_disable(); [ 188.139320] lock(&vc4->job_lock); [ 188.139335] lock(&syncobj->lock); [ 188.139350] [ 188.139358] lock(&vc4->job_lock); [ 188.139372] *** DEADLOCK *** Hand the fence over after job_lock is dropped. The job can complete and drop exec->fence in that window, so take a reference first and publish through the local pointer, as exec may already be gone. Cc: stable@vger.kernel.org Fixes: e84fcb95e074 ("drm/vc4: Export fence through syncobj") Reviewed-by: Iago Toral Quiroga Link: https://patch.msgid.link/20261004-vc4-misc-fixes-v1-1-b763df9e33e1@igalia.com Signed-off-by: Maíra Canal Signed-off-by: Sasha Levin --- drivers/gpu/drm/vc4/vc4_gem.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c index bec799d41d622..f7df302e5c671 100644 --- a/drivers/gpu/drm/vc4/vc4_gem.c +++ b/drivers/gpu/drm/vc4/vc4_gem.c @@ -706,8 +706,11 @@ vc4_queue_submit(struct drm_device *dev, struct vc4_exec_info *exec, fence->seqno = exec->seqno; exec->fence = &fence->base; + /* The job can complete and drop exec->fence as soon as job_lock is + * released, so hold our own reference. + */ if (out_sync) - drm_syncobj_replace_fence(out_sync, exec->fence); + dma_fence_get(&fence->base); vc4_update_bo_seqnos(exec, seqno); @@ -729,6 +732,11 @@ vc4_queue_submit(struct drm_device *dev, struct vc4_exec_info *exec, spin_unlock_irqrestore(&vc4->job_lock, irqflags); + if (out_sync) { + drm_syncobj_replace_fence(out_sync, &fence->base); + dma_fence_put(&fence->base); + } + return 0; } -- 2.53.0