From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02BE13822A8 for ; Fri, 3 Jul 2026 09:00:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783069243; cv=none; b=KX1IikD8gn7a1rDKDGPx+yGaueGsACDq33d9ntyePDGJVtV8WBvY+st/YtakFrzub5VyWmrDqXn2BsexJcQSKGqcl3p9XtajUnD8WICclSnJzemR3ffhdb18xHPkBq1FdV3AuVeZU2h1X3qezvT16jO/biBWbLW3m6r9U/xwEZM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783069243; c=relaxed/simple; bh=sSKvjKd8YM02ge9arLC/u/3pQmJcQgf7zP1scKQhZR4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fioDw8fact2GZvKG8cSphd3gahdLtWf3teFCRObbT4rws979KwOsjlP2cRqPUAeWvv7GzoqGex1/G7ltq9cP3QfZIvkY/jJomCK+CMAC6+GxbD5dUH0coe/sPYAEaTcPnSD/LrLRmCq/6vmLwJMNoK8AWiEJMjvKaUo7Ps3v0h4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=BMPZSztj; arc=none smtp.client-ip=209.85.128.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BMPZSztj" Received: by mail-wm1-f45.google.com with SMTP id 5b1f17b1804b1-493b77b150aso2391685e9.2 for ; Fri, 03 Jul 2026 02:00:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1783069240; x=1783674040; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :content-type:mime-version:references:message-id:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to:content-type; bh=17LXBsqJWXMdbXOj6D6oFUX+lcM/gu/+EbDoLE3v86Q=; b=BMPZSztjRDh3GcSVlkFzWK0vPon1J2ab5xRcjLlzBRg0pqXk1YQwbEQ/fw/atU+Gag MkxVuW4oG6X/Lp9zkgMi0e75YmLnxVRbtEOp5ba3XOXDyGcn3+sKsFDO+I219bYXKwa7 vxm8qMr409Gjgj9HuBBgsxs03dZSNnZ8bAU/LqNfLl8aXVZRY8nASf2jXoo+D/JdhQGn by0kIFoEPZbF3DaDRd5OIldgZ0q3d7E29IChjMkfTVq+2EjTY9pysuyFHBz9EYg46utV mzjhFT4rsXyaPOjnBkkQdxmvlosJ4TjcLpmXuEfuS8UiJ5as3qo5xOy32pp+lTS0PZgg s6QA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783069240; x=1783674040; h=in-reply-to:content-transfer-encoding:content-disposition :content-type:mime-version:references:message-id:subject:cc:to:from :date:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=17LXBsqJWXMdbXOj6D6oFUX+lcM/gu/+EbDoLE3v86Q=; b=o+Izo8J8S3EGyRaMp9NCE/ti+Bfr9KQVFjSRmw+2+Dw6NzgZayJBKchm3zgXToZq+b Qo36sS+sp5vCgdOmuyG3bUvpSwuVzR4n9DcrLPuMuzeL7b4lUJICdzynLNGyPJlxUYjs hmkyXadzyVsN8reLkBuSlj+ZAeImJVGx4zq3DtBfPWq39DSsm9VAmSCsRruEA3S/tWDi JygzkxTuSj1R//YhTrf2/VgLGTG9B/u4y+m4Om/LBLpUsK4DYcXnCCfhkAiX7YFozWvp KarPZ3IYia11Ed9B6zipsssI/L1Iry0W7uB6/Ot3aOj+3rQiauF0snowTMrdEtG8O4Gi yqrQ== X-Forwarded-Encrypted: i=1; AFNElJ93EhSE9X5AeyjuCAwE7Aljd7Z4HbPQfpJLkdX2O4GgXEvrLUY3tFZsKgmIpCp3xCeSOvLsHo3MldUTqyE=@vger.kernel.org X-Gm-Message-State: AOJu0YwKrbUVzTFRNMb8SNeTYZ3ie1LcY2wEh3g6VFPy8bhqdtbDhbnC NT7vs9kACXU1YtWKUcrTgTiGMbv/x0rV32gDmC6AqNinvY+2yKrCz8mz X-Gm-Gg: AfdE7clCrzi8/iyuqRmgHrtAjAXS1R9jzoHC9D1O9iC6FLuiP5E3y8t3OkEDNfxcVNd /n+TUxHUYSVd41FnAKrjANrgl+/5IghNw3gpckyHpxBiYIdtColbNEnxdhTDoEMOrViOK5E3JSk c/GuAouwuQ86iQOYkcwvQkKD/Rpztxq4LV5mpYLH4fWvv3RgXjvgYlnsGICFO+26TOQtEorCAly nB6TXcVpq+B5uc7qi9+HQ7dyJy9voGor5gCDVjJHe5xMcV8pWc2exbQntpgs7aUY30LaC+u3cTn NKFRgq1cf9IDoJAfeuAPbbWA6KZ61v9hMSE1/a16wcT4KJebT7tHz65YAoJw4MNwAOZfXMsEziG QZWGEEbU2vaVoqt9/D5Ps5lJNZyOmE1ppIsQYJUmGkBZt0qc68l13cAehGmdclxC4yp+dGZKQkD 6s+6WtU4W436w= X-Received: by 2002:a05:600c:60a:b0:490:e19b:bd99 with SMTP id 5b1f17b1804b1-493c3cf49f7mr80184765e9.30.1783069240081; Fri, 03 Jul 2026 02:00:40 -0700 (PDT) Received: from fedora ([94.73.45.171]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-493bef17c82sm129905895e9.1.2026.07.03.02.00.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Jul 2026 02:00:39 -0700 (PDT) Date: Fri, 3 Jul 2026 11:00:37 +0200 From: =?iso-8859-1?Q?Jos=E9_Exp=F3sito?= To: Thomas Zimmermann Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@gmail.com, simona@ffwll.ch, boris.brezillon@collabora.com, kees@kernel.org Subject: Re: [PATCH 0/2] drm/tests: shmem: Fix intermittent DMA overflow on ppc64le/s390x Message-ID: References: <20260703063517.6346-1-jose.exposito89@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hi Thomas, Thanks for your review. On Fri, Jul 03, 2026 at 08:53:30AM +0200, Thomas Zimmermann wrote: > Hi > > Am 03.07.26 um 08:34 schrieb José Expósito: > > Two drm_gem_shmem KUnit tests, drm_gem_shmem_test_get_pages_sgt() and > > drm_gem_shmem_test_purge(), intermittently fail on ppc64le and s390x CI > > with a DMA address overflow warning followed by -EIO: > > > > DMA addr 0x00000001130b0000+65536 overflow (mask ffffffff, bus limit 0). > > Expected sgt is not error, but is: -5 > > > > Both tests call `drm_gem_shmem_get_pages_sgt()`, which internally pins > > backing pages and DMA-maps them via `dma_map_sgtable()`. The DMA mapping > > path is: > > > > drm_gem_shmem_test_purge() > > drm_gem_shmem_get_pages_sgt() > > drm_gem_shmem_get_pages_sgt_locked() [drm_gem_shmem_helper.c] > > dma_map_sgtable() [mapping.c] > > __dma_map_sg_attrs() > > dma_direct_map_sg() [direct.c] > > dma_direct_map_phys() [kernel/dma/direct.h] > > dma_capable() Checks addr against DMA mask > > -> FAILS: addr > 0xFFFFFFFF > > > > KUnit devices are initialized with a 32-bit DMA mask > > (`DMA_BIT_MASK(32)`) in `lib/kunit/device.c`. On systems where the kernel > > allocates backing pages at physical addresses above 4GB, `dma_capable()` > > returns false because the address exceeds the 32-bit mask. The `dma_set_mask()` > > function updates `*dev->dma_mask` to the given value; setting it to > > `DMA_BIT_MASK(64)` allows any physical address to pass the check. > > > > The failure is intermittent because pages may or may not be allocated > > above 4GB on any given run depend on memory pressure. > > > > A third test in the same suite, `drm_gem_shmem_test_obj_create_private`, > > already calls `dma_set_mask(drm_dev->dev, DMA_BIT_MASK(64))` before its > > DMA mapping. This series applies the same fix to the two remaining tests. > > Instead of doing whack-a-mole, is it possible to move the existing fix from > drm_gem_shmem_test_obj_create_private() to _test_init at [1] ? The DMA mask > would then be the same on all tests. [1] https://elixir.bootlin.com/linux/v7.1.2/source/drivers/gpu/drm/tests/drm_gem_shmem_test.c#L359 Yes, I think it is possible. However, this is an intermittent failure that I couldn't reproduce locally and I tried to reduce as much as possible the risk of regression limitting the change to the 2 affected tests. I'm afraid I don't have enough knoledge about GEM's internals to know if moving the fix to the init function could introduce unwanted side-effects in the other tests. If you think it'd be safe, I'll trust you and move it. Jose PS - Next week I'll be away from keyboard, so any change would need to wait a bit > Best regards Thomas > > > > José Expósito (2): > > drm/tests: shmem: Set DMA mask to 64-bit in > > drm_gem_shmem_test_get_pages_sgt > > drm/tests: shmem: Set DMA mask to 64-bit in drm_gem_shmem_test_purge > > > > drivers/gpu/drm/tests/drm_gem_shmem_test.c | 9 ++++++++- > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > -- > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com > GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg) > >