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Date: Mon, 8 Jun 2020 19:31:47 -0700 (PDT) From: David Rientjes <rientjes@...gle.com> To: "Alex Xu (Hello71)" <alex_y_xu@...oo.ca> cc: Christoph Hellwig <hch@....de>, alsa-devel@...a-project.org, bp@...en8.de, hch@...radead.org, hpa@...or.com, linux-kernel@...r.kernel.org, mingo@...hat.com, Pavel Machek <pavel@....cz>, perex@...ex.cz, tglx@...utronix.de, tiwai@...e.com, x86@...nel.org Subject: Re: next-0519 on thinkpad x60: sound related? window manager crash On Mon, 8 Jun 2020, Alex Xu (Hello71) wrote: > Excerpts from Christoph Hellwig's message of June 8, 2020 2:19 am: > > Can you do a listing using gdb where this happens? > > > > gdb vmlinux > > > > l *(snd_pcm_hw_params+0x3f3) > > > > ? > > > > (gdb) l *(snd_pcm_hw_params+0x3f3) > 0xffffffff817efc85 is in snd_pcm_hw_params (.../linux/sound/core/pcm_native.c:749). > 744 while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size) > 745 runtime->boundary *= 2; > 746 > 747 /* clear the buffer for avoiding possible kernel info leaks */ > 748 if (runtime->dma_area && !substream->ops->copy_user) > 749 memset(runtime->dma_area, 0, runtime->dma_bytes); > 750 > 751 snd_pcm_timer_resolution_change(substream); > 752 snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP); > 753 > Working theory is that CONFIG_DMA_NONCOHERENT_MMAP getting set is causing the error_code in the page fault path. Debugging with Alex off-thread we found that dma_{alloc,free}_from_pool() are not getting called from the new code in dma_direct_{alloc,free}_pages() and he has not enabled mem_encrypt. So the issue is related to setting CONFIG_DMA_COHERENT_POOL, and not anything else related to AMD SME. He has a patch to try out, but I wanted to update the thread in case there are other ideas to try other than selecting CONFIG_DMA_NONCOHERENT_MMAP only when CONFIG_DMA_REMAP is set (and not CONFIG_DMA_COHERENT_POOL).
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