From: Jason Gunthorpe <jgg@ziepe.ca> To: christian.koenig@amd.com, akpm@linux-foundation.org, sumit.semwal@linaro.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: Changing vma->vm_file in dma_buf_mmap() Date: Wed, 16 Sep 2020 11:07:10 -0300 [thread overview] Message-ID: <20200916140710.GA8409@ziepe.ca> (raw) In-Reply-To: <20200916095359.GD438822@phenom.ffwll.local> On Wed, Sep 16, 2020 at 11:53:59AM +0200, Daniel Vetter wrote: > But within the driver, we generally need thousands of these, and that > tends to bring fd exhaustion problems with it. That's why all the private > buffer objects which aren't shared with other process or other drivers are > handles only valid for a specific fd instance of the drm chardev (each > open gets their own namespace), and only for ioctls done on that chardev. > And for mmap we assign fake (but unique across all open fd on it) offsets > within the overall chardev. Hence all the pgoff mangling and re-mangling. Are they still unique struct files? Just without a fdno? > Hence why we'd like to be able to forward aliasing mappings and adjust the > file and pgoff, while hopefully everything keeps working. I thought this > would work, but Christian noticed it doesn't really. It seems reasonable to me that the dma buf should be the owner of the VMA, otherwise like you say, there is a big mess attaching the custom vma ops and what not to the proper dma buf. I don't see anything obviously against this in mmap_region() - why did Chritian notice it doesn't really work? Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@ziepe.ca> To: christian.koenig@amd.com, akpm@linux-foundation.org, sumit.semwal@linaro.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: Changing vma->vm_file in dma_buf_mmap() Date: Wed, 16 Sep 2020 11:07:10 -0300 [thread overview] Message-ID: <20200916140710.GA8409@ziepe.ca> (raw) In-Reply-To: <20200916095359.GD438822@phenom.ffwll.local> On Wed, Sep 16, 2020 at 11:53:59AM +0200, Daniel Vetter wrote: > But within the driver, we generally need thousands of these, and that > tends to bring fd exhaustion problems with it. That's why all the private > buffer objects which aren't shared with other process or other drivers are > handles only valid for a specific fd instance of the drm chardev (each > open gets their own namespace), and only for ioctls done on that chardev. > And for mmap we assign fake (but unique across all open fd on it) offsets > within the overall chardev. Hence all the pgoff mangling and re-mangling. Are they still unique struct files? Just without a fdno? > Hence why we'd like to be able to forward aliasing mappings and adjust the > file and pgoff, while hopefully everything keeps working. I thought this > would work, but Christian noticed it doesn't really. It seems reasonable to me that the dma buf should be the owner of the VMA, otherwise like you say, there is a big mess attaching the custom vma ops and what not to the proper dma buf. I don't see anything obviously against this in mmap_region() - why did Chritian notice it doesn't really work? Jason _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-09-16 17:05 UTC|newest] Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-14 13:29 Changing vma->vm_file in dma_buf_mmap() Christian König 2020-09-14 13:29 ` Christian König 2020-09-14 13:29 ` [PATCH 1/2] drm/shmem-helpers: revert "Redirect mmap for imported dma-buf" Christian König 2020-09-14 13:29 ` Christian König 2020-09-15 10:39 ` Daniel Vetter 2020-09-15 10:39 ` Daniel Vetter 2020-09-15 10:39 ` Daniel Vetter 2020-09-15 11:03 ` Christian König 2020-09-15 11:03 ` Christian König 2020-09-15 11:03 ` Christian König 2020-09-15 11:07 ` Daniel Vetter 2020-09-15 11:07 ` Daniel Vetter 2020-09-15 11:07 ` Daniel Vetter 2020-09-14 13:29 ` [PATCH 2/2] mm: introduce vma_set_file function Christian König 2020-09-14 13:29 ` Christian König 2020-09-15 9:19 ` kernel test robot 2020-09-15 9:19 ` kernel test robot 2020-09-15 9:19 ` kernel test robot 2020-09-15 11:57 ` kernel test robot 2020-09-15 11:57 ` kernel test robot 2020-09-15 11:57 ` kernel test robot 2020-09-14 13:30 ` Changing vma->vm_file in dma_buf_mmap() Christian König 2020-09-14 13:30 ` Christian König 2020-09-14 14:06 ` Jason Gunthorpe 2020-09-14 14:06 ` Jason Gunthorpe 2020-09-14 18:26 ` Christian König 2020-09-14 18:26 ` Christian König 2020-09-16 9:53 ` Daniel Vetter 2020-09-16 9:53 ` Daniel Vetter 2020-09-16 10:14 ` Christian König 2020-09-16 10:14 ` Christian König 2020-09-16 11:45 ` Christian König 2020-09-16 11:45 ` Christian König 2020-09-16 12:41 ` Daniel Vetter 2020-09-16 12:41 ` Daniel Vetter 2020-09-16 12:41 ` Daniel Vetter 2020-09-16 14:07 ` Jason Gunthorpe [this message] 2020-09-16 14:07 ` Jason Gunthorpe 2020-09-16 14:14 ` Christian König 2020-09-16 14:14 ` Christian König 2020-09-16 15:24 ` Daniel Vetter 2020-09-16 15:24 ` Daniel Vetter 2020-09-16 15:24 ` Daniel Vetter 2020-09-16 15:31 ` [Linaro-mm-sig] " Christian König 2020-09-16 15:31 ` Christian König 2020-09-16 15:31 ` Christian König 2020-09-17 6:23 ` Daniel Vetter 2020-09-17 6:23 ` Daniel Vetter 2020-09-17 6:23 ` Daniel Vetter 2020-09-17 7:11 ` Christian König 2020-09-17 7:11 ` Christian König 2020-09-17 7:11 ` Christian König 2020-09-17 8:09 ` Daniel Vetter 2020-09-17 8:09 ` Daniel Vetter 2020-09-17 8:09 ` Daniel Vetter 2020-09-17 11:31 ` Jason Gunthorpe 2020-09-17 11:31 ` Jason Gunthorpe 2020-09-17 12:03 ` Christian König 2020-09-17 12:03 ` Christian König 2020-09-17 12:18 ` Jason Gunthorpe 2020-09-17 12:18 ` Jason Gunthorpe 2020-09-17 12:18 ` Jason Gunthorpe 2020-09-17 12:24 ` Christian König 2020-09-17 12:24 ` Christian König 2020-09-17 12:24 ` Christian König 2020-09-17 12:26 ` Daniel Vetter 2020-09-17 12:26 ` Daniel Vetter 2020-09-17 12:26 ` Daniel Vetter 2020-09-17 14:35 ` Jason Gunthorpe 2020-09-17 14:35 ` Jason Gunthorpe 2020-09-17 14:35 ` Jason Gunthorpe 2020-09-17 14:54 ` Christian König 2020-09-17 14:54 ` Christian König 2020-09-17 14:54 ` Christian König 2020-09-17 15:24 ` Jason Gunthorpe 2020-09-17 15:24 ` Jason Gunthorpe 2020-09-17 15:24 ` Jason Gunthorpe 2020-09-17 15:37 ` Daniel Vetter 2020-09-17 15:37 ` Daniel Vetter 2020-09-17 16:06 ` Christian König 2020-09-17 16:06 ` Christian König 2020-09-17 16:06 ` Christian König 2020-09-17 16:39 ` Jason Gunthorpe 2020-09-17 16:39 ` Jason Gunthorpe 2020-09-17 16:39 ` Jason Gunthorpe 2020-09-17 17:23 ` Daniel Vetter 2020-09-17 17:23 ` Daniel Vetter
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