On Wed, Jun 05, 2024 at 01:29:29PM -0600, Martin Oliveira wrote: > The standard kernfs vm_ops installs a page_mkwrite() operator which > modifies the file update time on write. > > This not always required (or makes sense), such as in the P2PDMA, which > uses the sysfs file as an allocator from userspace. That's not a good idea, please don't do that. sysfs binary files are "pass through", why would you want to use this as an allocator? > Furthermore, having the page_mkwrite() operator causes > writable_file_mapping_allowed() to fail due to > vma_needs_dirty_tracking() on the gup flow, which is a pre-requisite for > enabling P2PDMA over RDMA. > > Fix this by adding a new boolean on kernfs_ops to differentiate between > the different behaviours. This isn't going to work well. What exactly are you wanting to do in sysfs that you feel this is required? thanks, greg k-h
