On Mon, Nov 02, 2020 at 02:08:36PM +0000, Matthew Wilcox wrote: > On Mon, Nov 02, 2020 at 02:33:43PM +0100, Greg Kroah-Hartman wrote: > > > Oh, ugh, sysfs_emit() should be able to work on a buffer that isn't > > > page aligned. Greg, how about this? > > > > How can sysfs_emit() be called on a non-page-aligned buffer? It's being > > used on the buffer that was passed to the sysfs call. > > > > And if you are writing multiple values to a single sysfs file output, > > well, not good... > > See shmem_enabled_show() in mm/shmem.c (output at > /sys/kernel/mm/transparent_hugepage/shmem_enabled on your machine). > > I don't claim it's a good interface, but it exists. Ok, that's a common pattern for sysfs files, not that bad. What's wrong with using sysfs_emit_at()? We want sysfs_emit() to "know" that the buffer is PAGE_SIZE big, if you try to allow offsets in it, that defeats the purpose of the check. Or am I missing something else here? thanks, greg k-h
