On 11.08.22 12:21, Greg KH wrote: > On Thu, Aug 11, 2022 at 11:46:09AM +0200, Alexander Grund wrote: >> I mean this patch removes a superflous pointer of the superblock struct >> making the kernel use less memory. > > Also, how much measurable memory does this save? You did not quantify > it. It saves one pointer, i.e. usually 8 Byte, per superblock when using SELinux. I don't know how many of those superblocks will be allocated in total on usual systems as I'm not familiar with the details of the filesystems. However following one callchain leads to > /* > * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that > * will never be mountable) > */ > struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, So it seems one superblock even for each pseudo-fs of which there can be many. A quick experiment [1] on my phone shows about 300 superblocks allocated which means that the patch saves a bit over 2kB of memory. So not that much on usual systems but could be much for some embedded systems. I hope that helps, Alex [1] For the experiment I added a debug counter to `superblock_alloc_security`
