On Mon, Feb 12, 2018 at 03:32:36PM -0800, Kees Cook wrote: > On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <igor.sto...@huawei.com> wrote: > > This patch-set introduces the possibility of protecting memory that has > > been allocated dynamically. > > > > The memory is managed in pools: when a memory pool is turned into R/O, > > all the memory that is part of it, will become R/O. > > > > A R/O pool can be destroyed, to recover its memory, but it cannot be > > turned back into R/W mode. > > > > This is intentional. This feature is meant for data that doesn't need > > further modifications after initialization. > > This series came up in discussions with Dave Chinner (and Matthew > Wilcox, already part of the discussion, and others) at LCA. I wonder > if XFS would make a good initial user of this, as it could allocate > all the function pointers and other const information about a > superblock in pmalloc(), keeping it separate from the R/W portions? > Could other filesystems do similar things?
I wasn't cc'd on this patchset, (please use da...@fromorbit.com for future postings) so I can't really say anything about it right now. My interest for XFS was that we have a fair amount of static data in XFS that we set up at mount time and it never gets modified after that. I'm not so worried about VFS level objects (that's a much more complex issue) but there is a lot of low hanging fruit in the XFS structures we could convert to write-once structures. Cheers, Dave. -- Dave Chinner dchin...@redhat.com