On Mon, May 06, 2019 at 04:29:38PM -0700, rcampbell@xxxxxxxxxx wrote: > From: Ralph Campbell <rcampbell@xxxxxxxxxx> > > Update the HMM documentation to reflect the latest API and make a few minor > wording changes. > > Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> > Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx> > Cc: John Hubbard <jhubbard@xxxxxxxxxx> > Cc: Ira Weiny <ira.weiny@xxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxx> > Cc: Balbir Singh <bsingharora@xxxxxxxxx> > Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Documentation/vm/hmm.rst | 139 ++++++++++++++++++++------------------- > 1 file changed, 73 insertions(+), 66 deletions(-) Okay, lets start picking up hmm patches in to the new shared hmm.git, as promised I will take responsibility to send these to Linus. The tree is here: https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/log/?h=hmm This looks fine to me with one minor comment: > diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst > index ec1efa32af3c..7c1e929931a0 100644 > +++ b/Documentation/vm/hmm.rst > > @@ -151,21 +151,27 @@ registration of an hmm_mirror struct:: > > int hmm_mirror_register(struct hmm_mirror *mirror, > struct mm_struct *mm); > - int hmm_mirror_register_locked(struct hmm_mirror *mirror, > - struct mm_struct *mm); > > - > -The locked variant is to be used when the driver is already holding mmap_sem > -of the mm in write mode. The mirror struct has a set of callbacks that are used > +The mirror struct has a set of callbacks that are used > to propagate CPU page tables:: > > struct hmm_mirror_ops { > + /* release() - release hmm_mirror > + * > + * @mirror: pointer to struct hmm_mirror > + * > + * This is called when the mm_struct is being released. > + * The callback should make sure no references to the mirror occur > + * after the callback returns. > + */ This is not quite accurate (at least, as the other series I sent intends), the struct hmm_mirror is valid up until hmm_mirror_unregister() is called - specifically it remains valid after the release() callback. I will revise it (and the hmm.h comment it came from) to read the below. Please let me know if you'd like something else: /* release() - release hmm_mirror * * @mirror: pointer to struct hmm_mirror * * This is called when the mm_struct is being released. The callback * must ensure that all access to any pages obtained from this mirror * is halted before the callback returns. All future access should * fault. */ The key task for release is to fence off all device access to any related pages as the mm is about to recycle them and the device must not cause a use-after-free. I applied it to hmm.git Thanks, Jason
