On Thu, Sep 27, 2018 at 10:39:47PM -0700, john.hubbard@xxxxxxxxx wrote: > From: John Hubbard <jhubbard@xxxxxxxxxx> > > For code that retains pages via get_user_pages*(), > release those pages via the new put_user_page(), > instead of put_page(). > > This prepares for eventually fixing the problem described > in [1], and is following a plan listed in [2]. > > [1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()" > > [2] https://lkml.kernel.org/r/20180709080554.21931-1-jhubbard@xxxxxxxxxx > Proposed steps for fixing get_user_pages() + DMA problems. > > CC: Doug Ledford <dledford@xxxxxxxxxx> > CC: Jason Gunthorpe <jgg@xxxxxxxx> > CC: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx> > CC: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx> > CC: Christian Benvenuti <benve@xxxxxxxxx> > > CC: linux-rdma@xxxxxxxxxxxxxxx > CC: linux-kernel@xxxxxxxxxxxxxxx > CC: linux-mm@xxxxxxxxx > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> > drivers/infiniband/core/umem.c | 2 +- > drivers/infiniband/core/umem_odp.c | 2 +- > drivers/infiniband/hw/hfi1/user_pages.c | 2 +- > drivers/infiniband/hw/mthca/mthca_memfree.c | 6 +++--- > drivers/infiniband/hw/qib/qib_user_pages.c | 2 +- > drivers/infiniband/hw/qib/qib_user_sdma.c | 8 ++++---- > drivers/infiniband/hw/usnic/usnic_uiom.c | 2 +- > 7 files changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c > index a41792dbae1f..9430d697cb9f 100644 > +++ b/drivers/infiniband/core/umem.c > @@ -60,7 +60,7 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d > page = sg_page(sg); > if (!PageDirty(page) && umem->writable && dirty) > set_page_dirty_lock(page); > - put_page(page); > + put_user_page(page); Would it make sense to have a release/put_user_pages_dirtied to absorb the set_page_dity pattern too? I notice in this patch there is some variety here, I wonder what is the right way? Also, I'm told this code here is a big performance bottleneck when the number of pages becomes very long (think >> GB of memory), so having a future path to use some kind of batching/threading sound great. Otherwise this RDMA part seems fine to me, there might be some minor conflicts however. I assume you want to run this through the -mm tree? Acked-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Jason
