From: John Hubbard <jhubbard@xxxxxxxxxx> Andrew, do you have a preference for which tree (MM or RDMA) this should go in? If not, then could you please ACK this so that Jason can pick it up for the RDMA tree? Changes since v3: -- Picks up Reviewed-by tags from Jan Kara and Dennis Dalessandro. -- Picks up Acked-by tag from Jason Gunthorpe, in case this ends up *not* going in via the RDMA tree. -- Fixes formatting of a comment. Changes since v2: -- Absorbed more dirty page handling logic into the put_user_page*(), and handled some page releasing loops in infiniband more thoroughly, as per Jason Gunthorpe's feedback. -- Fixed a bug in the put_user_pages*() routines' loops (thanks to Ralph Campbell for spotting it). Changes since v1: -- Renamed release_user_pages*() to put_user_pages*(), from Jan's feedback. -- Removed the goldfish.c changes, and instead, only included a single user (infiniband) of the new functions. That is because goldfish.c no longer has a name collision (it has a release_user_pages() routine), and also because infiniband exercises both the put_user_page() and put_user_pages*() paths. -- Updated links to discussions and plans, so as to be sure to include bounce buffers, thanks to Jerome's feedback. Also: -- Dennis, thanks for your earlier review, and I have not yet added your Reviewed-by tag, because this revision changes the things that you had previously reviewed, thus potentially requiring another look. This short series prepares for eventually fixing the problem described in [1], and is following a plan listed in [2], [3], [4]. Patch 1, although not technically critical to do now, is still nice to have, because it's already been reviewed by Jan, and it's just one more thing on the long TODO list here, that is ready to be checked off. Patch 2 is required in order to allow me (and others, if I'm lucky) to start submitting changes to convert all of the callsites of get_user_pages*() and put_page(). I think this will work a lot better than trying to maintain a massive patchset and submitting all at once. Patch 3 converts infiniband drivers: put_page() --> put_user_page(), and also exercises put_user_pages_dirty_locked(). Once these are all in, then the floodgates can open up to convert the large number of get_user_pages*() callsites. [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. [3]https://lkml.kernel.org/r/20180710082100.mkdwngdv5kkrcz6n@xxxxxxxxxxxxxx Bounce buffers (otherwise [2] is not really viable). [4] https://lkml.kernel.org/r/20181003162115.GG24030@xxxxxxxxxxxxxx Follow-up discussions. CC: Matthew Wilcox <willy@xxxxxxxxxxxxx> CC: Michal Hocko <mhocko@xxxxxxxxxx> CC: Christopher Lameter <cl@xxxxxxxxx> CC: Jason Gunthorpe <jgg@xxxxxxxx> CC: Dan Williams <dan.j.williams@xxxxxxxxx> CC: Jan Kara <jack@xxxxxxx> CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx> CC: Jerome Glisse <jglisse@xxxxxxxxxx> CC: Christoph Hellwig <hch@xxxxxxxxxxxxx> CC: Ralph Campbell <rcampbell@xxxxxxxxxx> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> John Hubbard (3): mm: get_user_pages: consolidate error handling mm: introduce put_user_page*(), placeholder versions infiniband/mm: convert put_page() to put_user_page*() drivers/infiniband/core/umem.c | 7 +-- drivers/infiniband/core/umem_odp.c | 2 +- drivers/infiniband/hw/hfi1/user_pages.c | 11 ++--- drivers/infiniband/hw/mthca/mthca_memfree.c | 6 +-- drivers/infiniband/hw/qib/qib_user_pages.c | 11 ++--- drivers/infiniband/hw/qib/qib_user_sdma.c | 8 ++-- drivers/infiniband/hw/usnic/usnic_uiom.c | 7 +-- include/linux/mm.h | 49 ++++++++++++++++++++- mm/gup.c | 37 +++++++++------- 9 files changed, 93 insertions(+), 45 deletions(-) -- 2.19.0
