On Thu, May 28, 2020 at 4:34 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > On Thu, May 28, 2020 at 02:32:42AM +0530, Souptick Joarder wrote: > > This code was using get_user_pages_fast(), in a "Case 2" scenario > > (DMA/RDMA), using the categorization from [1]. That means that it's > > time to convert the get_user_pages_fast() + put_page() calls to > > pin_user_pages_fast() + unpin_user_page() calls. > > You are saying that the page is used for DIO and not DMA, but it sure > looks to me like it is used for DMA. No, I was referring to "Case 2" scenario in change log which means it is used for DMA, not DIO. > > 503 /* Map the page into DMA space. */ > 504 ptes[i].dma_addr = > 505 dma_map_page(pg_tbl->device, page, 0, PAGE_SIZE, > 506 DMA_BIDIRECTIONAL); > > To be honest, that starting paragraph was confusing. At first I thought > you were saying gasket was an RDMA driver. :P I shouldn't have to read > a different document to understand the commit message. It should be > summarized enough and the other documentation is supplemental. > > "In 2019 we introduced pin_user_pages() and now we are converting > get_user_pages() to the new API as appropriate". As all other similar conversion have similar change logs, so I was trying to maintain the same. John might have a different opinion on this. John, Any further opinion ?? > > > > > There is some helpful background in [2]: basically, this is a small > > part of fixing a long-standing disconnect between pinning pages, and > > file systems' use of those pages. > > What is the impact of this patch on runtime? I don't have the hardware to validate the runtime impact and will wait if someone is going to validate it for runtime impact. > > > > > [1] Documentation/core-api/pin_user_pages.rst > > > > [2] "Explicit pinning of user-space pages": > > https://lwn.net/Articles/807108/ > > > > Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx> > > Cc: John Hubbard <jhubbard@xxxxxxxxxx> > > > > Hi, > > > > I'm compile tested this, but unable to run-time test, so any testing > > help is much appriciated. > > --- > > The "Hi" part of patch should have been under the "---" cut off line so > this will definitely need to be resent. Sorry about it. Will wait for feedback from John before resend it :) > > regards, > dan carpenter > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
