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Subject[PATCH] staging: gasket: Convert get_user_pages*() --> pin_user_pages*()
Date
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.

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.

[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@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>

Hi,

I'm compile tested this, but unable to run-time test, so any testing
help is much appriciated.
---
drivers/staging/gasket/gasket_page_table.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
index f6d7157..d712ad4 100644
--- a/drivers/staging/gasket/gasket_page_table.c
+++ b/drivers/staging/gasket/gasket_page_table.c
@@ -449,7 +449,7 @@ static bool gasket_release_page(struct page *page)

if (!PageReserved(page))
SetPageDirty(page);
- put_page(page);
+ unpin_user_page(page);

return true;
}
@@ -486,12 +486,12 @@ static int gasket_perform_mapping(struct gasket_page_table *pg_tbl,
ptes[i].dma_addr = pg_tbl->coherent_pages[0].paddr +
off + i * PAGE_SIZE;
} else {
- ret = get_user_pages_fast(page_addr - offset, 1,
+ ret = pin_user_pages_fast(page_addr - offset, 1,
FOLL_WRITE, &page);

if (ret <= 0) {
dev_err(pg_tbl->device,
- "get user pages failed for addr=0x%lx, offset=0x%lx [ret=%d]\n",
+ "pin user pages failed for addr=0x%lx, offset=0x%lx [ret=%d]\n",
page_addr, offset, ret);
return ret ? ret : -ENOMEM;
}
--
1.9.1
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