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RDMA: Convert put_page() to put_user_page*()

Bladeren bron 
For infiniband code that retains pages via get_user_pages*(), release
those pages via the new put_user_page(), or put_user_pages*(), instead of
put_page()

This is a tiny part of the second step of fixing the problem described in
[1]. The steps are:

1) Provide put_user_page*() routines, intended to be used for releasing
   pages that were pinned via get_user_pages*().

2) Convert all of the call sites for get_user_pages*(), to invoke
   put_user_page*(), instead of put_page(). This involves dozens of call
   sites, and will take some time.

3) After (2) is complete, use get_user_pages*() and put_user_page*() to
   implement tracking of these pages. This tracking will be separate from
   the existing struct page refcounting.

4) Use the tracking and identification of these pages, to implement
   special handling (especially in writeback paths) when the pages are
   backed by a filesystem. Again, [1] provides details as to why that is
   desirable.

[1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()"

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Jason Gunthorpe <jgg@mellanox.com>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
John Hubbard
2019-05-24 18:45:22 -07:00
gecommit door Jason Gunthorpe
bovenliggende cfcc048ca7
commit ea99697458
7 gewijzigde bestanden met toevoegingen van 27 en 31 verwijderingen
Download Patch-bestand Download Diff-bestand Expand all files Collapse all files

11
drivers/infiniband/hw/qib/qib_user_pages.c
Bestand weergeven

@@ -40,13 +40,10 @@
static void __qib_release_user_pages(struct page **p, size_t num_pages,
int dirty)
{
size_t i;
for (i = 0; i < num_pages; i++) {
if (dirty)
set_page_dirty_lock(p[i]);
put_page(p[i]);
}
if (dirty)
put_user_pages_dirty_lock(p, num_pages);
else
put_user_pages(p, num_pages);
}
/**

6
drivers/infiniband/hw/qib/qib_user_sdma.c
Bestand weergeven

@@ -317,7 +317,7 @@ static int qib_user_sdma_page_to_frags(const struct qib_devdata *dd,
* the caller can ignore this page.
*/
if (put) {
put_page(page);
put_user_page(page);
} else {
/* coalesce case */
kunmap(page);
@@ -631,7 +631,7 @@ static void qib_user_sdma_free_pkt_frag(struct device *dev,
kunmap(pkt->addr[i].page);
if (pkt->addr[i].put_page)
put_page(pkt->addr[i].page);
put_user_page(pkt->addr[i].page);
else
__free_page(pkt->addr[i].page);
} else if (pkt->addr[i].kvaddr) {
@@ -706,7 +706,7 @@ static int qib_user_sdma_pin_pages(const struct qib_devdata *dd,
/* if error, return all pages not managed by pkt */
free_pages:
while (i < j)
put_page(pages[i++]);
put_user_page(pages[i++]);
done:
return ret;