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IB/mthca: Fix gup usage in mthca_map_user_db()

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get_user_pages() must be called with mmap_sem held, currently
it is not. In fact it is called under the user db_table->mutex.
To fix this we can convert gup to use the fast alternative,
and safely avoid taking mmap_sem, if possible. Furthermore
this is safe wrt to the mutex as other callers that take the
lock (unmap and alloc_db) are not called under mmap_sem
(hence possible deadlock).

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Davidlohr Bueso 2018-01-25 11:27:27 -08:00 committed by Doug Ledford
parent dc728f779a
commit 487f6683f1
1 changed files with 1 additions and 1 deletions
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2
drivers/infiniband/hw/mthca/mthca_memfree.c
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@ -472,7 +472,7 @@ int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
goto out;
}
ret = get_user_pages(uaddr & PAGE_MASK, 1, FOLL_WRITE, pages, NULL);
ret = get_user_pages_fast(uaddr & PAGE_MASK, 1, FOLL_WRITE, pages);
if (ret < 0)
goto out;