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Subject[PATCH 20/26] ib: Convert ib_umem_get() to get_user_pages_unlocked()
Date
Convert ib_umem_get() to use get_user_pages_unlocked(). This
significantly shortens the section where mmap_sem is held (we only need
it for updating of mm->pinned_vm and inside get_user_pages()) and removes
the knowledge about locking of get_user_pages().

CC: Roland Dreier <roland@kernel.org>
CC: linux-rdma@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
drivers/infiniband/core/umem.c | 41 +++++++++++++++++------------------------
1 file changed, 17 insertions(+), 24 deletions(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index a84112322071..0640a89021a9 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -80,7 +80,6 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
{
struct ib_umem *umem;
struct page **page_list;
- struct vm_area_struct **vma_list;
struct ib_umem_chunk *chunk;
unsigned long locked;
unsigned long lock_limit;
@@ -125,34 +124,31 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
return ERR_PTR(-ENOMEM);
}

- /*
- * if we can't alloc the vma_list, it's not so bad;
- * just assume the memory is not hugetlb memory
- */
- vma_list = (struct vm_area_struct **) __get_free_page(GFP_KERNEL);
- if (!vma_list)
- umem->hugetlb = 0;
-
npages = PAGE_ALIGN(size + umem->offset) >> PAGE_SHIFT;

down_write(&current->mm->mmap_sem);

- locked = npages + current->mm->pinned_vm;
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-
- if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
- ret = -ENOMEM;
- goto out;
+ locked = npages;
+ if (npages + current->mm->pinned_vm > lock_limit &&
+ !capable(CAP_IPC_LOCK)) {
+ up_write(&current->mm->mmap_sem);
+ kfree(umem);
+ free_page((unsigned long) page_list);
+ return ERR_PTR(-ENOMEM);
}
+ current->mm->pinned_vm += npages;
+
+ up_write(&current->mm->mmap_sem);

cur_base = addr & PAGE_MASK;

ret = 0;
while (npages) {
- ret = get_user_pages(current, current->mm, cur_base,
+ ret = get_user_pages_unlocked(current, current->mm, cur_base,
min_t(unsigned long, npages,
PAGE_SIZE / sizeof (struct page *)),
- 1, !umem->writable, page_list, vma_list);
+ 1, !umem->writable, page_list);

if (ret < 0)
goto out;
@@ -174,8 +170,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
chunk->nents = min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK);
sg_init_table(chunk->page_list, chunk->nents);
for (i = 0; i < chunk->nents; ++i) {
- if (vma_list &&
- !is_vm_hugetlb_page(vma_list[i + off]))
+ if (!PageHuge(page_list[i + off]))
umem->hugetlb = 0;
sg_set_page(&chunk->page_list[i], page_list[i + off], PAGE_SIZE, 0);
}
@@ -206,12 +201,10 @@ out:
if (ret < 0) {
__ib_umem_release(context->device, umem, 0);
kfree(umem);
- } else
- current->mm->pinned_vm = locked;
-
- up_write(&current->mm->mmap_sem);
- if (vma_list)
- free_page((unsigned long) vma_list);
+ down_write(&current->mm->mmap_sem);
+ current->mm->pinned_vm -= locked;
+ up_write(&current->mm->mmap_sem);
+ }
free_page((unsigned long) page_list);

return ret < 0 ? ERR_PTR(ret) : umem;
--
1.8.1.4


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