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Commit 40ddacf2 authored by Leon Romanovsky's avatar Leon Romanovsky Committed by Jason Gunthorpe
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RDMA/umem: Don't hold mmap_sem for too long 



DMA mapping is time consuming operation and doesn't need to be performed
with mmap_sem semaphore is held.

The semaphore only needs to be held for accounting and get_user_pages
related activities.

Signed-off-by: default avatarHuy Nguyen <huyn@mellanox.com>
Signed-off-by: default avatarLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent 6869e000

drivers/infiniband/core/umem.c

+14 −10
Original line number Diff line number Diff line
@@ -84,7 +84,6 @@ 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;

	unsigned long locked;

	unsigned long lock_limit;

	unsigned long cur_base;

	unsigned long npages;
@@ -149,15 +148,16 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, 


	npages = ib_umem_num_pages(umem);



	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)) {

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

	current->mm->pinned_vm += npages;

	if ((current->mm->pinned_vm > lock_limit) && !capable(CAP_IPC_LOCK)) {

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

		ret = -ENOMEM;

		goto out;

	}

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



	cur_base = addr & PAGE_MASK;
@@ -176,14 +176,16 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, 
	need_release = 1;

	sg_list_start = umem->sg_head.sgl;



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

	while (npages) {

		ret = get_user_pages_longterm(cur_base,

				     min_t(unsigned long, npages,

					   PAGE_SIZE / sizeof (struct page *)),

				     gup_flags, page_list, vma_list);



		if (ret < 0)

		if (ret < 0) {

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

			goto out;

		}



		umem->npages += ret;

		cur_base += ret * PAGE_SIZE;
@@ -199,6 +201,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, 
		/* preparing for next loop */

		sg_list_start = sg;

	}

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



	umem->nmap = ib_dma_map_sg_attrs(context->device,

				  umem->sg_head.sgl,
@@ -215,13 +218,14 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, 


out:

	if (ret < 0) {

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

		current->mm->pinned_vm -= ib_umem_num_pages(umem);

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

		if (need_release)

			__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);

	free_page((unsigned long) page_list);