Commit b95df5e3 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Jason Gunthorpe
Browse files

drivers/IB,core: reduce scope of mmap_sem 



ib_umem_get() uses gup_longterm() and relies on the lock to stabilze the
vma_list, so we cannot really get rid of mmap_sem altogether, but now that
the counter is atomic, we can get of some complexity that mmap_sem brings
with only pinned_vm.

Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent 8ea1f989

drivers/infiniband/core/umem.c

+2 −39
Original line number Diff line number Diff line
@@ -165,15 +165,12 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr, 


	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;



	down_write(&mm->mmap_sem);

	new_pinned = atomic64_read(&mm->pinned_vm) + npages;

	new_pinned = atomic64_add_return(npages, &mm->pinned_vm);

	if (new_pinned > lock_limit && !capable(CAP_IPC_LOCK)) {

		up_write(&mm->mmap_sem);

		atomic64_sub(npages, &mm->pinned_vm);

		ret = -ENOMEM;

		goto out;

	}

	atomic64_set(&mm->pinned_vm, new_pinned);

	up_write(&mm->mmap_sem);



	cur_base = addr & PAGE_MASK;
@@ -233,9 +230,7 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr, 
umem_release:

	__ib_umem_release(context->device, umem, 0);

vma:

	down_write(&mm->mmap_sem);

	atomic64_sub(ib_umem_num_pages(umem), &mm->pinned_vm);

	up_write(&mm->mmap_sem);

out:

	if (vma_list)

		free_page((unsigned long) vma_list);
@@ -258,25 +253,12 @@ static void __ib_umem_release_tail(struct ib_umem *umem) 
		kfree(umem);

}



static void ib_umem_release_defer(struct work_struct *work)

{

	struct ib_umem *umem = container_of(work, struct ib_umem, work);



	down_write(&umem->owning_mm->mmap_sem);

	atomic64_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm);

	up_write(&umem->owning_mm->mmap_sem);



	__ib_umem_release_tail(umem);

}



/**

 * ib_umem_release - release memory pinned with ib_umem_get

 * @umem: umem struct to release

 */

void ib_umem_release(struct ib_umem *umem)

{

	struct ib_ucontext *context = umem->context;



	if (umem->is_odp) {

		ib_umem_odp_release(to_ib_umem_odp(umem));

		__ib_umem_release_tail(umem);
@@ -285,26 +267,7 @@ void ib_umem_release(struct ib_umem *umem) 


	__ib_umem_release(umem->context->device, umem, 1);



	/*

	 * We may be called with the mm's mmap_sem already held.  This

	 * can happen when a userspace munmap() is the call that drops

	 * the last reference to our file and calls our release

	 * method.  If there are memory regions to destroy, we'll end

	 * up here and not be able to take the mmap_sem.  In that case

	 * we defer the vm_locked accounting a workqueue.

	 */

	if (context->closing) {

		if (!down_write_trylock(&umem->owning_mm->mmap_sem)) {

			INIT_WORK(&umem->work, ib_umem_release_defer);

			queue_work(ib_wq, &umem->work);

			return;

		}

	} else {

		down_write(&umem->owning_mm->mmap_sem);

	}

	atomic64_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm);

	up_write(&umem->owning_mm->mmap_sem);



	__ib_umem_release_tail(umem);

}

EXPORT_SYMBOL(ib_umem_release);

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