Commit 515f12b9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma 

Pull HMM fixes from Jason Gunthorpe:
 "Fix the locking around nouveau's use of the hmm_range_* APIs. It works
  correctly in the success case, but many of the the edge cases have
  missing unlocks or double unlocks.

  The diffstat is a bit big as Christoph did a comprehensive job to move
  the obsolete API from the core header and into the driver before
  fixing its flow, but the risk of regression from this code motion is
  low"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  nouveau: unlock mmap_sem on all errors from nouveau_range_fault
  nouveau: remove the block parameter to nouveau_range_fault
  mm/hmm: move hmm_vma_range_done and hmm_vma_fault to nouveau
  mm/hmm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot}
parents 2a11c76e de4ee728

Documentation/vm/hmm.rst

+1 −1
Original line number Diff line number Diff line
@@ -237,7 +237,7 @@ The usage pattern is:: 
      ret = hmm_range_snapshot(&range);

      if (ret) {

          up_read(&mm->mmap_sem);

          if (ret == -EAGAIN) {

          if (ret == -EBUSY) {

            /*

             * No need to check hmm_range_wait_until_valid() return value

             * on retry we will get proper error with hmm_range_snapshot()

drivers/gpu/drm/nouveau/nouveau_svm.c

+44 −3
Original line number Diff line number Diff line
@@ -475,6 +475,47 @@ nouveau_svm_fault_cache(struct nouveau_svm *svm, 
		fault->inst, fault->addr, fault->access);

}



static inline bool

nouveau_range_done(struct hmm_range *range)

{

	bool ret = hmm_range_valid(range);



	hmm_range_unregister(range);

	return ret;

}



static int

nouveau_range_fault(struct hmm_mirror *mirror, struct hmm_range *range)

{

	long ret;



	range->default_flags = 0;

	range->pfn_flags_mask = -1UL;



	ret = hmm_range_register(range, mirror,

				 range->start, range->end,

				 PAGE_SHIFT);

	if (ret) {

		up_read(&range->vma->vm_mm->mmap_sem);

		return (int)ret;

	}



	if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {

		up_read(&range->vma->vm_mm->mmap_sem);

		return -EAGAIN;

	}



	ret = hmm_range_fault(range, true);

	if (ret <= 0) {

		if (ret == 0)

			ret = -EBUSY;

		up_read(&range->vma->vm_mm->mmap_sem);

		hmm_range_unregister(range);

		return ret;

	}

	return 0;

}



static int

nouveau_svm_fault(struct nvif_notify *notify)

{
@@ -649,10 +690,10 @@ nouveau_svm_fault(struct nvif_notify *notify) 
		range.values = nouveau_svm_pfn_values;

		range.pfn_shift = NVIF_VMM_PFNMAP_V0_ADDR_SHIFT;

again:

		ret = hmm_vma_fault(&svmm->mirror, &range, true);

		ret = nouveau_range_fault(&svmm->mirror, &range);

		if (ret == 0) {

			mutex_lock(&svmm->mutex);

			if (!hmm_vma_range_done(&range)) {

			if (!nouveau_range_done(&range)) {

				mutex_unlock(&svmm->mutex);

				goto again;

			}
@@ -666,8 +707,8 @@ nouveau_svm_fault(struct nvif_notify *notify) 
						NULL);

			svmm->vmm->vmm.object.client->super = false;

			mutex_unlock(&svmm->mutex);

		}

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

		}



		/* Cancel any faults in the window whose pages didn't manage

		 * to keep their valid bit, or stay writeable when required.

include/linux/hmm.h

+0 −54
Original line number Diff line number Diff line
@@ -484,60 +484,6 @@ long hmm_range_dma_unmap(struct hmm_range *range, 
 */

#define HMM_RANGE_DEFAULT_TIMEOUT 1000



/* This is a temporary helper to avoid merge conflict between trees. */

static inline bool hmm_vma_range_done(struct hmm_range *range)

{

	bool ret = hmm_range_valid(range);



	hmm_range_unregister(range);

	return ret;

}



/* This is a temporary helper to avoid merge conflict between trees. */

static inline int hmm_vma_fault(struct hmm_mirror *mirror,

				struct hmm_range *range, bool block)

{

	long ret;



	/*

	 * With the old API the driver must set each individual entries with

	 * the requested flags (valid, write, ...). So here we set the mask to

	 * keep intact the entries provided by the driver and zero out the

	 * default_flags.

	 */

	range->default_flags = 0;

	range->pfn_flags_mask = -1UL;



	ret = hmm_range_register(range, mirror,

				 range->start, range->end,

				 PAGE_SHIFT);

	if (ret)

		return (int)ret;



	if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {

		/*

		 * The mmap_sem was taken by driver we release it here and

		 * returns -EAGAIN which correspond to mmap_sem have been

		 * drop in the old API.

		 */

		up_read(&range->vma->vm_mm->mmap_sem);

		return -EAGAIN;

	}



	ret = hmm_range_fault(range, block);

	if (ret <= 0) {

		if (ret == -EBUSY || !ret) {

			/* Same as above, drop mmap_sem to match old API. */

			up_read(&range->vma->vm_mm->mmap_sem);

			ret = -EBUSY;

		} else if (ret == -EAGAIN)

			ret = -EBUSY;

		hmm_range_unregister(range);

		return ret;

	}

	return 0;

}



/* Below are for HMM internal use only! Not to be used by device driver! */

static inline void hmm_mm_init(struct mm_struct *mm)

{

mm/hmm.c

+4 −6
Original line number Diff line number Diff line
@@ -946,7 +946,7 @@ EXPORT_SYMBOL(hmm_range_unregister); 
 * @range: range

 * Return: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid

 *          permission (for instance asking for write and range is read only),

 *          -EAGAIN if you need to retry, -EFAULT invalid (ie either no valid

 *          -EBUSY if you need to retry, -EFAULT invalid (ie either no valid

 *          vma or it is illegal to access that range), number of valid pages

 *          in range->pfns[] (from range start address).

 *
@@ -967,7 +967,7 @@ long hmm_range_snapshot(struct hmm_range *range) 
	do {

		/* If range is no longer valid force retry. */

		if (!range->valid)

			return -EAGAIN;

			return -EBUSY;



		vma = find_vma(hmm->mm, start);

		if (vma == NULL || (vma->vm_flags & device_vma))
@@ -1062,10 +1062,8 @@ long hmm_range_fault(struct hmm_range *range, bool block) 


	do {

		/* If range is no longer valid force retry. */

		if (!range->valid) {

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

			return -EAGAIN;

		}

		if (!range->valid)

			return -EBUSY;



		vma = find_vma(hmm->mm, start);

		if (vma == NULL || (vma->vm_flags & device_vma))