[PATCH 0/2] Two HMM patches from MMOTS

[PATCH 0/2] Two HMM patches from MMOTS

[Kuehling, Felix]

These are two important HMM bug fixes to fix the HMM-based userptr
implementation. They are alread staged in MMOTS:
https://www.ozlabs.org/~akpm/mmots/broken-out/

Kuehling, Felix (1):
  mm/hmm.c: only set FAULT_FLAG_ALLOW_RETRY for non-blocking

Philip Yang (1):
  mm/hmm.c: support automatic NUMA balancing

 mm/hmm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.17.1

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[PATCH 1/2] mm/hmm.c: support automatic NUMA balancing

[Kuehling, Felix]

From: Philip Yang <Philip.Yang@amd.com>

While the page is migrating by NUMA balancing, HMM failed to detect this
condition and still return the old page.  Application will use the new
page migrated, but driver pass the old page physical address to GPU, this
crash the application later.

Use pte_protnone(pte) to return this condition and then hmm_vma_do_fault
will allocate new page.

Link: http://lkml.kernel.org/r/20190510195258.9930-2-Felix.Kuehling@amd.com
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Alex Deucher <alex.deucher@amd.com>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/hmm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index 0db8491090b8..599d8e82db67 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -559,7 +559,7 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk,
 
 static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
 {
-	if (pte_none(pte) || !pte_present(pte))
+	if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
 		return 0;
 	return pte_write(pte) ? range->flags[HMM_PFN_VALID] |
 				range->flags[HMM_PFN_WRITE] :
-- 
2.17.1

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[PATCH 2/2] mm/hmm.c: only set FAULT_FLAG_ALLOW_RETRY for non-blocking

[Kuehling, Felix]

From: "Kuehling, Felix" <Felix.Kuehling@amd.com>

Don't set this flag by default in hmm_vma_do_fault. It is set
conditionally just a few lines below. Setting it unconditionally
can lead to handle_mm_fault doing a non-blocking fault, returning
-EBUSY and unlocking mmap_sem unexpectedly.

Link: http://lkml.kernel.org/r/20190510195258.9930-3-Felix.Kuehling@amd.com
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Alex Deucher <alex.deucher@amd.com>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/hmm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index 599d8e82db67..018cb5c241a6 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -339,7 +339,7 @@ struct hmm_vma_walk {
 static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
 			    bool write_fault, uint64_t *pfn)
 {
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_REMOTE;
+	unsigned int flags = FAULT_FLAG_REMOTE;
 	struct hmm_vma_walk *hmm_vma_walk = walk->private;
 	struct hmm_range *range = hmm_vma_walk->range;
 	struct vm_area_struct *vma = walk->vma;
-- 
2.17.1

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