[PATCH v2 3/3] mm: use vma_start_write_killable() in process_vma_walk_lock()

[Suren Baghdasaryan <surenb@google.com>]

Replace vma_start_write() with vma_start_write_killable() when
process_vma_walk_lock() is used with PGWALK_WRLOCK option.
Adjust its direct and indirect users to check for a possible error
and handle it.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 arch/s390/kvm/kvm-s390.c |  5 +++--
 arch/s390/mm/gmap.c      | 13 ++++++++++---
 fs/proc/task_mmu.c       |  7 ++++++-
 mm/pagewalk.c            | 20 ++++++++++++++------
 4 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 56a50524b3ee..75aef9c66e03 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -958,6 +958,7 @@ static int kvm_s390_get_mem_control(struct kvm *kvm, struct kvm_device_attr *att
 static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	int ret;
+	int err;
 	unsigned int idx;
 	switch (attr->attr) {
 	case KVM_S390_VM_MEM_ENABLE_CMMA:
@@ -990,10 +991,10 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
 		VM_EVENT(kvm, 3, "%s", "RESET: CMMA states");
 		mutex_lock(&kvm->lock);
 		idx = srcu_read_lock(&kvm->srcu);
-		s390_reset_cmma(kvm->arch.gmap->mm);
+		err = s390_reset_cmma(kvm->arch.gmap->mm);
 		srcu_read_unlock(&kvm->srcu, idx);
 		mutex_unlock(&kvm->lock);
-		ret = 0;
+		ret = (err < 0) ? err : 0;
 		break;
 	case KVM_S390_VM_MEM_LIMIT_SIZE: {
 		unsigned long new_limit;
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index dd85bcca817d..96054b124db5 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2271,6 +2271,7 @@ int s390_enable_skey(void)
 {
 	struct mm_struct *mm = current->mm;
 	int rc = 0;
+	int err;
 
 	mmap_write_lock(mm);
 	if (mm_uses_skeys(mm))
@@ -2282,7 +2283,9 @@ int s390_enable_skey(void)
 		mm->context.uses_skeys = 0;
 		goto out_up;
 	}
-	walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
+	err = walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
+	if (err < 0)
+		rc = err;
 
 out_up:
 	mmap_write_unlock(mm);
@@ -2305,11 +2308,15 @@ static const struct mm_walk_ops reset_cmma_walk_ops = {
 	.walk_lock		= PGWALK_WRLOCK,
 };
 
-void s390_reset_cmma(struct mm_struct *mm)
+int s390_reset_cmma(struct mm_struct *mm)
 {
+	int err;
+
 	mmap_write_lock(mm);
-	walk_page_range(mm, 0, TASK_SIZE, &reset_cmma_walk_ops, NULL);
+	err = walk_page_range(mm, 0, TASK_SIZE, &reset_cmma_walk_ops, NULL);
 	mmap_write_unlock(mm);
+
+	return (err < 0) ? err : 0;
 }
 EXPORT_SYMBOL_GPL(s390_reset_cmma);
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index d7d52e259055..91e806d65bd9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1797,6 +1797,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 		struct clear_refs_private cp = {
 			.type = type,
 		};
+		int err;
 
 		if (mmap_write_lock_killable(mm)) {
 			count = -EINTR;
@@ -1824,7 +1825,11 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 						0, mm, 0, -1UL);
 			mmu_notifier_invalidate_range_start(&range);
 		}
-		walk_page_range(mm, 0, -1, &clear_refs_walk_ops, &cp);
+		err = walk_page_range(mm, 0, -1, &clear_refs_walk_ops, &cp);
+		if (err < 0) {
+			count = err;
+			goto out_unlock;
+		}
 		if (type == CLEAR_REFS_SOFT_DIRTY) {
 			mmu_notifier_invalidate_range_end(&range);
 			flush_tlb_mm(mm);
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index a94c401ab2cf..dc9f7a7709c6 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -425,14 +425,13 @@ static inline void process_mm_walk_lock(struct mm_struct *mm,
 		mmap_assert_write_locked(mm);
 }
 
-static inline void process_vma_walk_lock(struct vm_area_struct *vma,
+static inline int process_vma_walk_lock(struct vm_area_struct *vma,
 					 enum page_walk_lock walk_lock)
 {
 #ifdef CONFIG_PER_VMA_LOCK
 	switch (walk_lock) {
 	case PGWALK_WRLOCK:
-		vma_start_write(vma);
-		break;
+		return vma_start_write_killable(vma);
 	case PGWALK_WRLOCK_VERIFY:
 		vma_assert_write_locked(vma);
 		break;
@@ -444,6 +443,7 @@ static inline void process_vma_walk_lock(struct vm_area_struct *vma,
 		break;
 	}
 #endif
+	return 0;
 }
 
 /*
@@ -487,7 +487,9 @@ int walk_page_range_mm_unsafe(struct mm_struct *mm, unsigned long start,
 			if (ops->pte_hole)
 				err = ops->pte_hole(start, next, -1, &walk);
 		} else { /* inside vma */
-			process_vma_walk_lock(vma, ops->walk_lock);
+			err = process_vma_walk_lock(vma, ops->walk_lock);
+			if (err)
+				break;
 			walk.vma = vma;
 			next = min(end, vma->vm_end);
 			vma = find_vma(mm, vma->vm_end);
@@ -704,6 +706,7 @@ int walk_page_range_vma_unsafe(struct vm_area_struct *vma, unsigned long start,
 		.vma		= vma,
 		.private	= private,
 	};
+	int err;
 
 	if (start >= end || !walk.mm)
 		return -EINVAL;
@@ -711,7 +714,9 @@ int walk_page_range_vma_unsafe(struct vm_area_struct *vma, unsigned long start,
 		return -EINVAL;
 
 	process_mm_walk_lock(walk.mm, ops->walk_lock);
-	process_vma_walk_lock(vma, ops->walk_lock);
+	err = process_vma_walk_lock(vma, ops->walk_lock);
+	if (err)
+		return err;
 	return __walk_page_range(start, end, &walk);
 }
 
@@ -734,6 +739,7 @@ int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 		.vma		= vma,
 		.private	= private,
 	};
+	int err;
 
 	if (!walk.mm)
 		return -EINVAL;
@@ -741,7 +747,9 @@ int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 		return -EINVAL;
 
 	process_mm_walk_lock(walk.mm, ops->walk_lock);
-	process_vma_walk_lock(vma, ops->walk_lock);
+	err = process_vma_walk_lock(vma, ops->walk_lock);
+	if (err)
+		return err;
 	return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
 }
 
-- 
2.53.0.273.g2a3d683680-goog