[PATCH v3 3/3] mm: use vma_start_write_killable() in process_vma_walk_lock()
Suren Baghdasaryan
surenb at google.com
Thu Feb 26 18:06:09 AEDT 2026
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. Ensure users handle EINTR correctly and do not ignore
it.
Signed-off-by: Suren Baghdasaryan <surenb at google.com>
---
arch/s390/kvm/kvm-s390.c | 2 +-
fs/proc/task_mmu.c | 5 ++++-
mm/mempolicy.c | 14 +++++++++++---
mm/pagewalk.c | 20 ++++++++++++++------
mm/vma.c | 22 ++++++++++++++--------
mm/vma.h | 6 ++++++
6 files changed, 50 insertions(+), 19 deletions(-)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 7a175d86cef0..337e4f7db63a 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2948,7 +2948,7 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
}
/* must be called without kvm->lock */
r = kvm_s390_handle_pv(kvm, &args);
- if (copy_to_user(argp, &args, sizeof(args))) {
+ if (r != -EINTR && copy_to_user(argp, &args, sizeof(args))) {
r = -EFAULT;
break;
}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e091931d7ca1..1238a2988eb6 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 +1825,9 @@ 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;
if (type == CLEAR_REFS_SOFT_DIRTY) {
mmu_notifier_invalidate_range_end(&range);
flush_tlb_mm(mm);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 90939f5bde02..3c8b3dfc9c56 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -988,6 +988,8 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
&queue_pages_lock_vma_walk_ops : &queue_pages_walk_ops;
err = walk_page_range(mm, start, end, ops, &qp);
+ if (err == -EINTR)
+ return err;
if (!qp.first)
/* whole range in hole */
@@ -1309,9 +1311,14 @@ static long migrate_to_node(struct mm_struct *mm, int source, int dest,
flags | MPOL_MF_DISCONTIG_OK, &pagelist);
mmap_read_unlock(mm);
+ if (nr_failed == -EINTR)
+ err = nr_failed;
+
if (!list_empty(&pagelist)) {
- err = migrate_pages(&pagelist, alloc_migration_target, NULL,
- (unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL);
+ if (!err)
+ err = migrate_pages(&pagelist, alloc_migration_target,
+ NULL, (unsigned long)&mtc,
+ MIGRATE_SYNC, MR_SYSCALL, NULL);
if (err)
putback_movable_pages(&pagelist);
}
@@ -1611,7 +1618,8 @@ static long do_mbind(unsigned long start, unsigned long len,
MR_MEMPOLICY_MBIND, NULL);
}
- if (nr_failed && (flags & MPOL_MF_STRICT))
+ /* Do not mask EINTR */
+ if ((err != -EINTR) && (nr_failed && (flags & MPOL_MF_STRICT)))
err = -EIO;
if (!list_empty(&pagelist))
putback_movable_pages(&pagelist);
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);
}
diff --git a/mm/vma.c b/mm/vma.c
index 9f2664f1d078..46bbad6e64a4 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -998,14 +998,18 @@ static __must_check struct vm_area_struct *vma_merge_existing_range(
if (anon_dup)
unlink_anon_vmas(anon_dup);
- /*
- * This means we have failed to clone anon_vma's correctly, but no
- * actual changes to VMAs have occurred, so no harm no foul - if the
- * user doesn't want this reported and instead just wants to give up on
- * the merge, allow it.
- */
- if (!vmg->give_up_on_oom)
- vmg->state = VMA_MERGE_ERROR_NOMEM;
+ if (err == -EINTR) {
+ vmg->state = VMA_MERGE_ERROR_INTR;
+ } else {
+ /*
+ * This means we have failed to clone anon_vma's correctly,
+ * but no actual changes to VMAs have occurred, so no harm no
+ * foul - if the user doesn't want this reported and instead
+ * just wants to give up on the merge, allow it.
+ */
+ if (!vmg->give_up_on_oom)
+ vmg->state = VMA_MERGE_ERROR_NOMEM;
+ }
return NULL;
}
@@ -1681,6 +1685,8 @@ static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg)
merged = vma_merge_existing_range(vmg);
if (merged)
return merged;
+ if (vmg_intr(vmg))
+ return ERR_PTR(-EINTR);
if (vmg_nomem(vmg))
return ERR_PTR(-ENOMEM);
diff --git a/mm/vma.h b/mm/vma.h
index eba388c61ef4..fe4560f81f4f 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -56,6 +56,7 @@ struct vma_munmap_struct {
enum vma_merge_state {
VMA_MERGE_START,
VMA_MERGE_ERROR_NOMEM,
+ VMA_MERGE_ERROR_INTR,
VMA_MERGE_NOMERGE,
VMA_MERGE_SUCCESS,
};
@@ -226,6 +227,11 @@ static inline bool vmg_nomem(struct vma_merge_struct *vmg)
return vmg->state == VMA_MERGE_ERROR_NOMEM;
}
+static inline bool vmg_intr(struct vma_merge_struct *vmg)
+{
+ return vmg->state == VMA_MERGE_ERROR_INTR;
+}
+
/* Assumes addr >= vma->vm_start. */
static inline pgoff_t vma_pgoff_offset(struct vm_area_struct *vma,
unsigned long addr)
--
2.53.0.414.gf7e9f6c205-goog
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