[RFC PATCH RESEND 07/28] kernel/fork: mark VMAs as locked before copying pages during fork

From: Suren Baghdasaryan
Date: Thu Sep 01 2022 - 13:36:49 EST


Protect VMAs from concurrent page fault handler while performing
copy_page_range for VMAs having VM_WIPEONFORK flag set.

Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
kernel/fork.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index bfab31ecd11e..1872ad549fed 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -709,8 +709,10 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
rb_parent = &tmp->vm_rb;

mm->map_count++;
- if (!(tmp->vm_flags & VM_WIPEONFORK))
+ if (!(tmp->vm_flags & VM_WIPEONFORK)) {
+ vma_mark_locked(mpnt);
retval = copy_page_range(tmp, mpnt);
+ }

if (tmp->vm_ops && tmp->vm_ops->open)
tmp->vm_ops->open(tmp);
--
2.37.2.789.g6183377224-goog