From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue, 16 Mar 2021 19:59:04 +0000 (-0400)
Subject: fork rcu fix
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d2b9ddf82b553a7fda4bb2fe1989898e0739d050;p=users%2Fjedix%2Flinux-maple.git

fork rcu fix

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/kernel/fork.c b/kernel/fork.c
index 58bcee1c5854..d965b248c772 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -506,6 +506,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 	if (retval)
 		goto fail_nomem;
 
+	rcu_read_lock();
 	mas_for_each(&old_mas, mpnt, ULONG_MAX) {
 		struct file *file;
 
@@ -595,6 +596,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 	retval = arch_dup_mmap(oldmm, mm);
 loop_out:
 out:
+	rcu_read_unlock();
 	mmap_write_unlock(mm);
 	flush_tlb_mm(oldmm);
 	mmap_write_unlock(oldmm);