From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue, 16 Mar 2021 19:59:36 +0000 (-0400)
Subject: khugepaged rcu fix
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=06ba53390f6ee196261b09917e182c311a46e0de;p=users%2Fjedix%2Flinux-maple.git

khugepaged rcu fix

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

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 1e22a5a2e25d6..613f0bdc8b34d 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2099,6 +2099,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
 	mas_set(&mas, khugepaged_scan.address);
 	if (unlikely(!mmap_read_trylock(mm)))
 		goto breakouterloop_mmap_lock;
+
+	rcu_read_lock();
 	if (likely(!khugepaged_test_exit(mm)))
 		vma = mas_find(&mas, ULONG_MAX);
 
@@ -2142,6 +2144,7 @@ skip:
 				pgoff_t pgoff = linear_page_index(vma,
 						khugepaged_scan.address);
 
+				rcu_read_unlock();
 				mmap_read_unlock(mm);
 				ret = 1;
 				khugepaged_scan_file(mm, file, pgoff, hpage);
@@ -2162,6 +2165,7 @@ skip:
 		}
 	}
 breakouterloop:
+	rcu_unread_lock();
 	mmap_read_unlock(mm); /* exit_mmap will destroy ptes after this */
 breakouterloop_mmap_lock: