From: Sung-hun Kim <sfoon.kim@samsung.com>
Date: Fri, 1 Oct 2021 04:01:01 +0000 (+0900)
Subject: mm: thp: add acquisition/release of a lock to guarantee consistent locking state
X-Git-Tag: submit/tizen/20220208.074352~26
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ba78f1fc86a7bdfd875bbdafd4b66cac58638809;p=platform%2Fkernel%2Flinux-rpi.git

mm: thp: add acquisition/release of a lock to guarantee consistent locking state

arm64_wp_huge_pte should acquire a lock before return
to keep the lock semantics of the caller.
To guarantee this, add a new lock acquisition and a
new lock release statements in proper positions.

Change-Id: I81fb8afc37f54bce83f353ca6b6894e70ef86934
Signed-off-by: Sung-hun Kim <sfoon.kim@samsung.com>
---

diff --git a/arch/arm64/mm/huge_memory.c b/arch/arm64/mm/huge_memory.c
index 1073fde..4dbb11d 100644
--- a/arch/arm64/mm/huge_memory.c
+++ b/arch/arm64/mm/huge_memory.c
@@ -470,8 +470,12 @@ vm_fault_t arm64_wp_huge_pte(struct vm_fault *vmf, pte_t orig_pte)
 	pte_t *hpte_p;
 
 	if (vma_is_anonymous(vmf->vma)) {
+		int ret;
+
 		spin_unlock(vmf->ptl);
-		return arm64_do_huge_pte_wp_page(vmf, orig_pte);
+		ret = arm64_do_huge_pte_wp_page(vmf, orig_pte);
+		spin_lock(vmf->ptl);
+		return ret;
 	}
 
 	VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
diff --git a/mm/memory.c b/mm/memory.c
index e1924c1..6797a78 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4635,8 +4635,14 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
 		if (!pte_write(entry)) {
 			int ret = arch_do_wp_page(vmf, entry);
 
-			if (!(ret & VM_FAULT_FALLBACK))
+			if (!(ret & VM_FAULT_FALLBACK)) {
+				/*
+				 * arch_do_wp_page returns
+				 * VM_FAULT value with spin lock acquisition.
+				 */
+				spin_unlock(vmf->ptl);
 				return ret;
+			}
 			return do_wp_page(vmf);
 		}
 		if (arch_huge_pte_set_accessed(vmf, entry))