linux-kernel - [RFC PATCH 10/28] mm/mmap: mark VMAs as locked in vma

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Message-ID: <20220829212531.3184856-11-surenb@google.com>
Date:   Mon, 29 Aug 2022 21:25:13 +0000
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
        vbabka@...e.cz, hannes@...xchg.org, mgorman@...hsingularity.net,
        dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com,
        peterz@...radead.org, ldufour@...ux.ibm.com,
        laurent.dufour@...ibm.com, paulmck@...nel.org, riel@...riel.com,
        luto@...nel.org, songliubraving@...com, peterx@...hat.com,
        david@...hat.com, dhowells@...hat.com, hughd@...gle.com,
        bigeasy@...utronix.de, kent.overstreet@...ux.dev,
        rientjes@...gle.com, axelrasmussen@...gle.com, joelaf@...gle.com,
        minchan@...gle.com, surenb@...gle.com, kernel-team@...roid.com,
        linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH 10/28] mm/mmap: mark VMAs as locked in vma_adjust

vma_adjust modifies a VMA and possibly its neighbors. Mark them as locked
before making the modifications.

Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
 mm/mmap.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index f89c9b058105..ed58cf0689b2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -710,6 +710,10 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 	long adjust_next = 0;
 	int remove_next = 0;
 
+	vma_mark_locked(vma);
+	if (next)
+		vma_mark_locked(next);
+
 	if (next && !insert) {
 		struct vm_area_struct *exporter = NULL, *importer = NULL;
 
@@ -754,8 +758,11 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			 * If next doesn't have anon_vma, import from vma after
 			 * next, if the vma overlaps with it.
 			 */
-			if (remove_next == 2 && !next->anon_vma)
+			if (remove_next == 2 && !next->anon_vma) {
 				exporter = next->vm_next;
+				if (exporter)
+					vma_mark_locked(exporter);
+			}
 
 		} else if (end > next->vm_start) {
 			/*
@@ -931,6 +938,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			 * "vma->vm_next" gap must be updated.
 			 */
 			next = vma->vm_next;
+			if (next)
+				vma_mark_locked(next);
 		} else {
 			/*
 			 * For the scope of the comment "next" and
-- 
2.37.2.672.g94769d06f0-goog