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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
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CC:     Song Liu <songliubraving@fb.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
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        Laurent Dufour <ldufour@linux.ibm.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Rik van Riel <riel@surriel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Michel Lespinasse <walken.cr@gmail.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH 68/94] ipc/shm: Stop using the vma linked list
Thread-Topic: [PATCH 68/94] ipc/shm: Stop using the vma linked list
Thread-Index: AQHXPEQ9aZ/+Ako2W0eO8l+KHRK1lA==
Date:   Wed, 28 Apr 2021 15:36:21 +0000
Message-ID: <20210428153542.2814175-69-Liam.Howlett@Oracle.com>
References: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>
In-Reply-To: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>
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When searching for a VMA, a maple state can be used instead of the linked l=
ist in
the mm_struct

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 ipc/shm.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index febd88daba8c..e26da39eccb5 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1631,6 +1631,7 @@ long ksys_shmdt(char __user *shmaddr)
 	loff_t size =3D 0;
 	struct file *file;
 	struct vm_area_struct *next;
+	MA_STATE(mas, &mm->mm_mt, addr, addr);
 #endif
=20
 	if (addr & ~PAGE_MASK)
@@ -1660,11 +1661,11 @@ long ksys_shmdt(char __user *shmaddr)
 	 * match the usual checks anyway. So assume all vma's are
 	 * above the starting address given.
 	 */
-	vma =3D find_vma(mm, addr);
=20
 #ifdef CONFIG_MMU
+	vma =3D mas_find(&mas, ULONG_MAX);
 	while (vma) {
-		next =3D vma->vm_next;
+		next =3D mas_find(&mas, ULONG_MAX);
=20
 		/*
 		 * Check if the starting address would match, i.e. it's
@@ -1703,21 +1704,21 @@ long ksys_shmdt(char __user *shmaddr)
 	 */
 	size =3D PAGE_ALIGN(size);
 	while (vma && (loff_t)(vma->vm_end - addr) <=3D size) {
-		next =3D vma->vm_next;
-
 		/* finding a matching vma now does not alter retval */
 		if ((vma->vm_ops =3D=3D &shm_vm_ops) &&
 		    ((vma->vm_start - addr)/PAGE_SIZE =3D=3D vma->vm_pgoff) &&
 		    (vma->vm_file =3D=3D file))
 			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
-		vma =3D next;
+
+		vma =3D mas_find(&mas, addr + size - 1);
 	}
=20
 #else	/* CONFIG_MMU */
+	vma =3D mas_walk(&mas);
 	/* under NOMMU conditions, the exact address to be destroyed must be
 	 * given
 	 */
-	if (vma && vma->vm_start =3D=3D addr && vma->vm_ops =3D=3D &shm_vm_ops) {
+	if (vma && vma->vm_ops =3D=3D &shm_vm_ops) {
 		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
 		retval =3D 0;
 	}
--=20
2.30.2