linux-kernel - [PATCH 50/94] mm/mmap: Change do_brk_munmap() to use do_mas_align

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Date:   Wed, 28 Apr 2021 15:36:13 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Liam Howlett <liam.howlett@...cle.com>
Subject: [PATCH 50/94] mm/mmap: Change do_brk_munmap() to use
 do_mas_align_munmap()

do_brk_munmap() already has aligned addresses.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mmap.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index cf4aa715eb63..3b1a9f6bc39b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2965,12 +2965,16 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 	struct mm_struct *mm = vma->vm_mm;
 	struct vm_area_struct unmap;
 	unsigned long unmap_pages;
-	int ret = 1;
+	int ret;
 
 	arch_unmap(mm, newbrk, oldbrk);
 
-	if (likely(vma->vm_start >= newbrk)) { // remove entire mapping(s)
-		ret = do_mas_munmap(mas, mm, newbrk, oldbrk-newbrk, uf, true);
+	if (likely((vma->vm_end < oldbrk) ||
+		   ((vma->vm_start == newbrk) && (vma->vm_end == oldbrk)))) {
+		// remove entire mapping(s)
+		mas->last = oldbrk - 1;
+		ret = do_mas_align_munmap(mas, vma, mm, newbrk, oldbrk, uf,
+					  true);
 		goto munmap_full_vma;
 	}
 
-- 
2.30.2