From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id 717A16B000D for ; Wed, 10 Oct 2018 08:53:41 -0400 (EDT) Received: by mail-pf1-f197.google.com with SMTP id 87-v6so4344716pfq.8 for ; Wed, 10 Oct 2018 05:53:41 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id w11-v6sor20337116pfk.56.2018.10.10.05.53.40 for (Google Transport Security); Wed, 10 Oct 2018 05:53:40 -0700 (PDT) From: Wei Yang Subject: [PATCH] mm: remove a redundant check in do_munmap() Date: Wed, 10 Oct 2018 20:53:27 +0800 Message-Id: <20181010125327.68803-1-richard.weiyang@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, mhocko@suse.com Cc: linux-mm@kvack.org, Wei Yang A non-NULL vma returned from find_vma() implies: vma->vm_start <= start Since len != 0, the following condition always hods: vma->vm_start < start + len = end This means the if check would never be true. This patch removes this redundant check and fix two typo in comment. Signed-off-by: Wei Yang --- mm/mmap.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 8d6449e74431..94660ddfa2c1 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -414,7 +414,7 @@ static void vma_gap_update(struct vm_area_struct *vma) { /* * As it turns out, RB_DECLARE_CALLBACKS() already created a callback - * function that does exacltly what we want. + * function that does exactly what we want. */ vma_gap_callbacks_propagate(&vma->vm_rb, NULL); } @@ -1621,7 +1621,7 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) #endif /* __ARCH_WANT_SYS_OLD_MMAP */ /* - * Some shared mappigns will want the pages marked read-only + * Some shared mappings will want the pages marked read-only * to track write events. If so, we'll downgrade vm_page_prot * to the private version (using protection_map[] without the * VM_SHARED bit). @@ -2705,12 +2705,8 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, if (!vma) return 0; prev = vma->vm_prev; - /* we have start < vma->vm_end */ - - /* if it doesn't overlap, we have nothing.. */ + /* we have vma->vm_start <= start < vma->vm_end */ end = start + len; - if (vma->vm_start >= end) - return 0; /* * If we need to split any vma, do it now to save pain later. -- 2.15.1