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Shutemov" Subject: [PATCH] mm/rmap.c: remove useless checking to child vma->vm_prev in anon_vma_clone For fork case, the dst->vm_prev is always same as src->vm_prev when anon_vma_clone() is called. Removing the assignment from dst->vm_prev->anon_vma to dst->anon_vma, and explictly assign from anon_vma which is shared by its parent vmas. Date: Mon, 6 Jan 2020 06:32:31 +0000 Message-Id: <1578292351-2501-1-git-send-email-lixinhai.lxh@gmail.com> X-Mailer: git-send-email 1.8.3.1 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000042, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Signed-off-by: Li Xinhai Cc: Wei Yang Cc: Konstantin Khlebnikov Cc: Kirill A. Shutemov --- mm/rmap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index b3e3819..3c912a6c 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -269,10 +269,10 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) { struct anon_vma_chain *avc, *pavc; struct anon_vma *root = NULL; - struct vm_area_struct *prev = dst->vm_prev, *pprev = src->vm_prev; + struct vm_area_struct *pprev = src->vm_prev; /* - * If parent share anon_vma with its vm_prev, keep this sharing in in + * If parent share anon_vma with its vm_prev, keep this sharing in * child. * * 1. Parent has vm_prev, which implies we have vm_prev. @@ -280,8 +280,7 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) */ if (!dst->anon_vma && src->anon_vma && pprev && pprev->anon_vma == src->anon_vma) - dst->anon_vma = prev->anon_vma; - + dst->anon_vma = pprev->anon_vma; list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { struct anon_vma *anon_vma; -- 1.8.3.1