From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [to-be-updated] kernel-fork-set-vmas-mm-prev-next-right-after-vm_area_dup-in-dup_mmap.patch removed from -mm tree Date: Thu, 09 Jan 2020 13:36:54 -0800 Message-ID: <20200109213654.mW9LBjpC9%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:45108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725775AbgAIVgz (ORCPT ); Thu, 9 Jan 2020 16:36:55 -0500 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: khlebnikov@yandex-team.ru, lixinhai.lxh@gmail.com, mm-commits@vger.kernel.org, richardw.yang@linux.intel.com, riel@redhat.com The patch titled Subject: kernel/fork: set VMA's mm/prev/next right after vm_area_dup in dup_mmap has been removed from the -mm tree. Its filename was kernel-fork-set-vmas-mm-prev-next-right-after-vm_area_dup-in-dup_mmap.patch This patch was dropped because an updated version will be merged ------------------------------------------------------ From: Konstantin Khlebnikov Subject: kernel/fork: set VMA's mm/prev/next right after vm_area_dup in dup_mmap Function vm_area_dup() makes exact copy of structure. It's better to stop referencing parent structures because various helpers use these pointers. For example if VM_WIPEONFORK is set then anon_vma_prepare() will try to merge anon_vma with previous and next VMA. Poking parent VMAs and sharing their anon_vma is safe for now but is not expected behavior. Note: this will break commit 4e4a9eb92133 ("mm/rmap.c: reuse mergeable anon_vma as parent when fork") without related fix because it contains several flaws hidden by current initialization sequence in dup_mmap(). Link: http://lkml.kernel.org/r/157839239842.694.2288178566540902852.stgit@buzz Signed-off-by: Konstantin Khlebnikov Reviewed-by: Li Xinhai Cc: Rik van Riel Cc: Wei Yang Cc: Konstantin Khlebnikov Signed-off-by: Andrew Morton --- kernel/fork.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/fork.c~kernel-fork-set-vmas-mm-prev-next-right-after-vm_area_dup-in-dup_mmap +++ a/kernel/fork.c @@ -544,10 +544,12 @@ static __latent_entropy int dup_mmap(str tmp = vm_area_dup(mpnt); if (!tmp) goto fail_nomem; + tmp->vm_mm = mm; + tmp->vm_prev = prev; + tmp->vm_next = NULL; retval = vma_dup_policy(mpnt, tmp); if (retval) goto fail_nomem_policy; - tmp->vm_mm = mm; retval = dup_userfaultfd(tmp, &uf); if (retval) goto fail_nomem_anon_vma_fork; @@ -559,7 +561,6 @@ static __latent_entropy int dup_mmap(str } else if (anon_vma_fork(tmp, mpnt, prev)) goto fail_nomem_anon_vma_fork; tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); - tmp->vm_next = tmp->vm_prev = NULL; file = tmp->vm_file; if (file) { struct inode *inode = file_inode(file); @@ -592,7 +593,6 @@ static __latent_entropy int dup_mmap(str */ *pprev = tmp; pprev = &tmp->vm_next; - tmp->vm_prev = prev; prev = tmp; __vma_link_rb(mm, tmp, rb_link, rb_parent); _ Patches currently in -mm which might be from khlebnikov@yandex-team.ru are