From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752214AbeCTCBI (ORCPT ); Mon, 19 Mar 2018 22:01:08 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45152 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752076AbeCTCAo (ORCPT ); Mon, 19 Mar 2018 22:00:44 -0400 From: jglisse@redhat.com To: linux-mm@kvack.org Cc: Andrew Morton , linux-kernel@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Evgeny Baskakov , Ralph Campbell , Mark Hairgrove , John Hubbard Subject: [PATCH 04/15] mm/hmm: unregister mmu_notifier when last HMM client quit Date: Mon, 19 Mar 2018 22:00:26 -0400 Message-Id: <20180320020038.3360-5-jglisse@redhat.com> In-Reply-To: <20180320020038.3360-1-jglisse@redhat.com> References: <20180320020038.3360-1-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jérôme Glisse This code was lost in translation at one point. This properly call mmu_notifier_unregister_no_release() once last user is gone. This fix the zombie mm_struct as without this patch we do not drop the refcount we have on it. Signed-off-by: Jérôme Glisse Cc: Evgeny Baskakov Cc: Ralph Campbell Cc: Mark Hairgrove Cc: John Hubbard --- mm/hmm.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/mm/hmm.c b/mm/hmm.c index 6088fa6ed137..667944630dc9 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -244,10 +244,29 @@ EXPORT_SYMBOL(hmm_mirror_register); void hmm_mirror_unregister(struct hmm_mirror *mirror) { struct hmm *hmm = mirror->hmm; + struct mm_struct *mm = NULL; + bool unregister = false; down_write(&hmm->mirrors_sem); list_del_init(&mirror->list); + unregister = list_empty(&hmm->mirrors); up_write(&hmm->mirrors_sem); + + if (!unregister) + return; + + spin_lock(&hmm->mm->page_table_lock); + if (hmm->mm->hmm == hmm) { + mm = hmm->mm; + mm->hmm = NULL; + } + spin_unlock(&hmm->mm->page_table_lock); + + if (mm == NULL) + return; + + mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm); + kfree(hmm); } EXPORT_SYMBOL(hmm_mirror_unregister); -- 2.14.3