From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id CD2AC6B000D for ; Mon, 19 Mar 2018 22:00:44 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id t24so39970qtn.21 for ; Mon, 19 Mar 2018 19:00:44 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id e29si733357qta.14.2018.03.19.19.00.43 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Mar 2018 19:00:44 -0700 (PDT) From: jglisse@redhat.com 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: owner-linux-mm@kvack.org List-ID: 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 From: JA(C)rA'me 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: JA(C)rA'me 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