From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f41.google.com (mail-qg0-f41.google.com [209.85.192.41]) by kanga.kvack.org (Postfix) with ESMTP id 1F1A46B0036 for ; Thu, 17 Jul 2014 14:47:17 -0400 (EDT) Received: by mail-qg0-f41.google.com with SMTP id q107so2390247qgd.28 for ; Thu, 17 Jul 2014 11:47:16 -0700 (PDT) Received: from mail-qc0-x231.google.com (mail-qc0-x231.google.com [2607:f8b0:400d:c01::231]) by mx.google.com with ESMTPS id t73si3492513qge.118.2014.07.17.11.47.16 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 17 Jul 2014 11:47:16 -0700 (PDT) Received: by mail-qc0-f177.google.com with SMTP id o8so2457530qcw.22 for ; Thu, 17 Jul 2014 11:47:16 -0700 (PDT) From: j.glisse@gmail.com Subject: [PATCH 1/7] mmu_notifier: add call_srcu and sync function for listener to delay call and sync. Date: Thu, 17 Jul 2014 14:46:47 -0400 Message-Id: <1405622809-3797-2-git-send-email-j.glisse@gmail.com> In-Reply-To: <1405622809-3797-1-git-send-email-j.glisse@gmail.com> References: <1405622809-3797-1-git-send-email-j.glisse@gmail.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-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org Cc: Linus Torvalds , joro@8bytes.org, Mel Gorman , "H. Peter Anvin" , Peter Zijlstra , Andrea Arcangeli , Johannes Weiner , Larry Woodman , Rik van Riel , Dave Airlie , Brendan Conoboy , Joe Donohue , Duncan Poole , Sherry Cheung , Subhash Gutti , John Hubbard , Mark Hairgrove , Lucien Dunning , Cameron Buschardt , Arvind Gopalakrishnan , Shachar Raindel , Liran Liss , Roland Dreier , Ben Sander , Greg Stoner , John Bridgman , Michael Mantor , Paul Blinzer , Laurent Morichetti , Alexander Deucher , Oded Gabbay , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= From: Peter Zijlstra New mmu_notifier listener are eager to cleanup there structure after the mmu_notifier::release callback. In order to allow this the patch provide a function that allows to add a delayed call to the mmu_notifier srcu. It also add a function that will call barrier_srcu so those listener can sync with mmu_notifier. Signed-off-by: Peter Zijlstra Signed-off-by: JA(C)rA'me Glisse --- include/linux/mmu_notifier.h | 6 ++++++ mm/mmu_notifier.c | 40 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 45 insertions(+), 1 deletion(-) diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index deca874..2728869 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -170,6 +170,8 @@ extern int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm); extern void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm); +extern void mmu_notifier_unregister_no_release(struct mmu_notifier *mn, + struct mm_struct *mm); extern void __mmu_notifier_mm_destroy(struct mm_struct *mm); extern void __mmu_notifier_release(struct mm_struct *mm); extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm, @@ -288,6 +290,10 @@ static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) set_pte_at(___mm, ___address, __ptep, ___pte); \ }) +extern void mmu_notifier_call_srcu(struct rcu_head *rcu, + void (*func)(struct rcu_head *rcu)); +extern void mmu_notifier_synchronize(void); + #else /* CONFIG_MMU_NOTIFIER */ static inline void mmu_notifier_release(struct mm_struct *mm) diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 41cefdf..950813b 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -23,6 +23,25 @@ static struct srcu_struct srcu; /* + * This function allows mmu_notifier::release callback to delay a call to + * a function that will free appropriate resources. The function must be + * quick and must not block. + */ +void mmu_notifier_call_srcu(struct rcu_head *rcu, + void (*func)(struct rcu_head *rcu)) +{ + call_srcu(&srcu, rcu, func); +} +EXPORT_SYMBOL_GPL(mmu_notifier_call_srcu); + +void mmu_notifier_synchronize(void) +{ + /* Wait for any running method to finish. */ + srcu_barrier(&srcu); +} +EXPORT_SYMBOL_GPL(mmu_notifier_synchronize); + +/* * This function can't run concurrently against mmu_notifier_register * because mm->mm_users > 0 during mmu_notifier_register and exit_mmap * runs with mm_users == 0. Other tasks may still invoke mmu notifiers @@ -53,7 +72,6 @@ void __mmu_notifier_release(struct mm_struct *mm) */ if (mn->ops->release) mn->ops->release(mn, mm); - srcu_read_unlock(&srcu, id); spin_lock(&mm->mmu_notifier_mm->lock); while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) { @@ -69,6 +87,7 @@ void __mmu_notifier_release(struct mm_struct *mm) hlist_del_init_rcu(&mn->hlist); } spin_unlock(&mm->mmu_notifier_mm->lock); + srcu_read_unlock(&srcu, id); /* * synchronize_srcu here prevents mmu_notifier_release from returning to @@ -325,6 +344,25 @@ void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm) } EXPORT_SYMBOL_GPL(mmu_notifier_unregister); +/* + * Same as mmu_notifier_unregister but no callback and no srcu synchronization. + */ +void mmu_notifier_unregister_no_release(struct mmu_notifier *mn, + struct mm_struct *mm) +{ + spin_lock(&mm->mmu_notifier_mm->lock); + /* + * Can not use list_del_rcu() since __mmu_notifier_release + * can delete it before we hold the lock. + */ + hlist_del_init_rcu(&mn->hlist); + spin_unlock(&mm->mmu_notifier_mm->lock); + + BUG_ON(atomic_read(&mm->mm_count) <= 0); + mmdrop(mm); +} +EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release); + static int __init mmu_notifier_init(void) { return init_srcu_struct(&srcu); -- 1.9.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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