From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx130.postini.com [74.125.245.130]) by kanga.kvack.org (Postfix) with SMTP id 6BB5B6B002C for ; Sun, 5 Feb 2012 05:25:12 -0500 (EST) Message-ID: <4F2E5853.2060605@mellanox.com> Date: Sun, 5 Feb 2012 12:22:11 +0200 From: sagig MIME-Version: 1.0 Subject: Re: [PATCH RFC] mm: convert rcu_read_lock() to srcu_read_lock(), thus allowing to sleep in callbacks References: <4f25649b.8253b40a.3800.319d@mx.google.com> In-Reply-To: <4f25649b.8253b40a.3800.319d@mx.google.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: aarcange@redhat.com Cc: gleb@redhat.com, oren@mellanox.com, ogerlitz@mellanox.com, linux-mm@kvack.org Hey all, I've published this patch [requested for comments] last week, But got no responses. Since I'm not sure what to do if init_srcu_struct() call fails (it might due to memory pressure), I'm interested in the community's advice on how to act. Thanks, On 1/29/2012 5:23 PM, sagig@mellanox.com wrote: > Callbacks: invalidate_page, invalidate_range_start/end, change_pte > Now that anon_vma lock and i_mmap_mutex are both sleepable mutex, it is possible to schedule inside invalidation cllabacks > This is essential for a scheduling HW sync in RDMA drivers which apply on demand paging methods > > Signed-off-by: sagi grimberg > --- > mm/mmu_notifier.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++------ > 1 files changed, 55 insertions(+), 8 deletions(-) > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index 9a611d3..70dadd5 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -123,10 +123,16 @@ int __mmu_notifier_test_young(struct mm_struct *mm, > void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, > pte_t pte) > { > + int idx = -1; > + struct srcu_struct srcu; > struct mmu_notifier *mn; > struct hlist_node *n; > > - rcu_read_lock(); > + if (init_srcu_struct(&srcu)) > + rcu_read_lock(); > + else > + idx = srcu_read_lock(&srcu); > + > hlist_for_each_entry_rcu(mn, n,&mm->mmu_notifier_mm->list, hlist) { > if (mn->ops->change_pte) > mn->ops->change_pte(mn, mm, address, pte); > @@ -137,49 +143,90 @@ void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, > else if (mn->ops->invalidate_page) > mn->ops->invalidate_page(mn, mm, address); > } > - rcu_read_unlock(); > + > + if (idx< 0) > + rcu_read_unlock(); > + else > + srcu_read_unlock(&srcu, idx); > + > + cleanup_srcu_struct(&srcu); > } > > void __mmu_notifier_invalidate_page(struct mm_struct *mm, > unsigned long address) > { > + int idx = -1; > + struct srcu_struct srcu; > struct mmu_notifier *mn; > struct hlist_node *n; > > - rcu_read_lock(); > + if (init_srcu_struct(&srcu)) > + rcu_read_lock(); > + else > + idx = srcu_read_lock(&srcu); > + > hlist_for_each_entry_rcu(mn, n,&mm->mmu_notifier_mm->list, hlist) { > if (mn->ops->invalidate_page) > mn->ops->invalidate_page(mn, mm, address); > } > - rcu_read_unlock(); > + > + if (idx< 0) > + rcu_read_unlock(); > + else > + srcu_read_unlock(&srcu, idx); > + > + cleanup_srcu_struct(&srcu); > } > > void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, > unsigned long start, unsigned long end) > { > + int idx = -1; > + struct srcu_struct srcu; > struct mmu_notifier *mn; > struct hlist_node *n; > > - rcu_read_lock(); > + if (init_srcu_struct(&srcu)) > + rcu_read_lock(); > + else > + idx = srcu_read_lock(&srcu); > + > hlist_for_each_entry_rcu(mn, n,&mm->mmu_notifier_mm->list, hlist) { > if (mn->ops->invalidate_range_start) > mn->ops->invalidate_range_start(mn, mm, start, end); > } > - rcu_read_unlock(); > + > + if (idx< 0) > + rcu_read_unlock(); > + else > + srcu_read_unlock(&srcu, idx); > + > + cleanup_srcu_struct(&srcu); > } > > void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, > unsigned long start, unsigned long end) > { > + int idx = -1; > + struct srcu_struct srcu; > struct mmu_notifier *mn; > struct hlist_node *n; > > - rcu_read_lock(); > + if (init_srcu_struct(&srcu)) > + rcu_read_lock(); > + else > + idx = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(mn, n,&mm->mmu_notifier_mm->list, hlist) { > if (mn->ops->invalidate_range_end) > mn->ops->invalidate_range_end(mn, mm, start, end); > } > - rcu_read_unlock(); > + > + if (idx< 0) > + rcu_read_unlock(); > + else > + srcu_read_unlock(&srcu, idx); > + > + cleanup_srcu_struct(&srcu); > } > > static int do_mmu_notifier_register(struct mmu_notifier *mn, -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org