* [PATCH RFC] mm: convert rcu_read_lock() to srcu_read_lock(), thus allowing to sleep in callbacks
@ 2012-01-29 15:23 sagig
2012-02-05 10:22 ` sagig
0 siblings, 1 reply; 3+ messages in thread
From: sagig @ 2012-01-29 15:23 UTC (permalink / raw)
To: aarcange; +Cc: gleb, oren, ogerlitz, sagig, linux-mm, sagi grimberg
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 <sagig@mellanox.co.il>
---
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,
--
1.7.6.4
--
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^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH RFC] mm: convert rcu_read_lock() to srcu_read_lock(), thus allowing to sleep in callbacks
2012-01-29 15:23 [PATCH RFC] mm: convert rcu_read_lock() to srcu_read_lock(), thus allowing to sleep in callbacks sagig
@ 2012-02-05 10:22 ` sagig
2012-02-05 10:52 ` Konstantin Khlebnikov
0 siblings, 1 reply; 3+ messages in thread
From: sagig @ 2012-02-05 10:22 UTC (permalink / raw)
To: aarcange; +Cc: gleb, oren, ogerlitz, linux-mm
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<sagig@mellanox.co.il>
> ---
> 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,
--
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH RFC] mm: convert rcu_read_lock() to srcu_read_lock(), thus allowing to sleep in callbacks
2012-02-05 10:22 ` sagig
@ 2012-02-05 10:52 ` Konstantin Khlebnikov
0 siblings, 0 replies; 3+ messages in thread
From: Konstantin Khlebnikov @ 2012-02-05 10:52 UTC (permalink / raw)
To: sagig
Cc: aarcange@redhat.com, gleb@redhat.com, oren@mellanox.com,
ogerlitz@mellanox.com, linux-mm@kvack.org
sagig wrote:
> 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,
>
Your patch is completely wrong.
There must be one shared srcu_struct structure.
Please read how rcu works in Documentation/RCU/
Thanks.
--
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-01-29 15:23 [PATCH RFC] mm: convert rcu_read_lock() to srcu_read_lock(), thus allowing to sleep in callbacks sagig
2012-02-05 10:22 ` sagig
2012-02-05 10:52 ` Konstantin Khlebnikov
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