hugetlb: add locking for overcommit sysctl

PATCH In review Nishanth Aravamudan 2 participants 3 messages Feb 6, 2008 – Feb 7, 2008

Subsystems (3)

Memory management HugeTLB Proc sysctl

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Nishanth Aravamudan

author

2008-02-06 23:03 UTC #0 lore raw

PATCH 1/1 hugetlb: add locking for overcommit sysctl

When I replaced hugetlb_dynamic_pool with nr_overcommit_hugepages I used proc_doulongvec_minmax() directly. However, hugetlb.c's locking rules require that all counter modifications occur under the hugetlb_lock. Add a callback into the hugetlb code similar to the one for nr_hugepages. Grab the lock around the manipulation of nr_overcommit_hugepages in proc_doulongvec_minmax().

Signed-off-by Nishanth Aravamudan <[email protected]>

---
I noticed that the nr_hugepages sysctl uses a helper variable, max_huge_pages to do the same thing. Is that because of locking requirements (undocmented) for proc_doulongvec_minmax() or because of the more complicated manipulation of the pool state for that sysctl? If the former, I will need to modify this patch.

include/linux/hugetlb.h +1 -0

index 30d606a..7ca198b 100644
@@ -17,6 +17,7 @@ static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
 }
 
 int hugetlb_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
+int hugetlb_overcommit_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int hugetlb_treat_movable_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *);
 int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int);

kernel/sysctl.c +1 -1

index 5e2ad5b..92fef8d 100644
@@ -973,7 +973,7 @@ static struct ctl_table vm_table[] = {
 		.data		= &nr_overcommit_huge_pages,
 		.maxlen		= sizeof(nr_overcommit_huge_pages),
 		.mode		= 0644,
-		.proc_handler	= &proc_doulongvec_minmax,
+		.proc_handler	= &hugetlb_overcommit_handler,
 	},
 #endif
 	{

mm/hugetlb.c +10 -0

index 1a56420..d9a3803 100644
@@ -605,6 +605,16 @@ int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
 	return 0;
 }
 
+int hugetlb_overcommit_handler(struct ctl_table *table, int write,
+			struct file *file, void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	spin_lock(&hugetlb_lock);
+	proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
+	spin_unlock(&hugetlb_lock);
+	return 0;
+}
+
 #endif /* CONFIG_SYSCTL */
 
 int hugetlb_report_meminfo(char *buf)

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Adam Litke

Acked-by on v1 1/1

2008-02-07 15:14 UTC #1 lore raw

Quoted 8 lines · Nishanth Aravamudan

When I replaced hugetlb_dynamic_pool with nr_overcommit_hugepages I used proc_doulongvec_minmax() directly. However, hugetlb.c's locking rules require that all counter modifications occur under the hugetlb_lock. Add a callback into the hugetlb code similar to the one for nr_hugepages. Grab the lock around the manipulation of nr_overcommit_hugepages in proc_doulongvec_minmax().
Signed-off-by Nishanth Aravamudan <[email protected]>

Acked-by Adam Litke <[email protected]>

Quoted 54 lines

include/linux/hugetlb.h +1 -0

index 30d606a..7ca198b 100644
@@ -17,6 +17,7 @@ static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
 }
 
 int hugetlb_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
+int hugetlb_overcommit_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int hugetlb_treat_movable_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *);
 int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int);

kernel/sysctl.c +1 -1

index 5e2ad5b..92fef8d 100644
@@ -973,7 +973,7 @@ static struct ctl_table vm_table[] = {
 		.data		= &nr_overcommit_huge_pages,
 		.maxlen		= sizeof(nr_overcommit_huge_pages),
 		.mode		= 0644,
-		.proc_handler	= &proc_doulongvec_minmax,
+		.proc_handler	= &hugetlb_overcommit_handler,
 	},
 #endif
 	{

mm/hugetlb.c +10 -0

index 1a56420..d9a3803 100644
@@ -605,6 +605,16 @@ int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
 	return 0;
 }
 
+int hugetlb_overcommit_handler(struct ctl_table *table, int write,
+			struct file *file, void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	spin_lock(&hugetlb_lock);
+	proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
+	spin_unlock(&hugetlb_lock);
+	return 0;
+}
+
 #endif /* CONFIG_SYSCTL */
 
 int hugetlb_report_meminfo(char *buf)

Signature · 8 lines

Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center

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Nishanth Aravamudan

author

2008-02-07 16:51 UTC #2 lore raw

Quoted 11 lines · Adam Litke

Quoted 8 lines · Nishanth Aravamudan
When I replaced hugetlb_dynamic_pool with nr_overcommit_hugepages I used proc_doulongvec_minmax() directly. However, hugetlb.c's locking rules require that all counter modifications occur under the hugetlb_lock. Add a callback into the hugetlb code similar to the one for nr_hugepages. Grab the lock around the manipulation of nr_overcommit_hugepages in proc_doulongvec_minmax().
Signed-off-by Nishanth Aravamudan <[email protected]>
Acked-by Adam Litke <[email protected]>

Thanks, Adam.

Andrew, this is a bugfix for 2.6.25 and presumably should be backported to -stable once upstream (I'll keep my eye out for the commit message if it goes there).

Quoted 58 lines

Quoted 54 lines

include/linux/hugetlb.h +1 -0

index 30d606a..7ca198b 100644
@@ -17,6 +17,7 @@ static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
 }
 
 int hugetlb_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
+int hugetlb_overcommit_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int hugetlb_treat_movable_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *);
 int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int);

kernel/sysctl.c +1 -1

index 5e2ad5b..92fef8d 100644
@@ -973,7 +973,7 @@ static struct ctl_table vm_table[] = {
 		.data		= &nr_overcommit_huge_pages,
 		.maxlen		= sizeof(nr_overcommit_huge_pages),
 		.mode		= 0644,
-		.proc_handler	= &proc_doulongvec_minmax,
+		.proc_handler	= &hugetlb_overcommit_handler,
 	},
 #endif
 	{

mm/hugetlb.c +10 -0

index 1a56420..d9a3803 100644
@@ -605,6 +605,16 @@ int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
 	return 0;
 }
 
+int hugetlb_overcommit_handler(struct ctl_table *table, int write,
+			struct file *file, void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	spin_lock(&hugetlb_lock);
+	proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
+	spin_unlock(&hugetlb_lock);
+	return 0;
+}
+
 #endif /* CONFIG_SYSCTL */
 
 int hugetlb_report_meminfo(char *buf)

Signature · 2 lines

Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center

Signature · 8 lines

Nishanth Aravamudan <[email protected]>
IBM Linux Technology Center

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