Resubmitting 1GB page shm patchkit

Resubmitting 1GB page shm patchkit

[Andi Kleen]

This patchkit allows to specify 1GB (and other) page sizes with
shmget(). This is useful for programs who are difficult to modify
to use mmap.

I got positive reviews last time I submitted this. I also get 
requests from various users who want it. So here's a resend with:

- Rebased to current mainline
- Retested
- Fixed a minor umount problem.

Please consider for merging.

-Andi


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[PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v3

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

There was some desire in large applications using MAP_HUGETLB/SHM_HUGETLB
to use 1GB huge pages on some mappings, and stay with 2MB on others. This
is useful together with NUMA policy: use 2MB interleaving on some mappings,
but 1GB on local mappings.

This patch extends the IPC/SHM syscall interfaces slightly to allow specifying
the page size.

It borrows some upper bits in the existing flag arguments and allows encoding
the log of the desired page size in addition to the *_HUGETLB flag.
When 0 is specified the default size is used, this makes the change fully
compatible.

Extending the internal hugetlb code to handle this is straight forward. Instead
of a single mount it just keeps an array of them and selects the right
mount based on the specified page size.

I also exported the new flags to the user headers
(they were previously under __KERNEL__). Right now only symbols
for x86 and some other architecture for 1GB and 2MB are defined.
The interface should already work for all other architectures
though.

v2: Port to new tree. Fix unmount.
v3: Ported to latest tree.
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/mman.h |    3 ++
 fs/hugetlbfs/inode.c        |   63 ++++++++++++++++++++++++++++++++++---------
 include/asm-generic/mman.h  |   13 +++++++++
 include/linux/hugetlb.h     |   12 +++++++-
 include/linux/shm.h         |   19 +++++++++++++
 ipc/shm.c                   |    3 +-
 mm/mmap.c                   |    5 ++-
 7 files changed, 100 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/mman.h b/arch/x86/include/asm/mman.h
index 593e51d..513b05f 100644
--- a/arch/x86/include/asm/mman.h
+++ b/arch/x86/include/asm/mman.h
@@ -3,6 +3,9 @@
 
 #define MAP_32BIT	0x40		/* only give out 32bit addresses */
 
+#define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)
+#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)
+
 #include <asm-generic/mman.h>
 
 #endif /* _ASM_X86_MMAN_H */
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 9460120..f6fb699 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -924,7 +924,7 @@ static struct file_system_type hugetlbfs_fs_type = {
 	.kill_sb	= kill_litter_super,
 };
 
-static struct vfsmount *hugetlbfs_vfsmount;
+static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
 
 static int can_do_hugetlb_shm(void)
 {
@@ -933,9 +933,22 @@ static int can_do_hugetlb_shm(void)
 	return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
 }
 
+static int get_hstate_idx(int page_size_log)
+{
+	struct hstate *h;
+
+	if (!page_size_log)
+		return default_hstate_idx;
+	h = size_to_hstate(1 << page_size_log);
+	if (!h)
+		return -1;
+	return h - hstates;
+}
+
 struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 				size_t size, vm_flags_t acctflag,
-				struct user_struct **user, int creat_flags)
+				struct user_struct **user,
+				int creat_flags, int page_size_log)
 {
 	int error = -ENOMEM;
 	struct file *file;
@@ -945,9 +958,14 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 	struct qstr quick_string;
 	struct hstate *hstate;
 	unsigned long num_pages;
+	int hstate_idx;
+
+	hstate_idx = get_hstate_idx(page_size_log);
+	if (hstate_idx < 0)
+		return ERR_PTR(-ENODEV);
 
 	*user = NULL;
-	if (!hugetlbfs_vfsmount)
+	if (!hugetlbfs_vfsmount[hstate_idx])
 		return ERR_PTR(-ENOENT);
 
 	if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
@@ -964,7 +982,7 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 		}
 	}
 
-	root = hugetlbfs_vfsmount->mnt_root;
+	root = hugetlbfs_vfsmount[hstate_idx]->mnt_root;
 	quick_string.name = name;
 	quick_string.len = strlen(quick_string.name);
 	quick_string.hash = 0;
@@ -972,7 +990,7 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 	if (!path.dentry)
 		goto out_shm_unlock;
 
-	path.mnt = mntget(hugetlbfs_vfsmount);
+	path.mnt = mntget(hugetlbfs_vfsmount[hstate_idx]);
 	error = -ENOSPC;
 	inode = hugetlbfs_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0);
 	if (!inode)
@@ -1012,8 +1030,9 @@ out_shm_unlock:
 
 static int __init init_hugetlbfs_fs(void)
 {
+	struct hstate *h;
 	int error;
-	struct vfsmount *vfsmount;
+	int i;
 
 	error = bdi_init(&hugetlbfs_backing_dev_info);
 	if (error)
@@ -1030,14 +1049,26 @@ static int __init init_hugetlbfs_fs(void)
 	if (error)
 		goto out;
 
-	vfsmount = kern_mount(&hugetlbfs_fs_type);
+	i = 0;
+	for_each_hstate (h) {
+		char buf[50];
+		unsigned ps_kb = 1U << (h->order + PAGE_SHIFT - 10);
 
-	if (!IS_ERR(vfsmount)) {
-		hugetlbfs_vfsmount = vfsmount;
-		return 0;
-	}
+		snprintf(buf, sizeof buf, "pagesize=%uK", ps_kb);
+		hugetlbfs_vfsmount[i] = kern_mount_data(&hugetlbfs_fs_type,
+							buf);
 
-	error = PTR_ERR(vfsmount);
+		if (IS_ERR(hugetlbfs_vfsmount[i])) {
+				pr_err(
+			"hugetlb: Cannot mount internal hugetlbfs for page size %uK",
+			       ps_kb);
+			error = PTR_ERR(hugetlbfs_vfsmount[i]);
+		}
+		i++;
+	}
+	/* Non default hstates are optional */
+	if (hugetlbfs_vfsmount[default_hstate_idx])
+		return 0;
 
  out:
 	kmem_cache_destroy(hugetlbfs_inode_cachep);
@@ -1048,13 +1079,19 @@ static int __init init_hugetlbfs_fs(void)
 
 static void __exit exit_hugetlbfs_fs(void)
 {
+	struct hstate *h;
+	int i;
+
+
 	/*
 	 * Make sure all delayed rcu free inodes are flushed before we
 	 * destroy cache.
 	 */
 	rcu_barrier();
 	kmem_cache_destroy(hugetlbfs_inode_cachep);
-	kern_unmount(hugetlbfs_vfsmount);
+	i = 0;
+	for_each_hstate (h)
+		kern_unmount(hugetlbfs_vfsmount[i++]);
 	unregister_filesystem(&hugetlbfs_fs_type);
 	bdi_destroy(&hugetlbfs_backing_dev_info);
 }
diff --git a/include/asm-generic/mman.h b/include/asm-generic/mman.h
index 32c8bd6..d2f35d8 100644
--- a/include/asm-generic/mman.h
+++ b/include/asm-generic/mman.h
@@ -13,6 +13,19 @@
 #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
 
+/* Bits [26:31] are reserved */
+
+/*
+ * When MAP_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
+ * This gives us 6 bits, which is enough until someone invents 128 bit address
+ * spaces.
+ *
+ * Assume these are all power of twos.
+ * When 0 use the default page size.
+ */
+#define MAP_HUGE_SHIFT  26
+#define MAP_HUGE_MASK   0x3f
+
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
 
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 2251648..c626a2a 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -183,7 +183,13 @@ extern const struct file_operations hugetlbfs_file_operations;
 extern const struct vm_operations_struct hugetlb_vm_ops;
 struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 				size_t size, vm_flags_t acct,
-				struct user_struct **user, int creat_flags);
+				struct user_struct **user, int creat_flags,
+				int page_size_log);
+int hugetlb_get_quota(struct address_space *mapping, long delta);
+void hugetlb_put_quota(struct address_space *mapping, long delta);
+
+int hugetlb_get_quota(struct address_space *mapping, long delta);
+void hugetlb_put_quota(struct address_space *mapping, long delta);
 
 static inline int is_file_hugepages(struct file *file)
 {
@@ -195,12 +201,14 @@ static inline int is_file_hugepages(struct file *file)
 	return 0;
 }
 
+
 #else /* !CONFIG_HUGETLBFS */
 
 #define is_file_hugepages(file)			0
 static inline struct file *
 hugetlb_file_setup(const char *name, unsigned long addr, size_t size,
-		vm_flags_t acctflag, struct user_struct **user, int creat_flags)
+		vm_flags_t acctflag, struct user_struct **user, int creat_flags,
+		int page_size_log)
 {
 	return ERR_PTR(-ENOSYS);
 }
diff --git a/include/linux/shm.h b/include/linux/shm.h
index edd0868..d2b0ce0 100644
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -100,12 +100,31 @@ struct shmid_kernel /* private to the kernel */
 	struct task_struct	*shm_creator;
 };
 
+#endif
+
 /* shm_mode upper byte flags */
 #define	SHM_DEST	01000	/* segment will be destroyed on last detach */
 #define SHM_LOCKED      02000   /* segment will not be swapped */
 #define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
 #define SHM_NORESERVE   010000  /* don't check for reservations */
 
+/* Bits [26:31] are reserved */
+
+/*
+ * When SHM_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
+ * This gives us 6 bits, which is enough until someone invents 128 bit address
+ * spaces.
+ *
+ * Assume these are all power of twos.
+ * When 0 use the default page size.
+ */
+#define SHM_HUGE_SHIFT  26
+#define SHM_HUGE_MASK   0x3f
+#define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
+#define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
+
+#ifdef __KERNEL__
+
 #ifdef CONFIG_SYSVIPC
 long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr,
 	      unsigned long shmlba);
diff --git a/ipc/shm.c b/ipc/shm.c
index dff40c9..4fa6d8f 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -495,7 +495,8 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 		if (shmflg & SHM_NORESERVE)
 			acctflag = VM_NORESERVE;
 		file = hugetlb_file_setup(name, 0, size, acctflag,
-					&shp->mlock_user, HUGETLB_SHMFS_INODE);
+				  &shp->mlock_user, HUGETLB_SHMFS_INODE,
+				(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 	} else {
 		/*
 		 * Do not allow no accounting for OVERCOMMIT_NEVER, even
diff --git a/mm/mmap.c b/mm/mmap.c
index 872441e..5eb3ba7 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1127,8 +1127,9 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 		 * memory so no accounting is necessary
 		 */
 		file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len,
-						VM_NORESERVE, &user,
-						HUGETLB_ANONHUGE_INODE);
+				VM_NORESERVE,
+				&user, HUGETLB_ANONHUGE_INODE,
+				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
 		if (IS_ERR(file))
 			return PTR_ERR(file);
 	}
-- 
1.7.7.6

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Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v3

[Andrew Morton]

On Wed,  3 Oct 2012 15:24:23 -0700
Andi Kleen <andi@firstfloor.org> wrote:

> From: Andi Kleen <ak@linux.intel.com>
> 
> There was some desire in large applications using MAP_HUGETLB/SHM_HUGETLB
> to use 1GB huge pages on some mappings, and stay with 2MB on others. This
> is useful together with NUMA policy: use 2MB interleaving on some mappings,
> but 1GB on local mappings.
> 
> This patch extends the IPC/SHM syscall interfaces slightly to allow specifying
> the page size.
> 
> It borrows some upper bits in the existing flag arguments and allows encoding
> the log of the desired page size in addition to the *_HUGETLB flag.
> When 0 is specified the default size is used, this makes the change fully
> compatible.
> 
> Extending the internal hugetlb code to handle this is straight forward. Instead
> of a single mount it just keeps an array of them and selects the right
> mount based on the specified page size.
> 
> I also exported the new flags to the user headers
> (they were previously under __KERNEL__). Right now only symbols
> for x86 and some other architecture for 1GB and 2MB are defined.
> The interface should already work for all other architectures
> though.

So some manpages need updating.  I'm not sure which - mmap(2) surely,
but which for the IPC change?

> v2: Port to new tree. Fix unmount.
> v3: Ported to latest tree.
> Acked-by: Rik van Riel <riel@redhat.com>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  arch/x86/include/asm/mman.h |    3 ++
>  fs/hugetlbfs/inode.c        |   63 ++++++++++++++++++++++++++++++++++---------
>  include/asm-generic/mman.h  |   13 +++++++++
>  include/linux/hugetlb.h     |   12 +++++++-
>  include/linux/shm.h         |   19 +++++++++++++
>  ipc/shm.c                   |    3 +-
>  mm/mmap.c                   |    5 ++-

Alas, include/asm-generic/mman.h doesn't exist now.

Does this change touch all the hugetlb-capable architectures?

z:/usr/src/linux-3.6> grep -rl MAP_HUGETLB arch
arch/alpha/include/asm/mman.h
arch/xtensa/include/asm/mman.h
arch/parisc/include/asm/mman.h
arch/tile/include/asm/mman.h
arch/sparc/include/asm/mman.h
arch/powerpc/include/asm/mman.h
arch/mips/include/asm/mman.h

>
> ...
>
> @@ -933,9 +933,22 @@ static int can_do_hugetlb_shm(void)
>  	return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
>  }
>  
> +static int get_hstate_idx(int page_size_log)

nitlet: "page_size_order" would be more kernely.  Or just "page_order".

> +{
> +	struct hstate *h;
> +
> +	if (!page_size_log)
> +		return default_hstate_idx;
> +	h = size_to_hstate(1 << page_size_log);
> +	if (!h)
> +		return -1;
> +	return h - hstates;
> +}
>
> ...
>
>  static int __init init_hugetlbfs_fs(void)
>  {
> +	struct hstate *h;
>  	int error;
> -	struct vfsmount *vfsmount;
> +	int i;
>  
>  	error = bdi_init(&hugetlbfs_backing_dev_info);
>  	if (error)
> @@ -1030,14 +1049,26 @@ static int __init init_hugetlbfs_fs(void)
>  	if (error)
>  		goto out;
>  
> -	vfsmount = kern_mount(&hugetlbfs_fs_type);
> +	i = 0;
> +	for_each_hstate (h) {
> +		char buf[50];
> +		unsigned ps_kb = 1U << (h->order + PAGE_SHIFT - 10);
>  
> -	if (!IS_ERR(vfsmount)) {
> -		hugetlbfs_vfsmount = vfsmount;
> -		return 0;
> -	}
> +		snprintf(buf, sizeof buf, "pagesize=%uK", ps_kb);
> +		hugetlbfs_vfsmount[i] = kern_mount_data(&hugetlbfs_fs_type,
> +							buf);
>  
> -	error = PTR_ERR(vfsmount);
> +		if (IS_ERR(hugetlbfs_vfsmount[i])) {
> +				pr_err(
> +			"hugetlb: Cannot mount internal hugetlbfs for page size %uK",
> +			       ps_kb);
> +			error = PTR_ERR(hugetlbfs_vfsmount[i]);
> +		}
> +		i++;
> +	}
> +	/* Non default hstates are optional */
> +	if (hugetlbfs_vfsmount[default_hstate_idx])
> +		return 0;

hm, so if I'm understanding this, the patch mounts hugetlbfs N times,
once for each page size.  And presumably the shm code somehow selects
one of these mounts, based on incoming flags.  And presumably if those
flags are all-zero, the behaviour is unaltered.

Please update the changelog to describe all this - the overview of how
the patch actually operates.

Also, all this affects the /proc/mounts contents, yes?  Let's changelog
that very-slightly-non-back-compatible user-visible change as well.

There's some overhead to doing all those additional mounts.  Can we
quantify it?

>
> ...
>

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Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v3

[Andi Kleen]

Thanks for the review.

> > I also exported the new flags to the user headers
> > (they were previously under __KERNEL__). Right now only symbols
> > for x86 and some other architecture for 1GB and 2MB are defined.
> > The interface should already work for all other architectures
> > though.
> 
> So some manpages need updating.  I'm not sure which - mmap(2) surely,
> but which for the IPC change?

mmap and shmget. Was already planned.

> 
> > v2: Port to new tree. Fix unmount.
> > v3: Ported to latest tree.
> > Acked-by: Rik van Riel <riel@redhat.com>
> > Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > ---
> >  arch/x86/include/asm/mman.h |    3 ++
> >  fs/hugetlbfs/inode.c        |   63 ++++++++++++++++++++++++++++++++++---------
> >  include/asm-generic/mman.h  |   13 +++++++++
> >  include/linux/hugetlb.h     |   12 +++++++-
> >  include/linux/shm.h         |   19 +++++++++++++
> >  ipc/shm.c                   |    3 +-
> >  mm/mmap.c                   |    5 ++-
> 
> Alas, include/asm-generic/mman.h doesn't exist now.
> 
> Does this change touch all the hugetlb-capable architectures?

Right now only symbols
for x86 and some other architecture for 1GB and 2MB are defined.
The interface should already work for all other architectures
though.

So they can add new symbols for their page sizes at their leisure.

> >  	return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
> >  }
> >  
> > +static int get_hstate_idx(int page_size_log)
> 
> nitlet: "page_size_order" would be more kernely.  Or just "page_order".

It's not really an order, just the index.  I think I would prefer the current name,
order would be misleading.

For x86 it's only 0 and 1

> > +		if (IS_ERR(hugetlbfs_vfsmount[i])) {
> > +				pr_err(
> > +			"hugetlb: Cannot mount internal hugetlbfs for page size %uK",
> > +			       ps_kb);
> > +			error = PTR_ERR(hugetlbfs_vfsmount[i]);
> > +		}
> > +		i++;
> > +	}
> > +	/* Non default hstates are optional */
> > +	if (hugetlbfs_vfsmount[default_hstate_idx])
> > +		return 0;
> 
> hm, so if I'm understanding this, the patch mounts hugetlbfs N times,
> once for each page size.  And presumably the shm code somehow selects
> one of these mounts, based on incoming flags.  And presumably if those
> flags are all-zero, the behaviour is unaltered.

Yes.

> 
> Please update the changelog to describe all this - the overview of how
> the patch actually operates.

Ok.

> 
> Also, all this affects the /proc/mounts contents, yes?  Let's changelog
> that very-slightly-non-back-compatible user-visible change as well.

AFAIK not. The internal mounts are not visible. At least my laptop
doesn't show them.

> There's some overhead to doing all those additional mounts.  Can we
> quantify it?

On x86 it's one more mount (1GB). AFAIK it's just the sb structure, there's
nothing else preallocated. Maybe a couple hundred bytes per page size.

The number of huge page sizes is normally small, I don't think any architecture
has a large number.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only

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Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v3

[Andi Kleen]

> Alas, include/asm-generic/mman.h doesn't exist now.

git resolved it automagically

> 
> Does this change touch all the hugetlb-capable architectures?

I took a look at this again. So not every hugetlb capable architecture
needs it, only architectures with multiple hugetlb page sizes.

This is only x86, tile, powerpc

I looked at tile and powerpc and they both have configurable
hugetlb page sizes. So it's somewhat awkward to add defines
for them.

One disadvantage of this is also the user programs would need
to know the page sizes that are configured. That is definitely
awkward, but I don't know of any way around that.

Luckily there's a way in /sys to query this.

-Andi

> 
> z:/usr/src/linux-3.6> grep -rl MAP_HUGETLB arch
> arch/alpha/include/asm/mman.h
> arch/xtensa/include/asm/mman.h
> arch/parisc/include/asm/mman.h
> arch/tile/include/asm/mman.h
> arch/sparc/include/asm/mman.h
> arch/powerpc/include/asm/mman.h
> arch/mips/include/asm/mman.h

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