mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB

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.  When no page size is
specified it uses the mount of the default page size.

The change is not visible in /proc/mounts because internal mounts don't
appear there.  It also has very little overhead: the additional mounts
just consume a super block, but not more memory when not used.

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.  Only architectures that define
multiple hugetlb sizes actually need it (that is currently x86, tile,
powerpc).  However tile and powerpc have user configurable hugetlb sizes,
so it's not easy to add defines.  A program on those architectures would
need to query sysfs and use the appropiate log2.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/include/asm/mman.h b/arch/x86/include/asm/mman.h
index 593e51d4643f6adb403a756f11408835ce075355..513b05f15bb4f8cdeeb42369b18223ad506ded40 100644 (file)
--- 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 c5bc355d8243e36ba8ae322756f6a71277aa778b..f33227504387847f7a2ec35dc8c8908ae9156909 100644 (file)
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -923,7 +923,7 @@ 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)
 {
@@ -932,9 +932,22 @@ 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;
@@ -944,9 +957,14 @@ 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()) {
@@ -963,7 +981,7 @@ 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;
@@ -971,7 +989,7 @@ 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)
@@ -1011,8 +1029,9 @@ 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)
@@ -1029,14 +1048,27 @@ static int __init init_hugetlbfs_fs(void)
        if (error)
                goto out;
 
-       vfsmount = kern_mount(&hugetlbfs_fs_type);
-
-       if (!IS_ERR(vfsmount)) {
-               hugetlbfs_vfsmount = vfsmount;
-               return 0;
+       i = 0;
+       for_each_hstate (h) {
+               char buf[50];
+               unsigned ps_kb = 1U << (h->order + PAGE_SHIFT - 10);
+
+               snprintf(buf, sizeof buf, "pagesize=%uK", ps_kb);
+               hugetlbfs_vfsmount[i] = kern_mount_data(&hugetlbfs_fs_type,
+                                                       buf);
+
+               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]);
+                       hugetlbfs_vfsmount[i] = NULL;
+               }
+               i++;
        }
-
-       error = PTR_ERR(vfsmount);
+       /* Non default hstates are optional */
+       if (!IS_ERR_OR_NULL(hugetlbfs_vfsmount[default_hstate_idx]))
+               return 0;
 
  out:
        kmem_cache_destroy(hugetlbfs_inode_cachep);
@@ -1047,13 +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/linux/hugetlb.h b/include/linux/hugetlb.h
index 225164842ab62797216cd13c82c510d6847e13c4..3e7fa1acf09cdebb4f060b17bb293a30a1437206 100644 (file)
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -183,7 +183,8 @@ 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);
 
 static inline int is_file_hugepages(struct file *file)
 {
@@ -195,12 +196,14 @@ 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 bcf8a6a3ec00d51b08e113248a0ca62d56f8b542..7bbab55b0d0970be1ec34cb1e7aa52c2b4eb1123 100644 (file)
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -23,12 +23,31 @@ 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/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h
index 32c8bd6a196dffe0cc2cfd367792754faf88836e..d2f35d8d68c6122cfe7e5cbb67b878ab4d0c563e 100644 (file)
--- a/include/uapi/asm-generic/mman.h
+++ b/include/uapi/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/ipc/shm.c b/ipc/shm.c
index dff40c9f73c9df09544c057f7325004726d27715..4fa6d8fee730c05e3fe4e4fbb93fa40690ede3bc 100644 (file)
--- 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 9a796c41e7d9ecf8d474089df2d1b2235451ce3c..ebf19031c5e4b44eca898e1443ba9c541aa94f31 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1153,8 +1153,9 @@ 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);
        }