thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE

For file mappings, we don't deposit page tables on THP allocation
because it's not strictly required to implement split_huge_pmd(): we can
just clear pmd and let following page faults to reconstruct the page
table.

But Power makes use of deposited page table to address MMU quirk.

Let's hide THP page cache, including huge tmpfs, under separate config
option, so it can be forbidden on Power.

We can revert the patch later once solution for Power found.

Link: http://lkml.kernel.org/r/1466021202-61880-36-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 0890f700a5465712b5734f9f6575e86adf39393b..54fa28dfbd89d0e202f974bfa7d0270490e6f7d0 100644 (file)
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -54,7 +54,6 @@ extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
                unsigned long len, unsigned long pgoff, unsigned long flags);
 extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
 extern bool shmem_mapping(struct address_space *mapping);
-extern bool shmem_huge_enabled(struct vm_area_struct *vma);
 extern void shmem_unlock_mapping(struct address_space *mapping);
 extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
                                        pgoff_t index, gfp_t gfp_mask);
@@ -112,4 +111,13 @@ static inline long shmem_fcntl(struct file *f, unsigned int c, unsigned long a)
 
 #endif
 
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
+extern bool shmem_huge_enabled(struct vm_area_struct *vma);
+#else
+static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
+{
+       return false;
+}
+#endif
+
 #endif

diff --git a/mm/Kconfig b/mm/Kconfig
index 3e2daef3c946a117bbfa4e63fa6a4fb7bd31a5ad..3c81803b00a32c44690893758cf0bb35d6f4db95 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -439,6 +439,14 @@ choice
          benefit.
 endchoice
 
+#
+# We don't deposit page tables on file THP mapping,
+# but Power makes use of them to address MMU quirk.
+#
+config TRANSPARENT_HUGE_PAGECACHE
+       def_bool y
+       depends on TRANSPARENT_HUGEPAGE && !PPC
+
 #
 # UP and nommu archs use km based percpu allocator
 #

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2706182787d8a7a3d436f3150de62efa531f51ef..d3abbf249fa048b23f41f37960f4b90d7ba4779f 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -287,7 +287,7 @@ static struct attribute *hugepage_attr[] = {
        &enabled_attr.attr,
        &defrag_attr.attr,
        &use_zero_page_attr.attr,
-#ifdef CONFIG_SHMEM
+#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
        &shmem_enabled_attr.attr,
 #endif
 #ifdef CONFIG_DEBUG_VM

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 573e4366d3b9078f0b6759de0877cec26d6e3a1f..93d5f87c00d57c392e43c8bd1c1e5b0df15ca0bc 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -819,6 +819,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
            (vma->vm_flags & VM_NOHUGEPAGE))
                return false;
        if (shmem_file(vma->vm_file)) {
+               if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
+                       return false;
                return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
                                HPAGE_PMD_NR);
        }
@@ -1222,7 +1224,7 @@ static void collect_mm_slot(struct mm_slot *mm_slot)
        }
 }
 
-#ifdef CONFIG_SHMEM
+#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
 static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
 {
        struct vm_area_struct *vma;
@@ -1681,8 +1683,6 @@ skip:
                if (khugepaged_scan.address < hstart)
                        khugepaged_scan.address = hstart;
                VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
-               if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma))
-                       goto skip;
 
                while (khugepaged_scan.address < hend) {
                        int ret;
@@ -1694,9 +1694,12 @@ skip:
                                  khugepaged_scan.address + HPAGE_PMD_SIZE >
                                  hend);
                        if (shmem_file(vma->vm_file)) {
-                               struct file *file = get_file(vma->vm_file);
+                               struct file *file;
                                pgoff_t pgoff = linear_page_index(vma,
                                                khugepaged_scan.address);
+                               if (!shmem_huge_enabled(vma))
+                                       goto skip;
+                               file = get_file(vma->vm_file);
                                up_read(&mm->mmap_sem);
                                ret = 1;
                                khugepaged_scan_shmem(mm, file->f_mapping,

diff --git a/mm/memory.c b/mm/memory.c
index 712790e95f08629497d15b7fa02728475fefd4dc..4425b605933900b7f42856bfcd3ad05a46bd0959 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2920,7 +2920,7 @@ map_pte:
        return 0;
 }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 
 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
@@ -3002,7 +3002,8 @@ int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
        pte_t entry;
        int ret;
 
-       if (pmd_none(*fe->pmd) && PageTransCompound(page)) {
+       if (pmd_none(*fe->pmd) && PageTransCompound(page) &&
+                       IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
                /* THP on COW? */
                VM_BUG_ON_PAGE(memcg, page);
 

diff --git a/mm/shmem.c b/mm/shmem.c
index 905c0e1cf5aff162a12c0c2d1a68523d7517990c..25f55a3a93b34ceb3a3425598e52b5c8798c458e 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -363,7 +363,7 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 #define SHMEM_HUGE_DENY                (-1)
 #define SHMEM_HUGE_FORCE       (-2)
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 /* ifdef here to avoid bloating shmem.o when not necessary */
 
 int shmem_huge __read_mostly;
@@ -406,11 +406,11 @@ static const char *shmem_format_huge(int huge)
        }
 }
 
-#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
+#else /* !CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 
 #define shmem_huge SHMEM_HUGE_DENY
 
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 
 /*
  * Like add_to_page_cache_locked, but error if expected item has gone.
@@ -1229,7 +1229,7 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
        void __rcu **results;
        struct page *page;
 
-       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
                return NULL;
 
        rcu_read_lock();
@@ -1270,7 +1270,7 @@ static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
        int nr;
        int err = -ENOSPC;
 
-       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
                huge = false;
        nr = huge ? HPAGE_PMD_NR : 1;
 
@@ -1773,7 +1773,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
        get_area = current->mm->get_unmapped_area;
        addr = get_area(file, uaddr, len, pgoff, flags);
 
-       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
                return addr;
        if (IS_ERR_VALUE(addr))
                return addr;
@@ -1890,7 +1890,7 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
        file_accessed(file);
        vma->vm_ops = &shmem_vm_ops;
-       if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
+       if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
                        ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
                        (vma->vm_end & HPAGE_PMD_MASK)) {
                khugepaged_enter(vma, vma->vm_flags);
@@ -3287,7 +3287,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
                        sbinfo->gid = make_kgid(current_user_ns(), gid);
                        if (!gid_valid(sbinfo->gid))
                                goto bad_val;
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
                } else if (!strcmp(this_char, "huge")) {
                        int huge;
                        huge = shmem_parse_huge(value);
@@ -3384,7 +3384,7 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
        if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
                seq_printf(seq, ",gid=%u",
                                from_kgid_munged(&init_user_ns, sbinfo->gid));
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
        /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
        if (sbinfo->huge)
                seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
@@ -3730,7 +3730,7 @@ int __init shmem_init(void)
                goto out1;
        }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
        if (has_transparent_hugepage() && shmem_huge < SHMEM_HUGE_DENY)
                SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
        else
@@ -3747,7 +3747,7 @@ out3:
        return error;
 }
 
-#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
+#if defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && defined(CONFIG_SYSFS)
 static ssize_t shmem_enabled_show(struct kobject *kobj,
                struct kobj_attribute *attr, char *buf)
 {
@@ -3830,7 +3830,7 @@ bool shmem_huge_enabled(struct vm_area_struct *vma)
                        return false;
        }
 }
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
+#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE && CONFIG_SYSFS */
 
 #else /* !CONFIG_SHMEM */
 
@@ -4010,7 +4010,7 @@ int shmem_zero_setup(struct vm_area_struct *vma)
        vma->vm_file = file;
        vma->vm_ops = &shmem_vm_ops;
 
-       if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
+       if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
                        ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
                        (vma->vm_end & HPAGE_PMD_MASK)) {
                khugepaged_enter(vma, vma->vm_flags);