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/mm/Kconfig b/mm/Kconfig
index 3e2daef..3c81803 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -440,6 +440,14 @@
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
#
config NEED_PER_CPU_KM
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2706182..d3abbf2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -287,7 +287,7 @@
&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 573e436..93d5f87 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -819,6 +819,8 @@
(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 @@
}
}
-#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 @@
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 @@
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 712790e..4425b60 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2920,7 +2920,7 @@
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 @@
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 905c0e1..25f55a3 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -363,7 +363,7 @@
#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 @@
}
}
-#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 @@
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 @@
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 @@
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 @@
{
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 @@
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 @@
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 @@
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 @@
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 @@
return false;
}
}
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
+#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE && CONFIG_SYSFS */
#else /* !CONFIG_SHMEM */
@@ -4010,7 +4010,7 @@
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);