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mm, thp: remove infrastructure for handling splitting PMDs 

With new refcounting we don't need to mark PMDs splitting.  Let's drop
code to handle this.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2016-01-15 16:53:39 -08:00 committed by Linus Torvalds
parent 1f19617d77
commit 4b471e8898
13 changed files with 41 additions and 183 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
Documentation/features/vm/pmdp_splitting_flush/arch-support.txt
View File

@ -1,40 +0,0 @@
#
# Feature name: pmdp_splitting_flush
# Kconfig: __HAVE_ARCH_PMDP_SPLITTING_FLUSH
# description: arch supports the pmdp_splitting_flush() VM API
#
-----------------------
| arch |status|
-----------------------
| alpha: | TODO |
| arc: | TODO |
| arm: | ok |
| arm64: | ok |
| avr32: | TODO |
| blackfin: | TODO |
| c6x: | TODO |
| cris: | TODO |
| frv: | TODO |
| h8300: | TODO |
| hexagon: | TODO |
| ia64: | TODO |
| m32r: | TODO |
| m68k: | TODO |
| metag: | TODO |
| microblaze: | TODO |
| mips: | ok |
| mn10300: | TODO |
| nios2: | TODO |
| openrisc: | TODO |
| parisc: | TODO |
| powerpc: | ok |
| s390: | ok |
| score: | TODO |
| sh: | TODO |
| sparc: | TODO |
| tile: | TODO |
| um: | TODO |
| unicore32: | TODO |
| x86: | ok |
| xtensa: | TODO |
-----------------------

8
fs/proc/task_mmu.c
View File

@ -602,7 +602,7 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
pte_t *pte;
spinlock_t *ptl;
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
smaps_pmd_entry(pmd, addr, walk);
spin_unlock(ptl);
return 0;
@ -913,7 +913,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
spinlock_t *ptl;
struct page *page;
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
clear_soft_dirty_pmd(vma, addr, pmd);
goto out;
@ -1187,7 +1187,7 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
int err = 0;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (pmd_trans_huge_lock(pmdp, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmdp, vma, &ptl)) {
u64 flags = 0, frame = 0;
pmd_t pmd = *pmdp;
@ -1519,7 +1519,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
pte_t *orig_pte;
pte_t *pte;
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
pte_t huge_pte = *(pte_t *)pmd;
struct page *page;

9
include/asm-generic/pgtable.h
View File

@ -207,11 +207,6 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
extern void pmdp_splitting_flush(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
#endif
#ifndef pmdp_collapse_flush
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
extern pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
@ -627,10 +622,6 @@ static inline int pmd_trans_huge(pmd_t pmd)
{
return 0;
}
static inline int pmd_trans_splitting(pmd_t pmd)
{
return 0;
}
#ifndef __HAVE_ARCH_PMD_WRITE
static inline int pmd_write(pmd_t pmd)
{

21
include/linux/huge_mm.h
View File

@ -25,7 +25,7 @@ extern int zap_huge_pmd(struct mmu_gather *tlb,
extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
unsigned char *vec);
extern int move_huge_pmd(struct vm_area_struct *vma,
extern bool move_huge_pmd(struct vm_area_struct *vma,
struct vm_area_struct *new_vma,
unsigned long old_addr,
unsigned long new_addr, unsigned long old_end,
@ -48,15 +48,9 @@ enum transparent_hugepage_flag {
#endif
};
enum page_check_address_pmd_flag {
PAGE_CHECK_ADDRESS_PMD_FLAG,
PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG,
PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG,
};
extern pmd_t *page_check_address_pmd(struct page *page,
struct mm_struct *mm,
unsigned long address,
enum page_check_address_pmd_flag flag,
spinlock_t **ptl);
#define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
@ -100,7 +94,6 @@ extern unsigned long transparent_hugepage_flags;
#define split_huge_page(page) BUILD_BUG()
#define split_huge_pmd(__vma, __pmd, __address) BUILD_BUG()
#define wait_split_huge_page(__anon_vma, __pmd) BUILD_BUG()
#if HPAGE_PMD_ORDER >= MAX_ORDER
#error "hugepages can't be allocated by the buddy allocator"
#endif
@ -110,17 +103,17 @@ extern void vma_adjust_trans_huge(struct vm_area_struct *vma,
unsigned long start,
unsigned long end,
long adjust_next);
extern int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
extern bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
spinlock_t **ptl);
/* mmap_sem must be held on entry */
static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
static inline bool pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
spinlock_t **ptl)
{
VM_BUG_ON_VMA(!rwsem_is_locked(&vma->vm_mm->mmap_sem), vma);
if (pmd_trans_huge(*pmd))
return __pmd_trans_huge_lock(pmd, vma, ptl);
else
return 0;
return false;
}
static inline int hpage_nr_pages(struct page *page)
{
@ -165,8 +158,6 @@ static inline int split_huge_page(struct page *page)
{
return 0;
}
#define wait_split_huge_page(__anon_vma, __pmd) \
do { } while (0)
#define split_huge_pmd(__vma, __pmd, __address) \
do { } while (0)
static inline int hugepage_madvise(struct vm_area_struct *vma,
@ -181,10 +172,10 @@ static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
long adjust_next)
{
}
static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
static inline bool pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
spinlock_t **ptl)
{
return 0;
return false;
}
static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,

12
mm/gup.c
View File

@ -241,13 +241,6 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
spin_unlock(ptl);
return follow_page_pte(vma, address, pmd, flags);
}
if (unlikely(pmd_trans_splitting(*pmd))) {
spin_unlock(ptl);
wait_split_huge_page(vma->anon_vma, pmd);
return follow_page_pte(vma, address, pmd, flags);
}
if (flags & FOLL_SPLIT) {
int ret;
page = pmd_page(*pmd);
@ -1068,9 +1061,6 @@ struct page *get_dump_page(unsigned long addr)
* *) HAVE_RCU_TABLE_FREE is enabled, and tlb_remove_table is used to free
* pages containing page tables.
*
* *) THP splits will broadcast an IPI, this can be achieved by overriding
* pmdp_splitting_flush.
*
* *) ptes can be read atomically by the architecture.
*
* *) access_ok is sufficient to validate userspace address ranges.
@ -1267,7 +1257,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
pmd_t pmd = READ_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
if (pmd_none(pmd) || pmd_trans_splitting(pmd))
if (pmd_none(pmd))
return 0;
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd))) {

67
mm/huge_memory.c
View File

@ -986,15 +986,6 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
goto out_unlock;
}
if (unlikely(pmd_trans_splitting(pmd))) {
/* split huge page running from under us */
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
pte_free(dst_mm, pgtable);
wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
goto out;
}
src_page = pmd_page(pmd);
VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
get_page(src_page);
@ -1470,7 +1461,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
pmd_t orig_pmd;
spinlock_t *ptl;
if (__pmd_trans_huge_lock(pmd, vma, &ptl) != 1)
if (!__pmd_trans_huge_lock(pmd, vma, &ptl))
return 0;
/*
* For architectures like ppc64 we look at deposited pgtable
@ -1504,13 +1495,12 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
return 1;
}
int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
unsigned long old_addr,
unsigned long new_addr, unsigned long old_end,
pmd_t *old_pmd, pmd_t *new_pmd)
{
spinlock_t *old_ptl, *new_ptl;
int ret = 0;
pmd_t pmd;
struct mm_struct *mm = vma->vm_mm;
@ -1519,7 +1509,7 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
(new_addr & ~HPAGE_PMD_MASK) ||
old_end - old_addr < HPAGE_PMD_SIZE ||
(new_vma->vm_flags & VM_NOHUGEPAGE))
goto out;
return false;
/*
* The destination pmd shouldn't be established, free_pgtables()
@ -1527,15 +1517,14 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
*/
if (WARN_ON(!pmd_none(*new_pmd))) {
VM_BUG_ON(pmd_trans_huge(*new_pmd));
goto out;
return false;
}
/*
* We don't have to worry about the ordering of src and dst
* ptlocks because exclusive mmap_sem prevents deadlock.
*/
ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
if (ret == 1) {
if (__pmd_trans_huge_lock(old_pmd, vma, &old_ptl)) {
new_ptl = pmd_lockptr(mm, new_pmd);
if (new_ptl != old_ptl)
spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
@ -1551,9 +1540,9 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
if (new_ptl != old_ptl)
spin_unlock(new_ptl);
spin_unlock(old_ptl);
return true;
}
out:
return ret;
return false;
}
/*
@ -1569,7 +1558,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
spinlock_t *ptl;
int ret = 0;
if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (__pmd_trans_huge_lock(pmd, vma, &ptl)) {
pmd_t entry;
bool preserve_write = prot_numa && pmd_write(*pmd);
ret = 1;
@ -1600,29 +1589,19 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
}
/*
* Returns 1 if a given pmd maps a stable (not under splitting) thp.
* Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
* Returns true if a given pmd maps a thp, false otherwise.
*
* Note that if it returns 1, this routine returns without unlocking page
* table locks. So callers must unlock them.
* Note that if it returns true, this routine returns without unlocking page
* table lock. So callers must unlock it.
*/
int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
spinlock_t **ptl)
{
*ptl = pmd_lock(vma->vm_mm, pmd);
if (likely(pmd_trans_huge(*pmd))) {
if (unlikely(pmd_trans_splitting(*pmd))) {
spin_unlock(*ptl);
wait_split_huge_page(vma->anon_vma, pmd);
return -1;
} else {
/* Thp mapped by 'pmd' is stable, so we can
* handle it as it is. */
return 1;
}
}
if (likely(pmd_trans_huge(*pmd)))
return true;
spin_unlock(*ptl);
return 0;
return false;
}
/*
@ -1636,7 +1615,6 @@ int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
pmd_t *page_check_address_pmd(struct page *page,
struct mm_struct *mm,
unsigned long address,
enum page_check_address_pmd_flag flag,
spinlock_t **ptl)
{
pgd_t *pgd;
@ -1659,21 +1637,8 @@ pmd_t *page_check_address_pmd(struct page *page,
goto unlock;
if (pmd_page(*pmd) != page)
goto unlock;
/*
* split_vma() may create temporary aliased mappings. There is
* no risk as long as all huge pmd are found and have their
* splitting bit set before __split_huge_page_refcount
* runs. Finding the same huge pmd more than once during the
* same rmap walk is not a problem.
*/
if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
pmd_trans_splitting(*pmd))
goto unlock;
if (pmd_trans_huge(*pmd)) {
VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
!pmd_trans_splitting(*pmd));
if (pmd_trans_huge(*pmd))
return pmd;
}
unlock:
spin_unlock(*ptl);
return NULL;

13
mm/memcontrol.c
View File

@ -4675,7 +4675,7 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
pte_t *pte;
spinlock_t *ptl;
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
mc.precharge += HPAGE_PMD_NR;
spin_unlock(ptl);
@ -4863,16 +4863,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
union mc_target target;
struct page *page;
/*
* No race with splitting thp happens because:
* - if pmd_trans_huge_lock() returns 1, the relevant thp is not
* under splitting, which means there's no concurrent thp split,
* - if another thread runs into split_huge_page() just after we
* entered this if-block, the thread must wait for page table lock
* to be unlocked in __split_huge_page_splitting(), where the main
* part of thp split is not executed yet.
*/
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
if (mc.precharge < HPAGE_PMD_NR) {
spin_unlock(ptl);
return 0;

18
mm/memory.c
View File

@ -566,7 +566,6 @@ int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
{
spinlock_t *ptl;
pgtable_t new = pte_alloc_one(mm, address);
int wait_split_huge_page;
if (!new)
return -ENOMEM;
@ -586,18 +585,14 @@ int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
ptl = pmd_lock(mm, pmd);
wait_split_huge_page = 0;
if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
atomic_long_inc(&mm->nr_ptes);
pmd_populate(mm, pmd, new);
new = NULL;
} else if (unlikely(pmd_trans_splitting(*pmd)))
wait_split_huge_page = 1;
}
spin_unlock(ptl);
if (new)
pte_free(mm, new);
if (wait_split_huge_page)
wait_split_huge_page(vma->anon_vma, pmd);
return 0;
}
@ -613,8 +608,7 @@ int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
pmd_populate_kernel(&init_mm, pmd, new);
new = NULL;
} else
VM_BUG_ON(pmd_trans_splitting(*pmd));
}
spin_unlock(&init_mm.page_table_lock);
if (new)
pte_free_kernel(&init_mm, new);
@ -3374,14 +3368,6 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (pmd_trans_huge(orig_pmd)) {
unsigned int dirty = flags & FAULT_FLAG_WRITE;
/*
* If the pmd is splitting, return and retry the
* the fault. Alternative: wait until the split
* is done, and goto retry.
*/
if (pmd_trans_splitting(orig_pmd))
return 0;
if (pmd_protnone(orig_pmd))
return do_huge_pmd_numa_page(mm, vma, address,
orig_pmd, pmd);

2
mm/mincore.c
View File

@ -117,7 +117,7 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
unsigned char *vec = walk->private;
int nr = (end - addr) >> PAGE_SHIFT;
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
memset(vec, 1, nr);
spin_unlock(ptl);
goto out;

15
mm/mremap.c
View File

@ -192,25 +192,24 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
if (!new_pmd)
break;
if (pmd_trans_huge(*old_pmd)) {
int err = 0;
if (extent == HPAGE_PMD_SIZE) {
bool moved;
VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma,
vma);
/* See comment in move_ptes() */
if (need_rmap_locks)
anon_vma_lock_write(vma->anon_vma);
err = move_huge_pmd(vma, new_vma, old_addr,
moved = move_huge_pmd(vma, new_vma, old_addr,
new_addr, old_end,
old_pmd, new_pmd);
if (need_rmap_locks)
anon_vma_unlock_write(vma->anon_vma);
if (moved) {
need_flush = true;
continue;
}
}
if (err > 0) {
need_flush = true;
continue;
} else if (!err) {
split_huge_pmd(vma, old_pmd, old_addr);
}
split_huge_pmd(vma, old_pmd, old_addr);
VM_BUG_ON(pmd_trans_huge(*old_pmd));
}
if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,

3
mm/page_idle.c
View File

@ -61,8 +61,7 @@ static int page_idle_clear_pte_refs_one(struct page *page,
bool referenced = false;
if (unlikely(PageTransHuge(page))) {
pmd = page_check_address_pmd(page, mm, addr,
PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
pmd = page_check_address_pmd(page, mm, addr, &ptl);
if (pmd) {
referenced = pmdp_clear_young_notify(vma, addr, pmd);
spin_unlock(ptl);

12
mm/pgtable-generic.c
View File

@ -139,18 +139,6 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
}
#endif
#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{
pmd_t pmd = pmd_mksplitting(*pmdp);
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
set_pmd_at(vma->vm_mm, address, pmdp, pmd);
/* tlb flush only to serialize against gup-fast */
flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
}
#endif
#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable)

4
mm/rmap.c
View File

@ -843,8 +843,7 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
* rmap might return false positives; we must filter
* these out using page_check_address_pmd().
*/
pmd = page_check_address_pmd(page, mm, address,
PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
pmd = page_check_address_pmd(page, mm, address, &ptl);
if (!pmd)
return SWAP_AGAIN;
@ -854,7 +853,6 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
return SWAP_FAIL; /* To break the loop */
}
/* go ahead even if the pmd is pmd_trans_splitting() */
if (pmdp_clear_flush_young_notify(vma, address, pmd))
referenced++;
spin_unlock(ptl);