#include <asm/pgalloc.h>
#include "internal.h"
+enum scan_result {
+ SCAN_FAIL,
+ SCAN_SUCCEED,
+ SCAN_PMD_NULL,
+ SCAN_EXCEED_NONE_PTE,
+ SCAN_PTE_NON_PRESENT,
+ SCAN_PAGE_RO,
+ SCAN_NO_REFERENCED_PAGE,
+ SCAN_PAGE_NULL,
+ SCAN_SCAN_ABORT,
+ SCAN_PAGE_COUNT,
+ SCAN_PAGE_LRU,
+ SCAN_PAGE_LOCK,
+ SCAN_PAGE_ANON,
+ SCAN_PAGE_COMPOUND,
+ SCAN_ANY_PROCESS,
+ SCAN_VMA_NULL,
+ SCAN_VMA_CHECK,
+ SCAN_ADDRESS_RANGE,
+ SCAN_SWAP_CACHE_PAGE,
+ SCAN_DEL_PAGE_LRU,
+ SCAN_ALLOC_HUGE_PAGE_FAIL,
+ SCAN_CGROUP_CHARGE_FAIL
+};
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/huge_memory.h>
+
/*
* By default transparent hugepage support is disabled in order that avoid
* to risk increase the memory footprint of applications without a guaranteed
VM_BUG_ON_PAGE(!PageCompound(page), page);
- if (mem_cgroup_try_charge(page, mm, gfp, &memcg)) {
+ if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) {
put_page(page);
count_vm_event(THP_FAULT_FALLBACK);
return VM_FAULT_FALLBACK;
pgtable = pte_alloc_one(mm, haddr);
if (unlikely(!pgtable)) {
- mem_cgroup_cancel_charge(page, memcg);
+ mem_cgroup_cancel_charge(page, memcg, true);
put_page(page);
return VM_FAULT_OOM;
}
ptl = pmd_lock(mm, pmd);
if (unlikely(!pmd_none(*pmd))) {
spin_unlock(ptl);
- mem_cgroup_cancel_charge(page, memcg);
+ mem_cgroup_cancel_charge(page, memcg, true);
put_page(page);
pte_free(mm, pgtable);
} else {
int ret;
spin_unlock(ptl);
- mem_cgroup_cancel_charge(page, memcg);
+ mem_cgroup_cancel_charge(page, memcg, true);
put_page(page);
pte_free(mm, pgtable);
ret = handle_userfault(vma, address, flags,
entry = mk_huge_pmd(page, vma->vm_page_prot);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
- page_add_new_anon_rmap(page, vma, haddr);
- mem_cgroup_commit_charge(page, memcg, false);
+ page_add_new_anon_rmap(page, vma, haddr, true);
+ mem_cgroup_commit_charge(page, memcg, false, true);
lru_cache_add_active_or_unevictable(page, vma);
pgtable_trans_huge_deposit(mm, pmd, pgtable);
set_pmd_at(mm, haddr, pmd, entry);
if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
return VM_FAULT_FALLBACK;
+ if (vma->vm_flags & VM_LOCKED)
+ return VM_FAULT_FALLBACK;
if (unlikely(anon_vma_prepare(vma)))
return VM_FAULT_OOM;
if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
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);
- page_dup_rmap(src_page);
+ page_dup_rmap(src_page, true);
add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
pmdp_set_wrprotect(src_mm, addr, src_pmd);
spin_unlock(ptl);
}
-/*
- * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
- * during copy_user_huge_page()'s copy_page_rep(): in the case when
- * the source page gets split and a tail freed before copy completes.
- * Called under pmd_lock of checked pmd, so safe from splitting itself.
- */
-static void get_user_huge_page(struct page *page)
-{
- if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
- struct page *endpage = page + HPAGE_PMD_NR;
-
- atomic_add(HPAGE_PMD_NR, &page->_count);
- while (++page < endpage)
- get_huge_page_tail(page);
- } else {
- get_page(page);
- }
-}
-
-static void put_user_huge_page(struct page *page)
-{
- if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
- struct page *endpage = page + HPAGE_PMD_NR;
-
- while (page < endpage)
- put_page(page++);
- } else {
- put_page(page);
- }
-}
-
static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long address,
vma, address, page_to_nid(page));
if (unlikely(!pages[i] ||
mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
- &memcg))) {
+ &memcg, false))) {
if (pages[i])
put_page(pages[i]);
while (--i >= 0) {
memcg = (void *)page_private(pages[i]);
set_page_private(pages[i], 0);
- mem_cgroup_cancel_charge(pages[i], memcg);
+ mem_cgroup_cancel_charge(pages[i], memcg,
+ false);
put_page(pages[i]);
}
kfree(pages);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
memcg = (void *)page_private(pages[i]);
set_page_private(pages[i], 0);
- page_add_new_anon_rmap(pages[i], vma, haddr);
- mem_cgroup_commit_charge(pages[i], memcg, false);
+ page_add_new_anon_rmap(pages[i], vma, haddr, false);
+ mem_cgroup_commit_charge(pages[i], memcg, false, false);
lru_cache_add_active_or_unevictable(pages[i], vma);
pte = pte_offset_map(&_pmd, haddr);
VM_BUG_ON(!pte_none(*pte));
smp_wmb(); /* make pte visible before pmd */
pmd_populate(mm, pmd, pgtable);
- page_remove_rmap(page);
+ page_remove_rmap(page, true);
spin_unlock(ptl);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
for (i = 0; i < HPAGE_PMD_NR; i++) {
memcg = (void *)page_private(pages[i]);
set_page_private(pages[i], 0);
- mem_cgroup_cancel_charge(pages[i], memcg);
+ mem_cgroup_cancel_charge(pages[i], memcg, false);
put_page(pages[i]);
}
kfree(pages);
page = pmd_page(orig_pmd);
VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
- if (page_mapcount(page) == 1) {
+ /*
+ * We can only reuse the page if nobody else maps the huge page or it's
+ * part. We can do it by checking page_mapcount() on each sub-page, but
+ * it's expensive.
+ * The cheaper way is to check page_count() to be equal 1: every
+ * mapcount takes page reference reference, so this way we can
+ * guarantee, that the PMD is the only mapping.
+ * This can give false negative if somebody pinned the page, but that's
+ * fine.
+ */
+ if (page_mapcount(page) == 1 && page_count(page) == 1) {
pmd_t entry;
entry = pmd_mkyoung(orig_pmd);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
ret |= VM_FAULT_WRITE;
goto out_unlock;
}
- get_user_huge_page(page);
+ get_page(page);
spin_unlock(ptl);
alloc:
if (transparent_hugepage_enabled(vma) &&
if (unlikely(!new_page)) {
if (!page) {
- split_huge_page_pmd(vma, address, pmd);
+ split_huge_pmd(vma, pmd, address);
ret |= VM_FAULT_FALLBACK;
} else {
ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
pmd, orig_pmd, page, haddr);
if (ret & VM_FAULT_OOM) {
- split_huge_page(page);
+ split_huge_pmd(vma, pmd, address);
ret |= VM_FAULT_FALLBACK;
}
- put_user_huge_page(page);
+ put_page(page);
}
count_vm_event(THP_FAULT_FALLBACK);
goto out;
}
- if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) {
+ if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg,
+ true))) {
put_page(new_page);
if (page) {
- split_huge_page(page);
- put_user_huge_page(page);
+ split_huge_pmd(vma, pmd, address);
+ put_page(page);
} else
- split_huge_page_pmd(vma, address, pmd);
+ split_huge_pmd(vma, pmd, address);
ret |= VM_FAULT_FALLBACK;
count_vm_event(THP_FAULT_FALLBACK);
goto out;
spin_lock(ptl);
if (page)
- put_user_huge_page(page);
+ put_page(page);
if (unlikely(!pmd_same(*pmd, orig_pmd))) {
spin_unlock(ptl);
- mem_cgroup_cancel_charge(new_page, memcg);
+ mem_cgroup_cancel_charge(new_page, memcg, true);
put_page(new_page);
goto out_mn;
} else {
entry = mk_huge_pmd(new_page, vma->vm_page_prot);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
pmdp_huge_clear_flush_notify(vma, haddr, pmd);
- page_add_new_anon_rmap(new_page, vma, haddr);
- mem_cgroup_commit_charge(new_page, memcg, false);
+ page_add_new_anon_rmap(new_page, vma, haddr, true);
+ mem_cgroup_commit_charge(new_page, memcg, false, true);
lru_cache_add_active_or_unevictable(new_page, vma);
set_pmd_at(mm, haddr, pmd, entry);
update_mmu_cache_pmd(vma, address, pmd);
put_huge_zero_page();
} else {
VM_BUG_ON_PAGE(!PageHead(page), page);
- page_remove_rmap(page);
+ page_remove_rmap(page, true);
put_page(page);
}
ret |= VM_FAULT_WRITE;
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
VM_BUG_ON_PAGE(!PageCompound(page), page);
if (flags & FOLL_GET)
- get_page_foll(page);
+ get_page(page);
out:
return page;
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
put_huge_zero_page();
} else {
struct page *page = pmd_page(orig_pmd);
- page_remove_rmap(page);
+ page_remove_rmap(page, true);
VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
VM_BUG_ON_PAGE(!PageHead(page), page);
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;
(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()
*/
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);
if (new_ptl != old_ptl)
spin_unlock(new_ptl);
spin_unlock(old_ptl);
+ return true;
}
-out:
- return ret;
+ return false;
}
/*
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;
}
/*
- * 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;
}
/*
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;
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;
}
-static int __split_huge_page_splitting(struct page *page,
- struct vm_area_struct *vma,
- unsigned long address)
-{
- struct mm_struct *mm = vma->vm_mm;
- spinlock_t *ptl;
- pmd_t *pmd;
- int ret = 0;
- /* For mmu_notifiers */
- const unsigned long mmun_start = address;
- const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
-
- mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
- pmd = page_check_address_pmd(page, mm, address,
- PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
- if (pmd) {
- /*
- * We can't temporarily set the pmd to null in order
- * to split it, the pmd must remain marked huge at all
- * times or the VM won't take the pmd_trans_huge paths
- * and it won't wait on the anon_vma->root->rwsem to
- * serialize against split_huge_page*.
- */
- pmdp_splitting_flush(vma, address, pmd);
-
- ret = 1;
- spin_unlock(ptl);
- }
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
-
- return ret;
-}
-
-static void __split_huge_page_refcount(struct page *page,
- struct list_head *list)
-{
- int i;
- struct zone *zone = page_zone(page);
- struct lruvec *lruvec;
- int tail_count = 0;
-
- /* prevent PageLRU to go away from under us, and freeze lru stats */
- spin_lock_irq(&zone->lru_lock);
- lruvec = mem_cgroup_page_lruvec(page, zone);
-
- compound_lock(page);
- /* complete memcg works before add pages to LRU */
- mem_cgroup_split_huge_fixup(page);
-
- for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
- struct page *page_tail = page + i;
-
- /* tail_page->_mapcount cannot change */
- BUG_ON(page_mapcount(page_tail) < 0);
- tail_count += page_mapcount(page_tail);
- /* check for overflow */
- BUG_ON(tail_count < 0);
- BUG_ON(atomic_read(&page_tail->_count) != 0);
- /*
- * tail_page->_count is zero and not changing from
- * under us. But get_page_unless_zero() may be running
- * from under us on the tail_page. If we used
- * atomic_set() below instead of atomic_add(), we
- * would then run atomic_set() concurrently with
- * get_page_unless_zero(), and atomic_set() is
- * implemented in C not using locked ops. spin_unlock
- * on x86 sometime uses locked ops because of PPro
- * errata 66, 92, so unless somebody can guarantee
- * atomic_set() here would be safe on all archs (and
- * not only on x86), it's safer to use atomic_add().
- */
- atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
- &page_tail->_count);
-
- /* after clearing PageTail the gup refcount can be released */
- smp_mb__after_atomic();
-
- page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
- page_tail->flags |= (page->flags &
- ((1L << PG_referenced) |
- (1L << PG_swapbacked) |
- (1L << PG_mlocked) |
- (1L << PG_uptodate) |
- (1L << PG_active) |
- (1L << PG_unevictable)));
- page_tail->flags |= (1L << PG_dirty);
-
- clear_compound_head(page_tail);
-
- if (page_is_young(page))
- set_page_young(page_tail);
- if (page_is_idle(page))
- set_page_idle(page_tail);
-
- /*
- * __split_huge_page_splitting() already set the
- * splitting bit in all pmd that could map this
- * hugepage, that will ensure no CPU can alter the
- * mapcount on the head page. The mapcount is only
- * accounted in the head page and it has to be
- * transferred to all tail pages in the below code. So
- * for this code to be safe, the split the mapcount
- * can't change. But that doesn't mean userland can't
- * keep changing and reading the page contents while
- * we transfer the mapcount, so the pmd splitting
- * status is achieved setting a reserved bit in the
- * pmd, not by clearing the present bit.
- */
- page_tail->_mapcount = page->_mapcount;
-
- BUG_ON(page_tail->mapping);
- page_tail->mapping = page->mapping;
-
- page_tail->index = page->index + i;
- page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
-
- BUG_ON(!PageAnon(page_tail));
- BUG_ON(!PageUptodate(page_tail));
- BUG_ON(!PageDirty(page_tail));
- BUG_ON(!PageSwapBacked(page_tail));
-
- lru_add_page_tail(page, page_tail, lruvec, list);
- }
- atomic_sub(tail_count, &page->_count);
- BUG_ON(atomic_read(&page->_count) <= 0);
-
- __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
-
- ClearPageCompound(page);
- compound_unlock(page);
- spin_unlock_irq(&zone->lru_lock);
-
- for (i = 1; i < HPAGE_PMD_NR; i++) {
- struct page *page_tail = page + i;
- BUG_ON(page_count(page_tail) <= 0);
- /*
- * Tail pages may be freed if there wasn't any mapping
- * like if add_to_swap() is running on a lru page that
- * had its mapping zapped. And freeing these pages
- * requires taking the lru_lock so we do the put_page
- * of the tail pages after the split is complete.
- */
- put_page(page_tail);
- }
-
- /*
- * Only the head page (now become a regular page) is required
- * to be pinned by the caller.
- */
- BUG_ON(page_count(page) <= 0);
-}
-
-static int __split_huge_page_map(struct page *page,
- struct vm_area_struct *vma,
- unsigned long address)
-{
- struct mm_struct *mm = vma->vm_mm;
- spinlock_t *ptl;
- pmd_t *pmd, _pmd;
- int ret = 0, i;
- pgtable_t pgtable;
- unsigned long haddr;
-
- pmd = page_check_address_pmd(page, mm, address,
- PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
- if (pmd) {
- pgtable = pgtable_trans_huge_withdraw(mm, pmd);
- pmd_populate(mm, &_pmd, pgtable);
- if (pmd_write(*pmd))
- BUG_ON(page_mapcount(page) != 1);
-
- haddr = address;
- for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
- pte_t *pte, entry;
- BUG_ON(PageCompound(page+i));
- /*
- * Note that NUMA hinting access restrictions are not
- * transferred to avoid any possibility of altering
- * permissions across VMAs.
- */
- entry = mk_pte(page + i, vma->vm_page_prot);
- entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- if (!pmd_write(*pmd))
- entry = pte_wrprotect(entry);
- if (!pmd_young(*pmd))
- entry = pte_mkold(entry);
- pte = pte_offset_map(&_pmd, haddr);
- BUG_ON(!pte_none(*pte));
- set_pte_at(mm, haddr, pte, entry);
- pte_unmap(pte);
- }
-
- smp_wmb(); /* make pte visible before pmd */
- /*
- * Up to this point the pmd is present and huge and
- * userland has the whole access to the hugepage
- * during the split (which happens in place). If we
- * overwrite the pmd with the not-huge version
- * pointing to the pte here (which of course we could
- * if all CPUs were bug free), userland could trigger
- * a small page size TLB miss on the small sized TLB
- * while the hugepage TLB entry is still established
- * in the huge TLB. Some CPU doesn't like that. See
- * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
- * Erratum 383 on page 93. Intel should be safe but is
- * also warns that it's only safe if the permission
- * and cache attributes of the two entries loaded in
- * the two TLB is identical (which should be the case
- * here). But it is generally safer to never allow
- * small and huge TLB entries for the same virtual
- * address to be loaded simultaneously. So instead of
- * doing "pmd_populate(); flush_pmd_tlb_range();" we first
- * mark the current pmd notpresent (atomically because
- * here the pmd_trans_huge and pmd_trans_splitting
- * must remain set at all times on the pmd until the
- * split is complete for this pmd), then we flush the
- * SMP TLB and finally we write the non-huge version
- * of the pmd entry with pmd_populate.
- */
- pmdp_invalidate(vma, address, pmd);
- pmd_populate(mm, pmd, pgtable);
- ret = 1;
- spin_unlock(ptl);
- }
-
- return ret;
-}
-
-/* must be called with anon_vma->root->rwsem held */
-static void __split_huge_page(struct page *page,
- struct anon_vma *anon_vma,
- struct list_head *list)
-{
- int mapcount, mapcount2;
- pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- struct anon_vma_chain *avc;
-
- BUG_ON(!PageHead(page));
- BUG_ON(PageTail(page));
-
- mapcount = 0;
- anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
- struct vm_area_struct *vma = avc->vma;
- unsigned long addr = vma_address(page, vma);
- BUG_ON(is_vma_temporary_stack(vma));
- mapcount += __split_huge_page_splitting(page, vma, addr);
- }
- /*
- * It is critical that new vmas are added to the tail of the
- * anon_vma list. This guarantes that if copy_huge_pmd() runs
- * and establishes a child pmd before
- * __split_huge_page_splitting() freezes the parent pmd (so if
- * we fail to prevent copy_huge_pmd() from running until the
- * whole __split_huge_page() is complete), we will still see
- * the newly established pmd of the child later during the
- * walk, to be able to set it as pmd_trans_splitting too.
- */
- if (mapcount != page_mapcount(page)) {
- pr_err("mapcount %d page_mapcount %d\n",
- mapcount, page_mapcount(page));
- BUG();
- }
-
- __split_huge_page_refcount(page, list);
-
- mapcount2 = 0;
- anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
- struct vm_area_struct *vma = avc->vma;
- unsigned long addr = vma_address(page, vma);
- BUG_ON(is_vma_temporary_stack(vma));
- mapcount2 += __split_huge_page_map(page, vma, addr);
- }
- if (mapcount != mapcount2) {
- pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
- mapcount, mapcount2, page_mapcount(page));
- BUG();
- }
-}
-
-/*
- * Split a hugepage into normal pages. This doesn't change the position of head
- * page. If @list is null, tail pages will be added to LRU list, otherwise, to
- * @list. Both head page and tail pages will inherit mapping, flags, and so on
- * from the hugepage.
- * Return 0 if the hugepage is split successfully otherwise return 1.
- */
-int split_huge_page_to_list(struct page *page, struct list_head *list)
-{
- struct anon_vma *anon_vma;
- int ret = 1;
-
- BUG_ON(is_huge_zero_page(page));
- BUG_ON(!PageAnon(page));
-
- /*
- * The caller does not necessarily hold an mmap_sem that would prevent
- * the anon_vma disappearing so we first we take a reference to it
- * and then lock the anon_vma for write. This is similar to
- * page_lock_anon_vma_read except the write lock is taken to serialise
- * against parallel split or collapse operations.
- */
- anon_vma = page_get_anon_vma(page);
- if (!anon_vma)
- goto out;
- anon_vma_lock_write(anon_vma);
-
- ret = 0;
- if (!PageCompound(page))
- goto out_unlock;
-
- BUG_ON(!PageSwapBacked(page));
- __split_huge_page(page, anon_vma, list);
- count_vm_event(THP_SPLIT);
-
- BUG_ON(PageCompound(page));
-out_unlock:
- anon_vma_unlock_write(anon_vma);
- put_anon_vma(anon_vma);
-out:
- return ret;
-}
-
#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
int hugepage_madvise(struct vm_area_struct *vma,
unsigned long address,
pte_t *pte)
{
- struct page *page;
+ struct page *page = NULL;
pte_t *_pte;
- int none_or_zero = 0;
+ int none_or_zero = 0, result = 0;
bool referenced = false, writable = false;
+
for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
_pte++, address += PAGE_SIZE) {
pte_t pteval = *_pte;
if (pte_none(pteval) || (pte_present(pteval) &&
is_zero_pfn(pte_pfn(pteval)))) {
if (!userfaultfd_armed(vma) &&
- ++none_or_zero <= khugepaged_max_ptes_none)
+ ++none_or_zero <= khugepaged_max_ptes_none) {
continue;
- else
+ } else {
+ result = SCAN_EXCEED_NONE_PTE;
goto out;
+ }
}
- if (!pte_present(pteval))
+ if (!pte_present(pteval)) {
+ result = SCAN_PTE_NON_PRESENT;
goto out;
+ }
page = vm_normal_page(vma, address, pteval);
- if (unlikely(!page))
+ if (unlikely(!page)) {
+ result = SCAN_PAGE_NULL;
goto out;
+ }
VM_BUG_ON_PAGE(PageCompound(page), page);
VM_BUG_ON_PAGE(!PageAnon(page), page);
* is needed to serialize against split_huge_page
* when invoked from the VM.
*/
- if (!trylock_page(page))
+ if (!trylock_page(page)) {
+ result = SCAN_PAGE_LOCK;
goto out;
+ }
/*
* cannot use mapcount: can't collapse if there's a gup pin.
*/
if (page_count(page) != 1 + !!PageSwapCache(page)) {
unlock_page(page);
+ result = SCAN_PAGE_COUNT;
goto out;
}
if (pte_write(pteval)) {
} else {
if (PageSwapCache(page) && !reuse_swap_page(page)) {
unlock_page(page);
+ result = SCAN_SWAP_CACHE_PAGE;
goto out;
}
/*
*/
if (isolate_lru_page(page)) {
unlock_page(page);
+ result = SCAN_DEL_PAGE_LRU;
goto out;
}
/* 0 stands for page_is_file_cache(page) == false */
mmu_notifier_test_young(vma->vm_mm, address))
referenced = true;
}
- if (likely(referenced && writable))
- return 1;
+ if (likely(writable)) {
+ if (likely(referenced)) {
+ result = SCAN_SUCCEED;
+ trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero,
+ referenced, writable, result);
+ return 1;
+ }
+ } else {
+ result = SCAN_PAGE_RO;
+ }
+
out:
release_pte_pages(pte, _pte);
+ trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero,
+ referenced, writable, result);
return 0;
}
* superfluous.
*/
pte_clear(vma->vm_mm, address, _pte);
- page_remove_rmap(src_page);
+ page_remove_rmap(src_page, false);
spin_unlock(ptl);
free_page_and_swap_cache(src_page);
}
if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
(vma->vm_flags & VM_NOHUGEPAGE))
return false;
-
+ if (vma->vm_flags & VM_LOCKED)
+ return false;
if (!vma->anon_vma || vma->vm_ops)
return false;
if (is_vma_temporary_stack(vma))
pgtable_t pgtable;
struct page *new_page;
spinlock_t *pmd_ptl, *pte_ptl;
- int isolated;
+ int isolated, result = 0;
unsigned long hstart, hend;
struct mem_cgroup *memcg;
unsigned long mmun_start; /* For mmu_notifiers */
/* release the mmap_sem read lock. */
new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
- if (!new_page)
- return;
+ if (!new_page) {
+ result = SCAN_ALLOC_HUGE_PAGE_FAIL;
+ goto out_nolock;
+ }
- if (unlikely(mem_cgroup_try_charge(new_page, mm,
- gfp, &memcg)))
- return;
+ if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
+ result = SCAN_CGROUP_CHARGE_FAIL;
+ goto out_nolock;
+ }
/*
* Prevent all access to pagetables with the exception of
* handled by the anon_vma lock + PG_lock.
*/
down_write(&mm->mmap_sem);
- if (unlikely(khugepaged_test_exit(mm)))
+ if (unlikely(khugepaged_test_exit(mm))) {
+ result = SCAN_ANY_PROCESS;
goto out;
+ }
vma = find_vma(mm, address);
- if (!vma)
+ if (!vma) {
+ result = SCAN_VMA_NULL;
goto out;
+ }
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
- if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+ if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
+ result = SCAN_ADDRESS_RANGE;
goto out;
- if (!hugepage_vma_check(vma))
+ }
+ if (!hugepage_vma_check(vma)) {
+ result = SCAN_VMA_CHECK;
goto out;
+ }
pmd = mm_find_pmd(mm, address);
- if (!pmd)
+ if (!pmd) {
+ result = SCAN_PMD_NULL;
goto out;
+ }
anon_vma_lock_write(vma->anon_vma);
pmd_populate(mm, pmd, pmd_pgtable(_pmd));
spin_unlock(pmd_ptl);
anon_vma_unlock_write(vma->anon_vma);
+ result = SCAN_FAIL;
goto out;
}
spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
- page_add_new_anon_rmap(new_page, vma, address);
- mem_cgroup_commit_charge(new_page, memcg, false);
+ page_add_new_anon_rmap(new_page, vma, address, true);
+ mem_cgroup_commit_charge(new_page, memcg, false, true);
lru_cache_add_active_or_unevictable(new_page, vma);
pgtable_trans_huge_deposit(mm, pmd, pgtable);
set_pmd_at(mm, address, pmd, _pmd);
*hpage = NULL;
khugepaged_pages_collapsed++;
+ result = SCAN_SUCCEED;
out_up_write:
up_write(&mm->mmap_sem);
+ trace_mm_collapse_huge_page(mm, isolated, result);
return;
+out_nolock:
+ trace_mm_collapse_huge_page(mm, isolated, result);
+ return;
out:
- mem_cgroup_cancel_charge(new_page, memcg);
+ mem_cgroup_cancel_charge(new_page, memcg, true);
goto out_up_write;
}
{
pmd_t *pmd;
pte_t *pte, *_pte;
- int ret = 0, none_or_zero = 0;
- struct page *page;
+ int ret = 0, none_or_zero = 0, result = 0;
+ struct page *page = NULL;
unsigned long _address;
spinlock_t *ptl;
int node = NUMA_NO_NODE;
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
pmd = mm_find_pmd(mm, address);
- if (!pmd)
+ if (!pmd) {
+ result = SCAN_PMD_NULL;
goto out;
+ }
memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
pte_t pteval = *_pte;
if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
if (!userfaultfd_armed(vma) &&
- ++none_or_zero <= khugepaged_max_ptes_none)
+ ++none_or_zero <= khugepaged_max_ptes_none) {
continue;
- else
+ } else {
+ result = SCAN_EXCEED_NONE_PTE;
goto out_unmap;
+ }
}
- if (!pte_present(pteval))
+ if (!pte_present(pteval)) {
+ result = SCAN_PTE_NON_PRESENT;
goto out_unmap;
+ }
if (pte_write(pteval))
writable = true;
page = vm_normal_page(vma, _address, pteval);
- if (unlikely(!page))
+ if (unlikely(!page)) {
+ result = SCAN_PAGE_NULL;
+ goto out_unmap;
+ }
+
+ /* TODO: teach khugepaged to collapse THP mapped with pte */
+ if (PageCompound(page)) {
+ result = SCAN_PAGE_COMPOUND;
goto out_unmap;
+ }
+
/*
* Record which node the original page is from and save this
* information to khugepaged_node_load[].
* hit record.
*/
node = page_to_nid(page);
- if (khugepaged_scan_abort(node))
+ if (khugepaged_scan_abort(node)) {
+ result = SCAN_SCAN_ABORT;
goto out_unmap;
+ }
khugepaged_node_load[node]++;
- VM_BUG_ON_PAGE(PageCompound(page), page);
- if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
+ if (!PageLRU(page)) {
+ result = SCAN_SCAN_ABORT;
+ goto out_unmap;
+ }
+ if (PageLocked(page)) {
+ result = SCAN_PAGE_LOCK;
goto out_unmap;
+ }
+ if (!PageAnon(page)) {
+ result = SCAN_PAGE_ANON;
+ goto out_unmap;
+ }
+
/*
* cannot use mapcount: can't collapse if there's a gup pin.
* The page must only be referenced by the scanned process
* and page swap cache.
*/
- if (page_count(page) != 1 + !!PageSwapCache(page))
+ if (page_count(page) != 1 + !!PageSwapCache(page)) {
+ result = SCAN_PAGE_COUNT;
goto out_unmap;
+ }
if (pte_young(pteval) ||
page_is_young(page) || PageReferenced(page) ||
mmu_notifier_test_young(vma->vm_mm, address))
referenced = true;
}
- if (referenced && writable)
- ret = 1;
+ if (writable) {
+ if (referenced) {
+ result = SCAN_SUCCEED;
+ ret = 1;
+ } else {
+ result = SCAN_NO_REFERENCED_PAGE;
+ }
+ } else {
+ result = SCAN_PAGE_RO;
+ }
out_unmap:
pte_unmap_unlock(pte, ptl);
if (ret) {
collapse_huge_page(mm, address, hpage, vma, node);
}
out:
+ trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced,
+ none_or_zero, result);
return ret;
}
pmd_t _pmd;
int i;
- pmdp_huge_clear_flush_notify(vma, haddr, pmd);
/* leave pmd empty until pte is filled */
+ pmdp_huge_clear_flush_notify(vma, haddr, pmd);
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
pmd_populate(mm, &_pmd, pgtable);
put_huge_zero_page();
}
-void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
- pmd_t *pmd)
+static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long haddr)
{
- spinlock_t *ptl;
- struct page *page = NULL;
struct mm_struct *mm = vma->vm_mm;
- unsigned long haddr = address & HPAGE_PMD_MASK;
- unsigned long mmun_start; /* For mmu_notifiers */
- unsigned long mmun_end; /* For mmu_notifiers */
+ struct page *page;
+ pgtable_t pgtable;
+ pmd_t _pmd;
+ bool young, write;
+ int i;
- BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
+ VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
+ VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
+ VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
+ VM_BUG_ON(!pmd_trans_huge(*pmd));
+
+ count_vm_event(THP_SPLIT_PMD);
- mmun_start = haddr;
- mmun_end = haddr + HPAGE_PMD_SIZE;
-again:
- mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
- ptl = pmd_lock(mm, pmd);
- if (unlikely(!pmd_trans_huge(*pmd)))
- goto unlock;
if (vma_is_dax(vma)) {
pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
if (is_huge_zero_pmd(_pmd))
put_huge_zero_page();
+ return;
} else if (is_huge_zero_pmd(*pmd)) {
- __split_huge_zero_page_pmd(vma, haddr, pmd);
- } else {
- page = pmd_page(*pmd);
- VM_BUG_ON_PAGE(!page_count(page), page);
- get_page(page);
+ return __split_huge_zero_page_pmd(vma, haddr, pmd);
}
- unlock:
- spin_unlock(ptl);
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
- if (!page)
- return;
+ page = pmd_page(*pmd);
+ VM_BUG_ON_PAGE(!page_count(page), page);
+ atomic_add(HPAGE_PMD_NR - 1, &page->_count);
+ write = pmd_write(*pmd);
+ young = pmd_young(*pmd);
- split_huge_page(page);
- put_page(page);
+ /* leave pmd empty until pte is filled */
+ pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+
+ pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+ pmd_populate(mm, &_pmd, pgtable);
+
+ for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+ pte_t entry, *pte;
+ /*
+ * Note that NUMA hinting access restrictions are not
+ * transferred to avoid any possibility of altering
+ * permissions across VMAs.
+ */
+ entry = mk_pte(page + i, vma->vm_page_prot);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ if (!write)
+ entry = pte_wrprotect(entry);
+ if (!young)
+ entry = pte_mkold(entry);
+ pte = pte_offset_map(&_pmd, haddr);
+ BUG_ON(!pte_none(*pte));
+ set_pte_at(mm, haddr, pte, entry);
+ atomic_inc(&page[i]._mapcount);
+ pte_unmap(pte);
+ }
/*
- * We don't always have down_write of mmap_sem here: a racing
- * do_huge_pmd_wp_page() might have copied-on-write to another
- * huge page before our split_huge_page() got the anon_vma lock.
+ * Set PG_double_map before dropping compound_mapcount to avoid
+ * false-negative page_mapped().
*/
- if (unlikely(pmd_trans_huge(*pmd)))
- goto again;
+ if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
+ for (i = 0; i < HPAGE_PMD_NR; i++)
+ atomic_inc(&page[i]._mapcount);
+ }
+
+ if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
+ /* Last compound_mapcount is gone. */
+ __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+ if (TestClearPageDoubleMap(page)) {
+ /* No need in mapcount reference anymore */
+ for (i = 0; i < HPAGE_PMD_NR; i++)
+ atomic_dec(&page[i]._mapcount);
+ }
+ }
+
+ smp_wmb(); /* make pte visible before pmd */
+ pmd_populate(mm, pmd, pgtable);
}
-void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
- pmd_t *pmd)
+void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long address)
{
- struct vm_area_struct *vma;
+ spinlock_t *ptl;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long haddr = address & HPAGE_PMD_MASK;
- vma = find_vma(mm, address);
- BUG_ON(vma == NULL);
- split_huge_page_pmd(vma, address, pmd);
+ mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
+ ptl = pmd_lock(mm, pmd);
+ if (likely(pmd_trans_huge(*pmd)))
+ __split_huge_pmd_locked(vma, pmd, haddr);
+ spin_unlock(ptl);
+ mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
}
-static void split_huge_page_address(struct mm_struct *mm,
+static void split_huge_pmd_address(struct vm_area_struct *vma,
unsigned long address)
{
pgd_t *pgd;
VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
- pgd = pgd_offset(mm, address);
+ pgd = pgd_offset(vma->vm_mm, address);
if (!pgd_present(*pgd))
return;
return;
pmd = pmd_offset(pud, address);
- if (!pmd_present(*pmd))
+ if (!pmd_present(*pmd) || !pmd_trans_huge(*pmd))
return;
/*
* Caller holds the mmap_sem write mode, so a huge pmd cannot
* materialize from under us.
*/
- split_huge_page_pmd_mm(mm, address, pmd);
+ split_huge_pmd(vma, pmd, address);
}
void vma_adjust_trans_huge(struct vm_area_struct *vma,
if (start & ~HPAGE_PMD_MASK &&
(start & HPAGE_PMD_MASK) >= vma->vm_start &&
(start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
- split_huge_page_address(vma->vm_mm, start);
+ split_huge_pmd_address(vma, start);
/*
* If the new end address isn't hpage aligned and it could
if (end & ~HPAGE_PMD_MASK &&
(end & HPAGE_PMD_MASK) >= vma->vm_start &&
(end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
- split_huge_page_address(vma->vm_mm, end);
+ split_huge_pmd_address(vma, end);
/*
* If we're also updating the vma->vm_next->vm_start, if the new
if (nstart & ~HPAGE_PMD_MASK &&
(nstart & HPAGE_PMD_MASK) >= next->vm_start &&
(nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
- split_huge_page_address(next->vm_mm, nstart);
+ split_huge_pmd_address(next, nstart);
}
}
projects / cascardo / linux.git / blobdiff