#include <asm/tlb.h>
#include <asm/pgalloc.h>
#include "internal.h"
+#include "mm_slot.h"
enum scan_result {
SCAN_FAIL,
SCAN_SUCCEED,
SCAN_PMD_NULL,
+ SCAN_PMD_NONE,
+ SCAN_PMD_MAPPED,
SCAN_EXCEED_NONE_PTE,
SCAN_EXCEED_SWAP_PTE,
SCAN_EXCEED_SHARED_PTE,
SCAN_PTE_NON_PRESENT,
SCAN_PTE_UFFD_WP,
+ SCAN_PTE_MAPPED_HUGEPAGE,
SCAN_PAGE_RO,
SCAN_LACK_REFERENCED_PAGE,
SCAN_PAGE_NULL,
* default collapse hugepages if there is at least one pte mapped like
* it would have happened if the vma was large enough during page
* fault.
+ *
+ * Note that these are only respected if collapse was initiated by khugepaged.
*/
static unsigned int khugepaged_max_ptes_none __read_mostly;
static unsigned int khugepaged_max_ptes_swap __read_mostly;
#define MAX_PTE_MAPPED_THP 8
+struct collapse_control {
+ bool is_khugepaged;
+
+ /* Num pages scanned per node */
+ u32 node_load[MAX_NUMNODES];
+
+ /* Last target selected in hpage_collapse_find_target_node() */
+ int last_target_node;
+};
+
/**
- * struct mm_slot - hash lookup from mm to mm_slot
- * @hash: hash collision list
- * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
- * @mm: the mm that this information is valid for
+ * struct khugepaged_mm_slot - khugepaged information per mm that is being scanned
+ * @slot: hash lookup from mm to mm_slot
* @nr_pte_mapped_thp: number of pte mapped THP
* @pte_mapped_thp: address array corresponding pte mapped THP
*/
-struct mm_slot {
- struct hlist_node hash;
- struct list_head mm_node;
- struct mm_struct *mm;
+struct khugepaged_mm_slot {
+ struct mm_slot slot;
/* pte-mapped THP in this mm */
int nr_pte_mapped_thp;
*/
struct khugepaged_scan {
struct list_head mm_head;
- struct mm_slot *mm_slot;
+ struct khugepaged_mm_slot *mm_slot;
unsigned long address;
};
int __init khugepaged_init(void)
{
mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
- sizeof(struct mm_slot),
- __alignof__(struct mm_slot), 0, NULL);
+ sizeof(struct khugepaged_mm_slot),
+ __alignof__(struct khugepaged_mm_slot),
+ 0, NULL);
if (!mm_slot_cache)
return -ENOMEM;
kmem_cache_destroy(mm_slot_cache);
}
-static inline struct mm_slot *alloc_mm_slot(void)
-{
- if (!mm_slot_cache) /* initialization failed */
- return NULL;
- return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
-}
-
-static inline void free_mm_slot(struct mm_slot *mm_slot)
-{
- kmem_cache_free(mm_slot_cache, mm_slot);
-}
-
-static struct mm_slot *get_mm_slot(struct mm_struct *mm)
-{
- struct mm_slot *mm_slot;
-
- hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
- if (mm == mm_slot->mm)
- return mm_slot;
-
- return NULL;
-}
-
-static void insert_to_mm_slots_hash(struct mm_struct *mm,
- struct mm_slot *mm_slot)
-{
- mm_slot->mm = mm;
- hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
-}
-
-static inline int khugepaged_test_exit(struct mm_struct *mm)
+static inline int hpage_collapse_test_exit(struct mm_struct *mm)
{
return atomic_read(&mm->mm_users) == 0;
}
void __khugepaged_enter(struct mm_struct *mm)
{
- struct mm_slot *mm_slot;
+ struct khugepaged_mm_slot *mm_slot;
+ struct mm_slot *slot;
int wakeup;
- mm_slot = alloc_mm_slot();
+ mm_slot = mm_slot_alloc(mm_slot_cache);
if (!mm_slot)
return;
+ slot = &mm_slot->slot;
+
/* __khugepaged_exit() must not run from under us */
- VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
+ VM_BUG_ON_MM(hpage_collapse_test_exit(mm), mm);
if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
- free_mm_slot(mm_slot);
+ mm_slot_free(mm_slot_cache, mm_slot);
return;
}
spin_lock(&khugepaged_mm_lock);
- insert_to_mm_slots_hash(mm, mm_slot);
+ mm_slot_insert(mm_slots_hash, mm, slot);
/*
* Insert just behind the scanning cursor, to let the area settle
* down a little.
*/
wakeup = list_empty(&khugepaged_scan.mm_head);
- list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
+ list_add_tail(&slot->mm_node, &khugepaged_scan.mm_head);
spin_unlock(&khugepaged_mm_lock);
mmgrab(mm);
{
if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
hugepage_flags_enabled()) {
- if (hugepage_vma_check(vma, vm_flags, false, false))
+ if (hugepage_vma_check(vma, vm_flags, false, false, true))
__khugepaged_enter(vma->vm_mm);
}
}
void __khugepaged_exit(struct mm_struct *mm)
{
- struct mm_slot *mm_slot;
+ struct khugepaged_mm_slot *mm_slot;
+ struct mm_slot *slot;
int free = 0;
spin_lock(&khugepaged_mm_lock);
- mm_slot = get_mm_slot(mm);
+ slot = mm_slot_lookup(mm_slots_hash, mm);
+ mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
- hash_del(&mm_slot->hash);
- list_del(&mm_slot->mm_node);
+ hash_del(&slot->hash);
+ list_del(&slot->mm_node);
free = 1;
}
spin_unlock(&khugepaged_mm_lock);
if (free) {
clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
- free_mm_slot(mm_slot);
+ mm_slot_free(mm_slot_cache, mm_slot);
mmdrop(mm);
} else if (mm_slot) {
/*
* This is required to serialize against
- * khugepaged_test_exit() (which is guaranteed to run
- * under mmap sem read mode). Stop here (after we
- * return all pagetables will be destroyed) until
- * khugepaged has finished working on the pagetables
- * under the mmap_lock.
+ * hpage_collapse_test_exit() (which is guaranteed to run
+ * under mmap sem read mode). Stop here (after we return all
+ * pagetables will be destroyed) until khugepaged has finished
+ * working on the pagetables under the mmap_lock.
*/
mmap_write_lock(mm);
mmap_write_unlock(mm);
static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
unsigned long address,
pte_t *pte,
+ struct collapse_control *cc,
struct list_head *compound_pagelist)
{
struct page *page = NULL;
pte_t *_pte;
- int none_or_zero = 0, shared = 0, result = 0, referenced = 0;
+ int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0;
bool writable = false;
for (_pte = pte; _pte < pte + HPAGE_PMD_NR;
pte_t pteval = *_pte;
if (pte_none(pteval) || (pte_present(pteval) &&
is_zero_pfn(pte_pfn(pteval)))) {
+ ++none_or_zero;
if (!userfaultfd_armed(vma) &&
- ++none_or_zero <= khugepaged_max_ptes_none) {
+ (!cc->is_khugepaged ||
+ none_or_zero <= khugepaged_max_ptes_none)) {
continue;
} else {
result = SCAN_EXCEED_NONE_PTE;
VM_BUG_ON_PAGE(!PageAnon(page), page);
- if (page_mapcount(page) > 1 &&
- ++shared > khugepaged_max_ptes_shared) {
- result = SCAN_EXCEED_SHARED_PTE;
- count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
- goto out;
+ if (page_mapcount(page) > 1) {
+ ++shared;
+ if (cc->is_khugepaged &&
+ shared > khugepaged_max_ptes_shared) {
+ result = SCAN_EXCEED_SHARED_PTE;
+ count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
+ goto out;
+ }
}
if (PageCompound(page)) {
if (PageCompound(page))
list_add_tail(&page->lru, compound_pagelist);
next:
- /* There should be enough young pte to collapse the page */
- if (pte_young(pteval) ||
- page_is_young(page) || PageReferenced(page) ||
- mmu_notifier_test_young(vma->vm_mm, address))
+ /*
+ * If collapse was initiated by khugepaged, check that there is
+ * enough young pte to justify collapsing the page
+ */
+ if (cc->is_khugepaged &&
+ (pte_young(pteval) || page_is_young(page) ||
+ PageReferenced(page) || mmu_notifier_test_young(vma->vm_mm,
+ address)))
referenced++;
if (pte_write(pteval))
if (unlikely(!writable)) {
result = SCAN_PAGE_RO;
- } else if (unlikely(!referenced)) {
+ } else if (unlikely(cc->is_khugepaged && !referenced)) {
result = SCAN_LACK_REFERENCED_PAGE;
} else {
result = SCAN_SUCCEED;
trace_mm_collapse_huge_page_isolate(page, none_or_zero,
referenced, writable, result);
- return 1;
+ return result;
}
out:
release_pte_pages(pte, _pte, compound_pagelist);
trace_mm_collapse_huge_page_isolate(page, none_or_zero,
referenced, writable, result);
- return 0;
+ return result;
}
static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
DEFINE_WAIT(wait);
add_wait_queue(&khugepaged_wait, &wait);
- freezable_schedule_timeout_interruptible(
- msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
+ __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
+ schedule_timeout(msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
remove_wait_queue(&khugepaged_wait, &wait);
}
-static int khugepaged_node_load[MAX_NUMNODES];
+struct collapse_control khugepaged_collapse_control = {
+ .is_khugepaged = true,
+ .last_target_node = NUMA_NO_NODE,
+};
-static bool khugepaged_scan_abort(int nid)
+static bool hpage_collapse_scan_abort(int nid, struct collapse_control *cc)
{
int i;
return false;
/* If there is a count for this node already, it must be acceptable */
- if (khugepaged_node_load[nid])
+ if (cc->node_load[nid])
return false;
for (i = 0; i < MAX_NUMNODES; i++) {
- if (!khugepaged_node_load[i])
+ if (!cc->node_load[i])
continue;
if (node_distance(nid, i) > node_reclaim_distance)
return true;
}
#ifdef CONFIG_NUMA
-static int khugepaged_find_target_node(void)
+static int hpage_collapse_find_target_node(struct collapse_control *cc)
{
- static int last_khugepaged_target_node = NUMA_NO_NODE;
int nid, target_node = 0, max_value = 0;
/* find first node with max normal pages hit */
for (nid = 0; nid < MAX_NUMNODES; nid++)
- if (khugepaged_node_load[nid] > max_value) {
- max_value = khugepaged_node_load[nid];
+ if (cc->node_load[nid] > max_value) {
+ max_value = cc->node_load[nid];
target_node = nid;
}
/* do some balance if several nodes have the same hit record */
- if (target_node <= last_khugepaged_target_node)
- for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
- nid++)
- if (max_value == khugepaged_node_load[nid]) {
+ if (target_node <= cc->last_target_node)
+ for (nid = cc->last_target_node + 1; nid < MAX_NUMNODES;
+ nid++)
+ if (max_value == cc->node_load[nid]) {
target_node = nid;
break;
}
- last_khugepaged_target_node = target_node;
+ cc->last_target_node = target_node;
return target_node;
}
-
-static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+#else
+static int hpage_collapse_find_target_node(struct collapse_control *cc)
{
- if (IS_ERR(*hpage)) {
- if (!*wait)
- return false;
-
- *wait = false;
- *hpage = NULL;
- khugepaged_alloc_sleep();
- } else if (*hpage) {
- put_page(*hpage);
- *hpage = NULL;
- }
-
- return true;
+ return 0;
}
+#endif
-static struct page *
-khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node)
+static bool hpage_collapse_alloc_page(struct page **hpage, gfp_t gfp, int node)
{
- VM_BUG_ON_PAGE(*hpage, *hpage);
-
*hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
if (unlikely(!*hpage)) {
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
- *hpage = ERR_PTR(-ENOMEM);
- return NULL;
+ return false;
}
prep_transhuge_page(*hpage);
count_vm_event(THP_COLLAPSE_ALLOC);
- return *hpage;
-}
-#else
-static int khugepaged_find_target_node(void)
-{
- return 0;
-}
-
-static inline struct page *alloc_khugepaged_hugepage(void)
-{
- struct page *page;
-
- page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
- HPAGE_PMD_ORDER);
- if (page)
- prep_transhuge_page(page);
- return page;
-}
-
-static struct page *khugepaged_alloc_hugepage(bool *wait)
-{
- struct page *hpage;
-
- do {
- hpage = alloc_khugepaged_hugepage();
- if (!hpage) {
- count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
- if (!*wait)
- return NULL;
-
- *wait = false;
- khugepaged_alloc_sleep();
- } else
- count_vm_event(THP_COLLAPSE_ALLOC);
- } while (unlikely(!hpage) && likely(hugepage_flags_enabled()));
-
- return hpage;
-}
-
-static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
-{
- /*
- * If the hpage allocated earlier was briefly exposed in page cache
- * before collapse_file() failed, it is possible that racing lookups
- * have not yet completed, and would then be unpleasantly surprised by
- * finding the hpage reused for the same mapping at a different offset.
- * Just release the previous allocation if there is any danger of that.
- */
- if (*hpage && page_count(*hpage) > 1) {
- put_page(*hpage);
- *hpage = NULL;
- }
-
- if (!*hpage)
- *hpage = khugepaged_alloc_hugepage(wait);
-
- if (unlikely(!*hpage))
- return false;
-
return true;
}
-static struct page *
-khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node)
-{
- VM_BUG_ON(!*hpage);
-
- return *hpage;
-}
-#endif
-
/*
* If mmap_lock temporarily dropped, revalidate vma
* before taking mmap_lock.
- * Return 0 if succeeds, otherwise return none-zero
- * value (scan code).
+ * Returns enum scan_result value.
*/
static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
- struct vm_area_struct **vmap)
+ bool expect_anon,
+ struct vm_area_struct **vmap,
+ struct collapse_control *cc)
{
struct vm_area_struct *vma;
- if (unlikely(khugepaged_test_exit(mm)))
+ if (unlikely(hpage_collapse_test_exit(mm)))
return SCAN_ANY_PROCESS;
*vmap = vma = find_vma(mm, address);
if (!transhuge_vma_suitable(vma, address))
return SCAN_ADDRESS_RANGE;
- if (!hugepage_vma_check(vma, vma->vm_flags, false, false))
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false,
+ cc->is_khugepaged))
return SCAN_VMA_CHECK;
/*
* Anon VMA expected, the address may be unmapped then
* hugepage_vma_check may return true for qualified file
* vmas.
*/
- if (!vma->anon_vma || !vma_is_anonymous(vma))
- return SCAN_VMA_CHECK;
- return 0;
+ if (expect_anon && (!(*vmap)->anon_vma || !vma_is_anonymous(*vmap)))
+ return SCAN_PAGE_ANON;
+ return SCAN_SUCCEED;
+}
+
+static int find_pmd_or_thp_or_none(struct mm_struct *mm,
+ unsigned long address,
+ pmd_t **pmd)
+{
+ pmd_t pmde;
+
+ *pmd = mm_find_pmd(mm, address);
+ if (!*pmd)
+ return SCAN_PMD_NULL;
+
+ pmde = pmd_read_atomic(*pmd);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ /* See comments in pmd_none_or_trans_huge_or_clear_bad() */
+ barrier();
+#endif
+ if (pmd_none(pmde))
+ return SCAN_PMD_NONE;
+ if (pmd_trans_huge(pmde))
+ return SCAN_PMD_MAPPED;
+ if (pmd_bad(pmde))
+ return SCAN_PMD_NULL;
+ return SCAN_SUCCEED;
+}
+
+static int check_pmd_still_valid(struct mm_struct *mm,
+ unsigned long address,
+ pmd_t *pmd)
+{
+ pmd_t *new_pmd;
+ int result = find_pmd_or_thp_or_none(mm, address, &new_pmd);
+
+ if (result != SCAN_SUCCEED)
+ return result;
+ if (new_pmd != pmd)
+ return SCAN_FAIL;
+ return SCAN_SUCCEED;
}
/*
* Bring missing pages in from swap, to complete THP collapse.
- * Only done if khugepaged_scan_pmd believes it is worthwhile.
+ * Only done if hpage_collapse_scan_pmd believes it is worthwhile.
*
* Called and returns without pte mapped or spinlocks held.
* Note that if false is returned, mmap_lock will be released.
*/
-static bool __collapse_huge_page_swapin(struct mm_struct *mm,
- struct vm_area_struct *vma,
- unsigned long haddr, pmd_t *pmd,
- int referenced)
+static int __collapse_huge_page_swapin(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ unsigned long haddr, pmd_t *pmd,
+ int referenced)
{
int swapped_in = 0;
vm_fault_t ret = 0;
*/
if (ret & VM_FAULT_RETRY) {
trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
- return false;
+ /* Likely, but not guaranteed, that page lock failed */
+ return SCAN_PAGE_LOCK;
}
if (ret & VM_FAULT_ERROR) {
mmap_read_unlock(mm);
trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
- return false;
+ return SCAN_FAIL;
}
swapped_in++;
}
lru_add_drain();
trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1);
- return true;
+ return SCAN_SUCCEED;
}
-static void collapse_huge_page(struct mm_struct *mm,
- unsigned long address,
- struct page **hpage,
- int node, int referenced, int unmapped)
+static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
+ struct collapse_control *cc)
+{
+ /* Only allocate from the target node */
+ gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
+ GFP_TRANSHUGE) | __GFP_THISNODE;
+ int node = hpage_collapse_find_target_node(cc);
+
+ if (!hpage_collapse_alloc_page(hpage, gfp, node))
+ return SCAN_ALLOC_HUGE_PAGE_FAIL;
+ if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
+ return SCAN_CGROUP_CHARGE_FAIL;
+ count_memcg_page_event(*hpage, THP_COLLAPSE_ALLOC);
+ return SCAN_SUCCEED;
+}
+
+static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
+ int referenced, int unmapped,
+ struct collapse_control *cc)
{
LIST_HEAD(compound_pagelist);
pmd_t *pmd, _pmd;
pte_t *pte;
pgtable_t pgtable;
- struct page *new_page;
+ struct page *hpage;
spinlock_t *pmd_ptl, *pte_ptl;
- int isolated = 0, result = 0;
+ int result = SCAN_FAIL;
struct vm_area_struct *vma;
struct mmu_notifier_range range;
- gfp_t gfp;
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
- /* Only allocate from the target node */
- gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE;
-
/*
* Before allocating the hugepage, release the mmap_lock read lock.
* The allocation can take potentially a long time if it involves
* that. We will recheck the vma after taking it again in write mode.
*/
mmap_read_unlock(mm);
- new_page = khugepaged_alloc_page(hpage, gfp, node);
- if (!new_page) {
- result = SCAN_ALLOC_HUGE_PAGE_FAIL;
- goto out_nolock;
- }
- if (unlikely(mem_cgroup_charge(page_folio(new_page), mm, gfp))) {
- result = SCAN_CGROUP_CHARGE_FAIL;
+ result = alloc_charge_hpage(&hpage, mm, cc);
+ if (result != SCAN_SUCCEED)
goto out_nolock;
- }
- count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC);
mmap_read_lock(mm);
- result = hugepage_vma_revalidate(mm, address, &vma);
- if (result) {
+ result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
+ if (result != SCAN_SUCCEED) {
mmap_read_unlock(mm);
goto out_nolock;
}
- pmd = mm_find_pmd(mm, address);
- if (!pmd) {
- result = SCAN_PMD_NULL;
+ result = find_pmd_or_thp_or_none(mm, address, &pmd);
+ if (result != SCAN_SUCCEED) {
mmap_read_unlock(mm);
goto out_nolock;
}
- /*
- * __collapse_huge_page_swapin will return with mmap_lock released
- * when it fails. So we jump out_nolock directly in that case.
- * Continuing to collapse causes inconsistency.
- */
- if (unmapped && !__collapse_huge_page_swapin(mm, vma, address,
- pmd, referenced)) {
- goto out_nolock;
+ if (unmapped) {
+ /*
+ * __collapse_huge_page_swapin will return with mmap_lock
+ * released when it fails. So we jump out_nolock directly in
+ * that case. Continuing to collapse causes inconsistency.
+ */
+ result = __collapse_huge_page_swapin(mm, vma, address, pmd,
+ referenced);
+ if (result != SCAN_SUCCEED)
+ goto out_nolock;
}
mmap_read_unlock(mm);
* handled by the anon_vma lock + PG_lock.
*/
mmap_write_lock(mm);
- result = hugepage_vma_revalidate(mm, address, &vma);
- if (result)
+ result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
+ if (result != SCAN_SUCCEED)
goto out_up_write;
/* check if the pmd is still valid */
- if (mm_find_pmd(mm, address) != pmd)
+ result = check_pmd_still_valid(mm, address, pmd);
+ if (result != SCAN_SUCCEED)
goto out_up_write;
anon_vma_lock_write(vma->anon_vma);
mmu_notifier_invalidate_range_end(&range);
spin_lock(pte_ptl);
- isolated = __collapse_huge_page_isolate(vma, address, pte,
- &compound_pagelist);
+ result = __collapse_huge_page_isolate(vma, address, pte, cc,
+ &compound_pagelist);
spin_unlock(pte_ptl);
- if (unlikely(!isolated)) {
+ if (unlikely(result != SCAN_SUCCEED)) {
pte_unmap(pte);
spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
pmd_populate(mm, pmd, pmd_pgtable(_pmd));
spin_unlock(pmd_ptl);
anon_vma_unlock_write(vma->anon_vma);
- result = SCAN_FAIL;
goto out_up_write;
}
*/
anon_vma_unlock_write(vma->anon_vma);
- __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl,
- &compound_pagelist);
+ __collapse_huge_page_copy(pte, hpage, vma, address, pte_ptl,
+ &compound_pagelist);
pte_unmap(pte);
/*
* spin_lock() below is not the equivalent of smp_wmb(), but
* avoid the copy_huge_page writes to become visible after
* the set_pmd_at() write.
*/
- __SetPageUptodate(new_page);
+ __SetPageUptodate(hpage);
pgtable = pmd_pgtable(_pmd);
- _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
+ _pmd = mk_huge_pmd(hpage, vma->vm_page_prot);
_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
- page_add_new_anon_rmap(new_page, vma, address);
- lru_cache_add_inactive_or_unevictable(new_page, vma);
+ page_add_new_anon_rmap(hpage, vma, address);
+ lru_cache_add_inactive_or_unevictable(hpage, vma);
pgtable_trans_huge_deposit(mm, pmd, pgtable);
set_pmd_at(mm, address, pmd, _pmd);
update_mmu_cache_pmd(vma, address, pmd);
spin_unlock(pmd_ptl);
- *hpage = NULL;
+ hpage = NULL;
- khugepaged_pages_collapsed++;
result = SCAN_SUCCEED;
out_up_write:
mmap_write_unlock(mm);
out_nolock:
- if (!IS_ERR_OR_NULL(*hpage))
- mem_cgroup_uncharge(page_folio(*hpage));
- trace_mm_collapse_huge_page(mm, isolated, result);
- return;
+ if (hpage) {
+ mem_cgroup_uncharge(page_folio(hpage));
+ put_page(hpage);
+ }
+ trace_mm_collapse_huge_page(mm, result == SCAN_SUCCEED, result);
+ return result;
}
-static int khugepaged_scan_pmd(struct mm_struct *mm,
- struct vm_area_struct *vma,
- unsigned long address,
- struct page **hpage)
+static int hpage_collapse_scan_pmd(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ unsigned long address, bool *mmap_locked,
+ struct collapse_control *cc)
{
pmd_t *pmd;
pte_t *pte, *_pte;
- int ret = 0, result = 0, referenced = 0;
+ int result = SCAN_FAIL, referenced = 0;
int none_or_zero = 0, shared = 0;
struct page *page = NULL;
unsigned long _address;
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
- pmd = mm_find_pmd(mm, address);
- if (!pmd) {
- result = SCAN_PMD_NULL;
+ result = find_pmd_or_thp_or_none(mm, address, &pmd);
+ if (result != SCAN_SUCCEED)
goto out;
- }
- memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
+ memset(cc->node_load, 0, sizeof(cc->node_load));
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
for (_address = address, _pte = pte; _pte < pte + HPAGE_PMD_NR;
_pte++, _address += PAGE_SIZE) {
pte_t pteval = *_pte;
if (is_swap_pte(pteval)) {
- if (++unmapped <= khugepaged_max_ptes_swap) {
+ ++unmapped;
+ if (!cc->is_khugepaged ||
+ unmapped <= khugepaged_max_ptes_swap) {
/*
* Always be strict with uffd-wp
* enabled swap entries. Please see
}
}
if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+ ++none_or_zero;
if (!userfaultfd_armed(vma) &&
- ++none_or_zero <= khugepaged_max_ptes_none) {
+ (!cc->is_khugepaged ||
+ none_or_zero <= khugepaged_max_ptes_none)) {
continue;
} else {
result = SCAN_EXCEED_NONE_PTE;
goto out_unmap;
}
- if (page_mapcount(page) > 1 &&
- ++shared > khugepaged_max_ptes_shared) {
- result = SCAN_EXCEED_SHARED_PTE;
- count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
- goto out_unmap;
+ if (page_mapcount(page) > 1) {
+ ++shared;
+ if (cc->is_khugepaged &&
+ shared > khugepaged_max_ptes_shared) {
+ result = SCAN_EXCEED_SHARED_PTE;
+ count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
+ goto out_unmap;
+ }
}
page = compound_head(page);
/*
* Record which node the original page is from and save this
- * information to khugepaged_node_load[].
+ * information to cc->node_load[].
* Khugepaged will allocate hugepage from the node has the max
* hit record.
*/
node = page_to_nid(page);
- if (khugepaged_scan_abort(node)) {
+ if (hpage_collapse_scan_abort(node, cc)) {
result = SCAN_SCAN_ABORT;
goto out_unmap;
}
- khugepaged_node_load[node]++;
+ cc->node_load[node]++;
if (!PageLRU(page)) {
result = SCAN_PAGE_LRU;
goto out_unmap;
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))
+
+ /*
+ * If collapse was initiated by khugepaged, check that there is
+ * enough young pte to justify collapsing the page
+ */
+ if (cc->is_khugepaged &&
+ (pte_young(pteval) || page_is_young(page) ||
+ PageReferenced(page) || mmu_notifier_test_young(vma->vm_mm,
+ address)))
referenced++;
}
if (!writable) {
result = SCAN_PAGE_RO;
- } else if (!referenced || (unmapped && referenced < HPAGE_PMD_NR/2)) {
+ } else if (cc->is_khugepaged &&
+ (!referenced ||
+ (unmapped && referenced < HPAGE_PMD_NR / 2))) {
result = SCAN_LACK_REFERENCED_PAGE;
} else {
result = SCAN_SUCCEED;
- ret = 1;
}
out_unmap:
pte_unmap_unlock(pte, ptl);
- if (ret) {
- node = khugepaged_find_target_node();
+ if (result == SCAN_SUCCEED) {
+ result = collapse_huge_page(mm, address, referenced,
+ unmapped, cc);
/* collapse_huge_page will return with the mmap_lock released */
- collapse_huge_page(mm, address, hpage, node,
- referenced, unmapped);
+ *mmap_locked = false;
}
out:
trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
none_or_zero, result, unmapped);
- return ret;
+ return result;
}
-static void collect_mm_slot(struct mm_slot *mm_slot)
+static void collect_mm_slot(struct khugepaged_mm_slot *mm_slot)
{
- struct mm_struct *mm = mm_slot->mm;
+ struct mm_slot *slot = &mm_slot->slot;
+ struct mm_struct *mm = slot->mm;
lockdep_assert_held(&khugepaged_mm_lock);
- if (khugepaged_test_exit(mm)) {
+ if (hpage_collapse_test_exit(mm)) {
/* free mm_slot */
- hash_del(&mm_slot->hash);
- list_del(&mm_slot->mm_node);
+ hash_del(&slot->hash);
+ list_del(&slot->mm_node);
/*
* Not strictly needed because the mm exited already.
*/
/* khugepaged_mm_lock actually not necessary for the below */
- free_mm_slot(mm_slot);
+ mm_slot_free(mm_slot_cache, mm_slot);
mmdrop(mm);
}
}
/*
* Notify khugepaged that given addr of the mm is pte-mapped THP. Then
* khugepaged should try to collapse the page table.
+ *
+ * Note that following race exists:
+ * (1) khugepaged calls khugepaged_collapse_pte_mapped_thps() for mm_struct A,
+ * emptying the A's ->pte_mapped_thp[] array.
+ * (2) MADV_COLLAPSE collapses some file extent with target mm_struct B, and
+ * retract_page_tables() finds a VMA in mm_struct A mapping the same extent
+ * (at virtual address X) and adds an entry (for X) into mm_struct A's
+ * ->pte-mapped_thp[] array.
+ * (3) khugepaged calls khugepaged_collapse_scan_file() for mm_struct A at X,
+ * sees a pte-mapped THP (SCAN_PTE_MAPPED_HUGEPAGE) and adds an entry
+ * (for X) into mm_struct A's ->pte-mapped_thp[] array.
+ * Thus, it's possible the same address is added multiple times for the same
+ * mm_struct. Should this happen, we'll simply attempt
+ * collapse_pte_mapped_thp() multiple times for the same address, under the same
+ * exclusive mmap_lock, and assuming the first call is successful, subsequent
+ * attempts will return quickly (without grabbing any additional locks) when
+ * a huge pmd is found in find_pmd_or_thp_or_none(). Since this is a cheap
+ * check, and since this is a rare occurrence, the cost of preventing this
+ * "multiple-add" is thought to be more expensive than just handling it, should
+ * it occur.
*/
-static void khugepaged_add_pte_mapped_thp(struct mm_struct *mm,
+static bool khugepaged_add_pte_mapped_thp(struct mm_struct *mm,
unsigned long addr)
{
- struct mm_slot *mm_slot;
+ struct khugepaged_mm_slot *mm_slot;
+ struct mm_slot *slot;
+ bool ret = false;
VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
spin_lock(&khugepaged_mm_lock);
- mm_slot = get_mm_slot(mm);
- if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP))
+ slot = mm_slot_lookup(mm_slots_hash, mm);
+ mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
+ if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) {
mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr;
+ ret = true;
+ }
spin_unlock(&khugepaged_mm_lock);
+ return ret;
+}
+
+/* hpage must be locked, and mmap_lock must be held in write */
+static int set_huge_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmdp, struct page *hpage)
+{
+ struct vm_fault vmf = {
+ .vma = vma,
+ .address = addr,
+ .flags = 0,
+ .pmd = pmdp,
+ };
+
+ VM_BUG_ON(!PageTransHuge(hpage));
+ mmap_assert_write_locked(vma->vm_mm);
+
+ if (do_set_pmd(&vmf, hpage))
+ return SCAN_FAIL;
+
+ get_page(hpage);
+ return SCAN_SUCCEED;
}
static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
*
* @mm: process address space where collapse happens
* @addr: THP collapse address
+ * @install_pmd: If a huge PMD should be installed
*
* This function checks whether all the PTEs in the PMD are pointing to the
* right THP. If so, retract the page table so the THP can refault in with
- * as pmd-mapped.
+ * as pmd-mapped. Possibly install a huge PMD mapping the THP.
*/
-void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
+int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
+ bool install_pmd)
{
unsigned long haddr = addr & HPAGE_PMD_MASK;
- struct vm_area_struct *vma = find_vma(mm, haddr);
+ struct vm_area_struct *vma = vma_lookup(mm, haddr);
struct page *hpage;
pte_t *start_pte, *pte;
pmd_t *pmd;
spinlock_t *ptl;
- int count = 0;
+ int count = 0, result = SCAN_FAIL;
int i;
+ mmap_assert_write_locked(mm);
+
+ /* Fast check before locking page if already PMD-mapped */
+ result = find_pmd_or_thp_or_none(mm, haddr, &pmd);
+ if (result == SCAN_PMD_MAPPED)
+ return result;
+
if (!vma || !vma->vm_file ||
!range_in_vma(vma, haddr, haddr + HPAGE_PMD_SIZE))
- return;
+ return SCAN_VMA_CHECK;
/*
- * This vm_flags may not have VM_HUGEPAGE if the page was not
- * collapsed by this mm. But we can still collapse if the page is
- * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()
- * will not fail the vma for missing VM_HUGEPAGE
+ * If we are here, we've succeeded in replacing all the native pages
+ * in the page cache with a single hugepage. If a mm were to fault-in
+ * this memory (mapped by a suitably aligned VMA), we'd get the hugepage
+ * and map it by a PMD, regardless of sysfs THP settings. As such, let's
+ * analogously elide sysfs THP settings here.
*/
- if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false, false))
- return;
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false))
+ return SCAN_VMA_CHECK;
/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
if (userfaultfd_wp(vma))
- return;
+ return SCAN_PTE_UFFD_WP;
hpage = find_lock_page(vma->vm_file->f_mapping,
linear_page_index(vma, haddr));
if (!hpage)
- return;
+ return SCAN_PAGE_NULL;
+
+ if (!PageHead(hpage)) {
+ result = SCAN_FAIL;
+ goto drop_hpage;
+ }
- if (!PageHead(hpage))
+ if (compound_order(hpage) != HPAGE_PMD_ORDER) {
+ result = SCAN_PAGE_COMPOUND;
goto drop_hpage;
+ }
- pmd = mm_find_pmd(mm, haddr);
- if (!pmd)
+ switch (result) {
+ case SCAN_SUCCEED:
+ break;
+ case SCAN_PMD_NONE:
+ /*
+ * In MADV_COLLAPSE path, possible race with khugepaged where
+ * all pte entries have been removed and pmd cleared. If so,
+ * skip all the pte checks and just update the pmd mapping.
+ */
+ goto maybe_install_pmd;
+ default:
goto drop_hpage;
+ }
start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl);
+ result = SCAN_FAIL;
/* step 1: check all mapped PTEs are to the right huge page */
for (i = 0, addr = haddr, pte = start_pte;
continue;
/* page swapped out, abort */
- if (!pte_present(*pte))
+ if (!pte_present(*pte)) {
+ result = SCAN_PTE_NON_PRESENT;
goto abort;
+ }
page = vm_normal_page(vma, addr, *pte);
if (WARN_ON_ONCE(page && is_zone_device_page(page)))
add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count);
}
- /* step 4: collapse pmd */
+ /* step 4: remove pte entries */
collapse_and_free_pmd(mm, vma, haddr, pmd);
+
+maybe_install_pmd:
+ /* step 5: install pmd entry */
+ result = install_pmd
+ ? set_huge_pmd(vma, haddr, pmd, hpage)
+ : SCAN_SUCCEED;
+
drop_hpage:
unlock_page(hpage);
put_page(hpage);
- return;
+ return result;
abort:
pte_unmap_unlock(start_pte, ptl);
goto drop_hpage;
}
-static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot)
+static void khugepaged_collapse_pte_mapped_thps(struct khugepaged_mm_slot *mm_slot)
{
- struct mm_struct *mm = mm_slot->mm;
+ struct mm_slot *slot = &mm_slot->slot;
+ struct mm_struct *mm = slot->mm;
int i;
if (likely(mm_slot->nr_pte_mapped_thp == 0))
if (!mmap_write_trylock(mm))
return;
- if (unlikely(khugepaged_test_exit(mm)))
+ if (unlikely(hpage_collapse_test_exit(mm)))
goto out;
for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++)
- collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]);
+ collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i], false);
out:
mm_slot->nr_pte_mapped_thp = 0;
mmap_write_unlock(mm);
}
-static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
+static int retract_page_tables(struct address_space *mapping, pgoff_t pgoff,
+ struct mm_struct *target_mm,
+ unsigned long target_addr, struct page *hpage,
+ struct collapse_control *cc)
{
struct vm_area_struct *vma;
- struct mm_struct *mm;
- unsigned long addr;
- pmd_t *pmd;
+ int target_result = SCAN_FAIL;
i_mmap_lock_write(mapping);
vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
+ int result = SCAN_FAIL;
+ struct mm_struct *mm = NULL;
+ unsigned long addr = 0;
+ pmd_t *pmd;
+ bool is_target = false;
+
/*
* Check vma->anon_vma to exclude MAP_PRIVATE mappings that
* got written to. These VMAs are likely not worth investing
* ptl. It has higher chance to recover THP for the VMA, but
* has higher cost too.
*/
- if (vma->anon_vma)
- continue;
+ if (vma->anon_vma) {
+ result = SCAN_PAGE_ANON;
+ goto next;
+ }
addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
- if (addr & ~HPAGE_PMD_MASK)
- continue;
- if (vma->vm_end < addr + HPAGE_PMD_SIZE)
- continue;
+ if (addr & ~HPAGE_PMD_MASK ||
+ vma->vm_end < addr + HPAGE_PMD_SIZE) {
+ result = SCAN_VMA_CHECK;
+ goto next;
+ }
mm = vma->vm_mm;
- pmd = mm_find_pmd(mm, addr);
- if (!pmd)
- continue;
+ is_target = mm == target_mm && addr == target_addr;
+ result = find_pmd_or_thp_or_none(mm, addr, &pmd);
+ if (result != SCAN_SUCCEED)
+ goto next;
/*
* We need exclusive mmap_lock to retract page table.
*
* We use trylock due to lock inversion: we need to acquire
* mmap_lock while holding page lock. Fault path does it in
* reverse order. Trylock is a way to avoid deadlock.
+ *
+ * Also, it's not MADV_COLLAPSE's job to collapse other
+ * mappings - let khugepaged take care of them later.
*/
- if (mmap_write_trylock(mm)) {
+ result = SCAN_PTE_MAPPED_HUGEPAGE;
+ if ((cc->is_khugepaged || is_target) &&
+ mmap_write_trylock(mm)) {
/*
* When a vma is registered with uffd-wp, we can't
* recycle the pmd pgtable because there can be pte
* it'll always mapped in small page size for uffd-wp
* registered ranges.
*/
- if (!khugepaged_test_exit(mm) && !userfaultfd_wp(vma))
- collapse_and_free_pmd(mm, vma, addr, pmd);
+ if (hpage_collapse_test_exit(mm)) {
+ result = SCAN_ANY_PROCESS;
+ goto unlock_next;
+ }
+ if (userfaultfd_wp(vma)) {
+ result = SCAN_PTE_UFFD_WP;
+ goto unlock_next;
+ }
+ collapse_and_free_pmd(mm, vma, addr, pmd);
+ if (!cc->is_khugepaged && is_target)
+ result = set_huge_pmd(vma, addr, pmd, hpage);
+ else
+ result = SCAN_SUCCEED;
+
+unlock_next:
mmap_write_unlock(mm);
- } else {
- /* Try again later */
+ goto next;
+ }
+ /*
+ * Calling context will handle target mm/addr. Otherwise, let
+ * khugepaged try again later.
+ */
+ if (!is_target) {
khugepaged_add_pte_mapped_thp(mm, addr);
+ continue;
}
+next:
+ if (is_target)
+ target_result = result;
}
i_mmap_unlock_write(mapping);
+ return target_result;
}
/**
* collapse_file - collapse filemap/tmpfs/shmem pages into huge one.
*
* @mm: process address space where collapse happens
+ * @addr: virtual collapse start address
* @file: file that collapse on
* @start: collapse start address
- * @hpage: new allocated huge page for collapse
- * @node: appointed node the new huge page allocate from
+ * @cc: collapse context and scratchpad
*
* Basic scheme is simple, details are more complex:
* - allocate and lock a new huge page;
* + restore gaps in the page cache;
* + unlock and free huge page;
*/
-static void collapse_file(struct mm_struct *mm,
- struct file *file, pgoff_t start,
- struct page **hpage, int node)
+static int collapse_file(struct mm_struct *mm, unsigned long addr,
+ struct file *file, pgoff_t start,
+ struct collapse_control *cc)
{
struct address_space *mapping = file->f_mapping;
- gfp_t gfp;
- struct page *new_page;
+ struct page *hpage;
pgoff_t index, end = start + HPAGE_PMD_NR;
LIST_HEAD(pagelist);
XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER);
VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
- /* Only allocate from the target node */
- gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE;
-
- new_page = khugepaged_alloc_page(hpage, gfp, node);
- if (!new_page) {
- result = SCAN_ALLOC_HUGE_PAGE_FAIL;
- goto out;
- }
-
- if (unlikely(mem_cgroup_charge(page_folio(new_page), mm, gfp))) {
- result = SCAN_CGROUP_CHARGE_FAIL;
+ result = alloc_charge_hpage(&hpage, mm, cc);
+ if (result != SCAN_SUCCEED)
goto out;
- }
- count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC);
/*
* Ensure we have slots for all the pages in the range. This is
}
} while (1);
- __SetPageLocked(new_page);
+ __SetPageLocked(hpage);
if (is_shmem)
- __SetPageSwapBacked(new_page);
- new_page->index = start;
- new_page->mapping = mapping;
+ __SetPageSwapBacked(hpage);
+ hpage->index = start;
+ hpage->mapping = mapping;
/*
- * At this point the new_page is locked and not up-to-date.
+ * At this point the hpage is locked and not up-to-date.
* It's safe to insert it into the page cache, because nobody would
* be able to map it or use it in another way until we unlock it.
*/
result = SCAN_FAIL;
goto xa_locked;
}
- xas_store(&xas, new_page);
+ xas_store(&xas, hpage);
nr_none++;
continue;
}
if (xa_is_value(page) || !PageUptodate(page)) {
+ struct folio *folio;
+
xas_unlock_irq(&xas);
/* swap in or instantiate fallocated page */
- if (shmem_getpage(mapping->host, index, &page,
- SGP_NOALLOC)) {
+ if (shmem_get_folio(mapping->host, index,
+ &folio, SGP_NOALLOC)) {
result = SCAN_FAIL;
goto xa_unlocked;
}
+ page = folio_file_page(folio, index);
} else if (trylock_page(page)) {
get_page(page);
xas_unlock_irq(&xas);
/*
* If file was truncated then extended, or hole-punched, before
* we locked the first page, then a THP might be there already.
+ * This will be discovered on the first iteration.
*/
if (PageTransCompound(page)) {
- result = SCAN_PAGE_COMPOUND;
+ struct page *head = compound_head(page);
+
+ result = compound_order(head) == HPAGE_PMD_ORDER &&
+ head->index == start
+ /* Maybe PMD-mapped */
+ ? SCAN_PTE_MAPPED_HUGEPAGE
+ : SCAN_PAGE_COMPOUND;
goto out_unlock;
}
list_add_tail(&page->lru, &pagelist);
/* Finally, replace with the new page. */
- xas_store(&xas, new_page);
+ xas_store(&xas, hpage);
continue;
out_unlock:
unlock_page(page);
put_page(page);
goto xa_unlocked;
}
- nr = thp_nr_pages(new_page);
+ nr = thp_nr_pages(hpage);
if (is_shmem)
- __mod_lruvec_page_state(new_page, NR_SHMEM_THPS, nr);
+ __mod_lruvec_page_state(hpage, NR_SHMEM_THPS, nr);
else {
- __mod_lruvec_page_state(new_page, NR_FILE_THPS, nr);
+ __mod_lruvec_page_state(hpage, NR_FILE_THPS, nr);
filemap_nr_thps_inc(mapping);
/*
* Paired with smp_mb() in do_dentry_open() to ensure
smp_mb();
if (inode_is_open_for_write(mapping->host)) {
result = SCAN_FAIL;
- __mod_lruvec_page_state(new_page, NR_FILE_THPS, -nr);
+ __mod_lruvec_page_state(hpage, NR_FILE_THPS, -nr);
filemap_nr_thps_dec(mapping);
goto xa_locked;
}
}
if (nr_none) {
- __mod_lruvec_page_state(new_page, NR_FILE_PAGES, nr_none);
+ __mod_lruvec_page_state(hpage, NR_FILE_PAGES, nr_none);
/* nr_none is always 0 for non-shmem. */
- __mod_lruvec_page_state(new_page, NR_SHMEM, nr_none);
+ __mod_lruvec_page_state(hpage, NR_SHMEM, nr_none);
}
/* Join all the small entries into a single multi-index entry */
xas_set_order(&xas, start, HPAGE_PMD_ORDER);
- xas_store(&xas, new_page);
+ xas_store(&xas, hpage);
xa_locked:
xas_unlock_irq(&xas);
xa_unlocked:
index = start;
list_for_each_entry_safe(page, tmp, &pagelist, lru) {
while (index < page->index) {
- clear_highpage(new_page + (index % HPAGE_PMD_NR));
+ clear_highpage(hpage + (index % HPAGE_PMD_NR));
index++;
}
- copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
- page);
+ copy_highpage(hpage + (page->index % HPAGE_PMD_NR),
+ page);
list_del(&page->lru);
page->mapping = NULL;
page_ref_unfreeze(page, 1);
index++;
}
while (index < end) {
- clear_highpage(new_page + (index % HPAGE_PMD_NR));
+ clear_highpage(hpage + (index % HPAGE_PMD_NR));
index++;
}
- SetPageUptodate(new_page);
- page_ref_add(new_page, HPAGE_PMD_NR - 1);
+ SetPageUptodate(hpage);
+ page_ref_add(hpage, HPAGE_PMD_NR - 1);
if (is_shmem)
- set_page_dirty(new_page);
- lru_cache_add(new_page);
+ set_page_dirty(hpage);
+ lru_cache_add(hpage);
/*
* Remove pte page tables, so we can re-fault the page as huge.
*/
- retract_page_tables(mapping, start);
- *hpage = NULL;
-
- khugepaged_pages_collapsed++;
+ result = retract_page_tables(mapping, start, mm, addr, hpage,
+ cc);
+ unlock_page(hpage);
+ hpage = NULL;
} else {
struct page *page;
VM_BUG_ON(nr_none);
xas_unlock_irq(&xas);
- new_page->mapping = NULL;
+ hpage->mapping = NULL;
}
- unlock_page(new_page);
+ if (hpage)
+ unlock_page(hpage);
out:
VM_BUG_ON(!list_empty(&pagelist));
- if (!IS_ERR_OR_NULL(*hpage))
- mem_cgroup_uncharge(page_folio(*hpage));
+ if (hpage) {
+ mem_cgroup_uncharge(page_folio(hpage));
+ put_page(hpage);
+ }
/* TODO: tracepoints */
+ return result;
}
-static void khugepaged_scan_file(struct mm_struct *mm,
- struct file *file, pgoff_t start, struct page **hpage)
+static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
+ struct file *file, pgoff_t start,
+ struct collapse_control *cc)
{
struct page *page = NULL;
struct address_space *mapping = file->f_mapping;
present = 0;
swap = 0;
- memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
+ memset(cc->node_load, 0, sizeof(cc->node_load));
rcu_read_lock();
xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {
if (xas_retry(&xas, page))
continue;
if (xa_is_value(page)) {
- if (++swap > khugepaged_max_ptes_swap) {
+ ++swap;
+ if (cc->is_khugepaged &&
+ swap > khugepaged_max_ptes_swap) {
result = SCAN_EXCEED_SWAP_PTE;
count_vm_event(THP_SCAN_EXCEED_SWAP_PTE);
break;
}
/*
- * XXX: khugepaged should compact smaller compound pages
+ * TODO: khugepaged should compact smaller compound pages
* into a PMD sized page
*/
if (PageTransCompound(page)) {
- result = SCAN_PAGE_COMPOUND;
+ struct page *head = compound_head(page);
+
+ result = compound_order(head) == HPAGE_PMD_ORDER &&
+ head->index == start
+ /* Maybe PMD-mapped */
+ ? SCAN_PTE_MAPPED_HUGEPAGE
+ : SCAN_PAGE_COMPOUND;
+ /*
+ * For SCAN_PTE_MAPPED_HUGEPAGE, further processing
+ * by the caller won't touch the page cache, and so
+ * it's safe to skip LRU and refcount checks before
+ * returning.
+ */
break;
}
node = page_to_nid(page);
- if (khugepaged_scan_abort(node)) {
+ if (hpage_collapse_scan_abort(node, cc)) {
result = SCAN_SCAN_ABORT;
break;
}
- khugepaged_node_load[node]++;
+ cc->node_load[node]++;
if (!PageLRU(page)) {
result = SCAN_PAGE_LRU;
rcu_read_unlock();
if (result == SCAN_SUCCEED) {
- if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) {
+ if (cc->is_khugepaged &&
+ present < HPAGE_PMD_NR - khugepaged_max_ptes_none) {
result = SCAN_EXCEED_NONE_PTE;
count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
} else {
- node = khugepaged_find_target_node();
- collapse_file(mm, file, start, hpage, node);
+ result = collapse_file(mm, addr, file, start, cc);
}
}
- /* TODO: tracepoints */
+ trace_mm_khugepaged_scan_file(mm, page, file->f_path.dentry->d_iname,
+ present, swap, result);
+ return result;
}
#else
-static void khugepaged_scan_file(struct mm_struct *mm,
- struct file *file, pgoff_t start, struct page **hpage)
+static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
+ struct file *file, pgoff_t start,
+ struct collapse_control *cc)
{
BUILD_BUG();
}
-static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot)
+static void khugepaged_collapse_pte_mapped_thps(struct khugepaged_mm_slot *mm_slot)
{
}
+
+static bool khugepaged_add_pte_mapped_thp(struct mm_struct *mm,
+ unsigned long addr)
+{
+ return false;
+}
#endif
-static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
- struct page **hpage)
+static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
+ struct collapse_control *cc)
__releases(&khugepaged_mm_lock)
__acquires(&khugepaged_mm_lock)
{
- struct mm_slot *mm_slot;
+ struct vma_iterator vmi;
+ struct khugepaged_mm_slot *mm_slot;
+ struct mm_slot *slot;
struct mm_struct *mm;
struct vm_area_struct *vma;
int progress = 0;
VM_BUG_ON(!pages);
lockdep_assert_held(&khugepaged_mm_lock);
+ *result = SCAN_FAIL;
- if (khugepaged_scan.mm_slot)
+ if (khugepaged_scan.mm_slot) {
mm_slot = khugepaged_scan.mm_slot;
- else {
- mm_slot = list_entry(khugepaged_scan.mm_head.next,
+ slot = &mm_slot->slot;
+ } else {
+ slot = list_entry(khugepaged_scan.mm_head.next,
struct mm_slot, mm_node);
+ mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
khugepaged_scan.address = 0;
khugepaged_scan.mm_slot = mm_slot;
}
spin_unlock(&khugepaged_mm_lock);
khugepaged_collapse_pte_mapped_thps(mm_slot);
- mm = mm_slot->mm;
+ mm = slot->mm;
/*
* Don't wait for semaphore (to avoid long wait times). Just move to
* the next mm on the list.
vma = NULL;
if (unlikely(!mmap_read_trylock(mm)))
goto breakouterloop_mmap_lock;
- if (likely(!khugepaged_test_exit(mm)))
- vma = find_vma(mm, khugepaged_scan.address);
progress++;
- for (; vma; vma = vma->vm_next) {
+ if (unlikely(hpage_collapse_test_exit(mm)))
+ goto breakouterloop;
+
+ vma_iter_init(&vmi, mm, khugepaged_scan.address);
+ for_each_vma(vmi, vma) {
unsigned long hstart, hend;
cond_resched();
- if (unlikely(khugepaged_test_exit(mm))) {
+ if (unlikely(hpage_collapse_test_exit(mm))) {
progress++;
break;
}
- if (!hugepage_vma_check(vma, vma->vm_flags, false, false)) {
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false, true)) {
skip:
progress++;
continue;
VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
while (khugepaged_scan.address < hend) {
- int ret;
+ bool mmap_locked = true;
+
cond_resched();
- if (unlikely(khugepaged_test_exit(mm)))
+ if (unlikely(hpage_collapse_test_exit(mm)))
goto breakouterloop;
VM_BUG_ON(khugepaged_scan.address < hstart ||
khugepaged_scan.address);
mmap_read_unlock(mm);
- ret = 1;
- khugepaged_scan_file(mm, file, pgoff, hpage);
+ *result = hpage_collapse_scan_file(mm,
+ khugepaged_scan.address,
+ file, pgoff, cc);
+ mmap_locked = false;
fput(file);
} else {
- ret = khugepaged_scan_pmd(mm, vma,
- khugepaged_scan.address,
- hpage);
+ *result = hpage_collapse_scan_pmd(mm, vma,
+ khugepaged_scan.address,
+ &mmap_locked,
+ cc);
+ }
+ switch (*result) {
+ case SCAN_PTE_MAPPED_HUGEPAGE: {
+ pmd_t *pmd;
+
+ *result = find_pmd_or_thp_or_none(mm,
+ khugepaged_scan.address,
+ &pmd);
+ if (*result != SCAN_SUCCEED)
+ break;
+ if (!khugepaged_add_pte_mapped_thp(mm,
+ khugepaged_scan.address))
+ break;
+ } fallthrough;
+ case SCAN_SUCCEED:
+ ++khugepaged_pages_collapsed;
+ break;
+ default:
+ break;
}
+
/* move to next address */
khugepaged_scan.address += HPAGE_PMD_SIZE;
progress += HPAGE_PMD_NR;
- if (ret)
- /* we released mmap_lock so break loop */
+ if (!mmap_locked)
+ /*
+ * We released mmap_lock so break loop. Note
+ * that we drop mmap_lock before all hugepage
+ * allocations, so if allocation fails, we are
+ * guaranteed to break here and report the
+ * correct result back to caller.
+ */
goto breakouterloop_mmap_lock;
if (progress >= pages)
goto breakouterloop;
* Release the current mm_slot if this mm is about to die, or
* if we scanned all vmas of this mm.
*/
- if (khugepaged_test_exit(mm) || !vma) {
+ if (hpage_collapse_test_exit(mm) || !vma) {
/*
* Make sure that if mm_users is reaching zero while
* khugepaged runs here, khugepaged_exit will find
* mm_slot not pointing to the exiting mm.
*/
- if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
- khugepaged_scan.mm_slot = list_entry(
- mm_slot->mm_node.next,
- struct mm_slot, mm_node);
+ if (slot->mm_node.next != &khugepaged_scan.mm_head) {
+ slot = list_entry(slot->mm_node.next,
+ struct mm_slot, mm_node);
+ khugepaged_scan.mm_slot =
+ mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
khugepaged_scan.address = 0;
} else {
khugepaged_scan.mm_slot = NULL;
kthread_should_stop();
}
-static void khugepaged_do_scan(void)
+static void khugepaged_do_scan(struct collapse_control *cc)
{
- struct page *hpage = NULL;
unsigned int progress = 0, pass_through_head = 0;
unsigned int pages = READ_ONCE(khugepaged_pages_to_scan);
bool wait = true;
+ int result = SCAN_SUCCEED;
lru_add_drain_all();
- while (progress < pages) {
- if (!khugepaged_prealloc_page(&hpage, &wait))
- break;
-
+ while (true) {
cond_resched();
if (unlikely(kthread_should_stop() || try_to_freeze()))
if (khugepaged_has_work() &&
pass_through_head < 2)
progress += khugepaged_scan_mm_slot(pages - progress,
- &hpage);
+ &result, cc);
else
progress = pages;
spin_unlock(&khugepaged_mm_lock);
- }
- if (!IS_ERR_OR_NULL(hpage))
- put_page(hpage);
+ if (progress >= pages)
+ break;
+
+ if (result == SCAN_ALLOC_HUGE_PAGE_FAIL) {
+ /*
+ * If fail to allocate the first time, try to sleep for
+ * a while. When hit again, cancel the scan.
+ */
+ if (!wait)
+ break;
+ wait = false;
+ khugepaged_alloc_sleep();
+ }
+ }
}
static bool khugepaged_should_wakeup(void)
static int khugepaged(void *none)
{
- struct mm_slot *mm_slot;
+ struct khugepaged_mm_slot *mm_slot;
set_freezable();
set_user_nice(current, MAX_NICE);
while (!kthread_should_stop()) {
- khugepaged_do_scan();
+ khugepaged_do_scan(&khugepaged_collapse_control);
khugepaged_wait_work();
}
set_recommended_min_free_kbytes();
mutex_unlock(&khugepaged_mutex);
}
+
+static int madvise_collapse_errno(enum scan_result r)
+{
+ /*
+ * MADV_COLLAPSE breaks from existing madvise(2) conventions to provide
+ * actionable feedback to caller, so they may take an appropriate
+ * fallback measure depending on the nature of the failure.
+ */
+ switch (r) {
+ case SCAN_ALLOC_HUGE_PAGE_FAIL:
+ return -ENOMEM;
+ case SCAN_CGROUP_CHARGE_FAIL:
+ return -EBUSY;
+ /* Resource temporary unavailable - trying again might succeed */
+ case SCAN_PAGE_LOCK:
+ case SCAN_PAGE_LRU:
+ case SCAN_DEL_PAGE_LRU:
+ return -EAGAIN;
+ /*
+ * Other: Trying again likely not to succeed / error intrinsic to
+ * specified memory range. khugepaged likely won't be able to collapse
+ * either.
+ */
+ default:
+ return -EINVAL;
+ }
+}
+
+int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
+ unsigned long start, unsigned long end)
+{
+ struct collapse_control *cc;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long hstart, hend, addr;
+ int thps = 0, last_fail = SCAN_FAIL;
+ bool mmap_locked = true;
+
+ BUG_ON(vma->vm_start > start);
+ BUG_ON(vma->vm_end < end);
+
+ *prev = vma;
+
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false))
+ return -EINVAL;
+
+ cc = kmalloc(sizeof(*cc), GFP_KERNEL);
+ if (!cc)
+ return -ENOMEM;
+ cc->is_khugepaged = false;
+ cc->last_target_node = NUMA_NO_NODE;
+
+ mmgrab(mm);
+ lru_add_drain_all();
+
+ hstart = (start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+ hend = end & HPAGE_PMD_MASK;
+
+ for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) {
+ int result = SCAN_FAIL;
+
+ if (!mmap_locked) {
+ cond_resched();
+ mmap_read_lock(mm);
+ mmap_locked = true;
+ result = hugepage_vma_revalidate(mm, addr, false, &vma,
+ cc);
+ if (result != SCAN_SUCCEED) {
+ last_fail = result;
+ goto out_nolock;
+ }
+
+ hend = vma->vm_end & HPAGE_PMD_MASK;
+ }
+ mmap_assert_locked(mm);
+ memset(cc->node_load, 0, sizeof(cc->node_load));
+ if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) {
+ struct file *file = get_file(vma->vm_file);
+ pgoff_t pgoff = linear_page_index(vma, addr);
+
+ mmap_read_unlock(mm);
+ mmap_locked = false;
+ result = hpage_collapse_scan_file(mm, addr, file, pgoff,
+ cc);
+ fput(file);
+ } else {
+ result = hpage_collapse_scan_pmd(mm, vma, addr,
+ &mmap_locked, cc);
+ }
+ if (!mmap_locked)
+ *prev = NULL; /* Tell caller we dropped mmap_lock */
+
+handle_result:
+ switch (result) {
+ case SCAN_SUCCEED:
+ case SCAN_PMD_MAPPED:
+ ++thps;
+ break;
+ case SCAN_PTE_MAPPED_HUGEPAGE:
+ BUG_ON(mmap_locked);
+ BUG_ON(*prev);
+ mmap_write_lock(mm);
+ result = collapse_pte_mapped_thp(mm, addr, true);
+ mmap_write_unlock(mm);
+ goto handle_result;
+ /* Whitelisted set of results where continuing OK */
+ case SCAN_PMD_NULL:
+ case SCAN_PTE_NON_PRESENT:
+ case SCAN_PTE_UFFD_WP:
+ case SCAN_PAGE_RO:
+ case SCAN_LACK_REFERENCED_PAGE:
+ case SCAN_PAGE_NULL:
+ case SCAN_PAGE_COUNT:
+ case SCAN_PAGE_LOCK:
+ case SCAN_PAGE_COMPOUND:
+ case SCAN_PAGE_LRU:
+ case SCAN_DEL_PAGE_LRU:
+ last_fail = result;
+ break;
+ default:
+ last_fail = result;
+ /* Other error, exit */
+ goto out_maybelock;
+ }
+ }
+
+out_maybelock:
+ /* Caller expects us to hold mmap_lock on return */
+ if (!mmap_locked)
+ mmap_read_lock(mm);
+out_nolock:
+ mmap_assert_locked(mm);
+ mmdrop(mm);
+ kfree(cc);
+
+ return thps == ((hend - hstart) >> HPAGE_PMD_SHIFT) ? 0
+ : madvise_collapse_errno(last_fail);
+}
projects / platform / kernel / linux-starfive.git / blobdiff