return true;
}
+static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int new_order,
+ struct page *split_at, struct xa_state *xas,
+ struct address_space *mapping, bool do_lru,
+ struct list_head *list, enum split_type split_type,
+ pgoff_t end, int *nr_shmem_dropped, int extra_pins)
+{
+ struct folio *end_folio = folio_next(folio);
+ struct folio *new_folio, *next;
+ int old_order = folio_order(folio);
+ int ret = 0;
+ struct deferred_split *ds_queue;
+
+ VM_WARN_ON_ONCE(!mapping && end);
+ /* Prevent deferred_split_scan() touching ->_refcount */
+ ds_queue = folio_split_queue_lock(folio);
+ if (folio_ref_freeze(folio, 1 + extra_pins)) {
+ struct swap_cluster_info *ci = NULL;
+ struct lruvec *lruvec;
+ int expected_refs;
+
+ if (old_order > 1) {
+ if (!list_empty(&folio->_deferred_list)) {
+ ds_queue->split_queue_len--;
+ /*
+ * Reinitialize page_deferred_list after removing the
+ * page from the split_queue, otherwise a subsequent
+ * split will see list corruption when checking the
+ * page_deferred_list.
+ */
+ list_del_init(&folio->_deferred_list);
+ }
+ if (folio_test_partially_mapped(folio)) {
+ folio_clear_partially_mapped(folio);
+ mod_mthp_stat(old_order,
+ MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1);
+ }
+ }
+ split_queue_unlock(ds_queue);
+ if (mapping) {
+ int nr = folio_nr_pages(folio);
+
+ if (folio_test_pmd_mappable(folio) &&
+ new_order < HPAGE_PMD_ORDER) {
+ if (folio_test_swapbacked(folio)) {
+ __lruvec_stat_mod_folio(folio,
+ NR_SHMEM_THPS, -nr);
+ } else {
+ __lruvec_stat_mod_folio(folio,
+ NR_FILE_THPS, -nr);
+ filemap_nr_thps_dec(mapping);
+ }
+ }
+ }
+
+ if (folio_test_swapcache(folio)) {
+ if (mapping) {
+ VM_WARN_ON_ONCE_FOLIO(mapping, folio);
+ return -EINVAL;
+ }
+
+ ci = swap_cluster_get_and_lock(folio);
+ }
+
+ /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
+ if (do_lru)
+ lruvec = folio_lruvec_lock(folio);
+
+ ret = __split_unmapped_folio(folio, new_order, split_at, xas,
+ mapping, split_type);
+
+ /*
+ * Unfreeze after-split folios and put them back to the right
+ * list. @folio should be kept frozon until page cache
+ * entries are updated with all the other after-split folios
+ * to prevent others seeing stale page cache entries.
+ * As a result, new_folio starts from the next folio of
+ * @folio.
+ */
+ for (new_folio = folio_next(folio); new_folio != end_folio;
+ new_folio = next) {
+ unsigned long nr_pages = folio_nr_pages(new_folio);
+
+ next = folio_next(new_folio);
+
+ zone_device_private_split_cb(folio, new_folio);
+
+ expected_refs = folio_expected_ref_count(new_folio) + 1;
+ folio_ref_unfreeze(new_folio, expected_refs);
+
+ if (do_lru)
+ lru_add_split_folio(folio, new_folio, lruvec, list);
+
+ /*
+ * Anonymous folio with swap cache.
+ * NOTE: shmem in swap cache is not supported yet.
+ */
+ if (ci) {
+ __swap_cache_replace_folio(ci, folio, new_folio);
+ continue;
+ }
+
+ /* Anonymous folio without swap cache */
+ if (!mapping)
+ continue;
+
+ /* Add the new folio to the page cache. */
+ if (new_folio->index < end) {
+ __xa_store(&mapping->i_pages, new_folio->index,
+ new_folio, 0);
+ continue;
+ }
+
+ VM_WARN_ON_ONCE(!nr_shmem_dropped);
+ /* Drop folio beyond EOF: ->index >= end */
+ if (shmem_mapping(mapping) && nr_shmem_dropped)
+ *nr_shmem_dropped += nr_pages;
+ else if (folio_test_clear_dirty(new_folio))
+ folio_account_cleaned(
+ new_folio, inode_to_wb(mapping->host));
+ __filemap_remove_folio(new_folio, NULL);
+ folio_put_refs(new_folio, nr_pages);
+ }
+
+ zone_device_private_split_cb(folio, NULL);
+ /*
+ * Unfreeze @folio only after all page cache entries, which
+ * used to point to it, have been updated with new folios.
+ * Otherwise, a parallel folio_try_get() can grab @folio
+ * and its caller can see stale page cache entries.
+ */
+ expected_refs = folio_expected_ref_count(folio) + 1;
+ folio_ref_unfreeze(folio, expected_refs);
+
+ if (do_lru)
+ unlock_page_lruvec(lruvec);
+
+ if (ci)
+ swap_cluster_unlock(ci);
+ } else {
+ split_queue_unlock(ds_queue);
+ return -EAGAIN;
+ }
+
+ return ret;
+}
+
/**
* __folio_split() - split a folio at @split_at to a @new_order folio
* @folio: folio to split
* @lock_at: a page within @folio to be left locked to caller
* @list: after-split folios will be put on it if non NULL
* @split_type: perform uniform split or not (non-uniform split)
- * @unmapped: The pages are already unmapped, they are migration entries.
*
* It calls __split_unmapped_folio() to perform uniform and non-uniform split.
* It is in charge of checking whether the split is supported or not and
*/
static int __folio_split(struct folio *folio, unsigned int new_order,
struct page *split_at, struct page *lock_at,
- struct list_head *list, enum split_type split_type, bool unmapped)
+ struct list_head *list, enum split_type split_type)
{
- struct deferred_split *ds_queue;
XA_STATE(xas, &folio->mapping->i_pages, folio->index);
struct folio *end_folio = folio_next(folio);
bool is_anon = folio_test_anon(folio);
int nr_shmem_dropped = 0;
int remap_flags = 0;
int extra_pins, ret;
- pgoff_t end;
+ pgoff_t end = 0;
bool is_hzp;
VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
* is taken to serialise against parallel split or collapse
* operations.
*/
- if (!unmapped) {
- anon_vma = folio_get_anon_vma(folio);
- if (!anon_vma) {
- ret = -EBUSY;
- goto out;
- }
- anon_vma_lock_write(anon_vma);
+ anon_vma = folio_get_anon_vma(folio);
+ if (!anon_vma) {
+ ret = -EBUSY;
+ goto out;
}
+ anon_vma_lock_write(anon_vma);
mapping = NULL;
} else {
unsigned int min_order;
goto out_unlock;
}
- if (!unmapped)
- unmap_folio(folio);
+ unmap_folio(folio);
/* block interrupt reentry in xa_lock and spinlock */
local_irq_disable();
}
}
- /* Prevent deferred_split_scan() touching ->_refcount */
- ds_queue = folio_split_queue_lock(folio);
- if (folio_ref_freeze(folio, 1 + extra_pins)) {
- struct swap_cluster_info *ci = NULL;
- struct lruvec *lruvec;
- int expected_refs;
-
- if (old_order > 1) {
- if (!list_empty(&folio->_deferred_list)) {
- ds_queue->split_queue_len--;
- /*
- * Reinitialize page_deferred_list after removing the
- * page from the split_queue, otherwise a subsequent
- * split will see list corruption when checking the
- * page_deferred_list.
- */
- list_del_init(&folio->_deferred_list);
- }
- if (folio_test_partially_mapped(folio)) {
- folio_clear_partially_mapped(folio);
- mod_mthp_stat(old_order,
- MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1);
- }
- }
- split_queue_unlock(ds_queue);
- if (mapping) {
- int nr = folio_nr_pages(folio);
-
- if (folio_test_pmd_mappable(folio) &&
- new_order < HPAGE_PMD_ORDER) {
- if (folio_test_swapbacked(folio)) {
- __lruvec_stat_mod_folio(folio,
- NR_SHMEM_THPS, -nr);
- } else {
- __lruvec_stat_mod_folio(folio,
- NR_FILE_THPS, -nr);
- filemap_nr_thps_dec(mapping);
- }
- }
- }
-
- if (folio_test_swapcache(folio)) {
- if (mapping) {
- VM_WARN_ON_ONCE_FOLIO(mapping, folio);
- ret = -EINVAL;
- goto fail;
- }
-
- ci = swap_cluster_get_and_lock(folio);
- }
-
- /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
- lruvec = folio_lruvec_lock(folio);
-
- ret = __split_unmapped_folio(folio, new_order, split_at, &xas,
- mapping, split_type);
-
- /*
- * Unfreeze after-split folios and put them back to the right
- * list. @folio should be kept frozon until page cache
- * entries are updated with all the other after-split folios
- * to prevent others seeing stale page cache entries.
- * As a result, new_folio starts from the next folio of
- * @folio.
- */
- for (new_folio = folio_next(folio); new_folio != end_folio;
- new_folio = next) {
- unsigned long nr_pages = folio_nr_pages(new_folio);
-
- next = folio_next(new_folio);
-
- zone_device_private_split_cb(folio, new_folio);
-
- expected_refs = folio_expected_ref_count(new_folio) + 1;
- folio_ref_unfreeze(new_folio, expected_refs);
-
- if (!unmapped)
- lru_add_split_folio(folio, new_folio, lruvec, list);
-
- /*
- * Anonymous folio with swap cache.
- * NOTE: shmem in swap cache is not supported yet.
- */
- if (ci) {
- __swap_cache_replace_folio(ci, folio, new_folio);
- continue;
- }
-
- /* Anonymous folio without swap cache */
- if (!mapping)
- continue;
-
- /* Add the new folio to the page cache. */
- if (new_folio->index < end) {
- __xa_store(&mapping->i_pages, new_folio->index,
- new_folio, 0);
- continue;
- }
-
- /* Drop folio beyond EOF: ->index >= end */
- if (shmem_mapping(mapping))
- nr_shmem_dropped += nr_pages;
- else if (folio_test_clear_dirty(new_folio))
- folio_account_cleaned(
- new_folio, inode_to_wb(mapping->host));
- __filemap_remove_folio(new_folio, NULL);
- folio_put_refs(new_folio, nr_pages);
- }
-
- zone_device_private_split_cb(folio, NULL);
- /*
- * Unfreeze @folio only after all page cache entries, which
- * used to point to it, have been updated with new folios.
- * Otherwise, a parallel folio_try_get() can grab @folio
- * and its caller can see stale page cache entries.
- */
- expected_refs = folio_expected_ref_count(folio) + 1;
- folio_ref_unfreeze(folio, expected_refs);
-
- unlock_page_lruvec(lruvec);
-
- if (ci)
- swap_cluster_unlock(ci);
- } else {
- split_queue_unlock(ds_queue);
- ret = -EAGAIN;
- }
+ ret = __folio_freeze_and_split_unmapped(folio, new_order, split_at, &xas, mapping,
+ true, list, split_type, end, &nr_shmem_dropped,
+ extra_pins);
fail:
if (mapping)
xas_unlock(&xas);
local_irq_enable();
- if (unmapped)
- return ret;
-
if (nr_shmem_dropped)
shmem_uncharge(mapping->host, nr_shmem_dropped);
return ret;
}
+/**
+ * folio_split_unmapped() - split a large anon folio that is already unmapped
+ * @folio: folio to split
+ * @new_order: the order of folios after split
+ *
+ * This function is a helper for splitting folios that have already been
+ * unmapped. The use case is that the device or the CPU can refuse to migrate
+ * THP pages in the middle of migration, due to allocation issues on either
+ * side.
+ *
+ * anon_vma_lock is not required to be held, mmap_read_lock() or
+ * mmap_write_lock() should be held. @folio is expected to be locked by the
+ * caller. device-private and non device-private folios are supported along
+ * with folios that are in the swapcache. @folio should also be unmapped and
+ * isolated from LRU (if applicable)
+ *
+ * Upon return, the folio is not remapped, split folios are not added to LRU,
+ * free_folio_and_swap_cache() is not called, and new folios remain locked.
+ *
+ * Return: 0 on success, -EAGAIN if the folio cannot be split (e.g., due to
+ * insufficient reference count or extra pins).
+ */
+int folio_split_unmapped(struct folio *folio, unsigned int new_order)
+{
+ int extra_pins, ret = 0;
+
+ VM_WARN_ON_ONCE_FOLIO(folio_mapped(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(!folio_test_anon(folio), folio);
+
+ if (!can_split_folio(folio, 1, &extra_pins))
+ return -EAGAIN;
+
+ local_irq_disable();
+ ret = __folio_freeze_and_split_unmapped(folio, new_order, &folio->page, NULL,
+ NULL, false, NULL, SPLIT_TYPE_UNIFORM,
+ 0, NULL, extra_pins);
+ local_irq_enable();
+ return ret;
+}
+
/*
* This function splits a large folio into smaller folios of order @new_order.
* @page can point to any page of the large folio to split. The split operation
* with the folio. Splitting to order 0 is compatible with all folios.
*/
int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
- unsigned int new_order, bool unmapped)
+ unsigned int new_order)
{
struct folio *folio = page_folio(page);
return __folio_split(folio, new_order, &folio->page, page, list,
- SPLIT_TYPE_UNIFORM, unmapped);
+ SPLIT_TYPE_UNIFORM);
}
/**
struct page *split_at, struct list_head *list)
{
return __folio_split(folio, new_order, split_at, &folio->page, list,
- SPLIT_TYPE_NON_UNIFORM, false);
+ SPLIT_TYPE_NON_UNIFORM);
}
int min_order_for_split(struct folio *folio)
projects / thirdparty / kernel / linux.git / commitdiff
