* order - 1 to new_order).
* @split_at: in buddy allocator like split, the folio containing @split_at
* will be split until its order becomes @new_order.
- * @lock_at: the folio containing @lock_at is left locked for caller.
- * @list: the after split folios will be added to @list if it is not NULL,
- * otherwise to LRU lists.
- * @end: the end of the file @folio maps to. -1 if @folio is anonymous memory.
* @xas: xa_state pointing to folio->mapping->i_pages and locked by caller
* @mapping: @folio->mapping
* @uniform_split: if the split is uniform or not (buddy allocator like split)
* @page, which is split in next for loop.
*
* After splitting, the caller's folio reference will be transferred to the
- * folio containing @page. The other folios may be freed if they are not mapped.
- *
- * In terms of locking, after splitting,
- * 1. uniform split leaves @page (or the folio contains it) locked;
- * 2. buddy allocator like (non-uniform) split leaves @folio locked.
- *
+ * folio containing @page. The caller needs to unlock and/or free after-split
+ * folios if necessary.
*
* For !uniform_split, when -ENOMEM is returned, the original folio might be
* split. The caller needs to check the input folio.
*/
static int __split_unmapped_folio(struct folio *folio, int new_order,
- struct page *split_at, struct page *lock_at,
- struct list_head *list, pgoff_t end,
- struct xa_state *xas, struct address_space *mapping,
- bool uniform_split)
+ struct page *split_at, struct xa_state *xas,
+ struct address_space *mapping, bool uniform_split)
{
- struct lruvec *lruvec;
- struct address_space *swap_cache = NULL;
- struct folio *origin_folio = folio;
- struct folio *next_folio = folio_next(folio);
- struct folio *new_folio;
- struct folio *next;
int order = folio_order(folio);
- int split_order;
int start_order = uniform_split ? new_order : order - 1;
- int nr_dropped = 0;
- int ret = 0;
bool stop_split = false;
-
- if (folio_test_swapcache(folio)) {
- VM_BUG_ON(mapping);
-
- /* a swapcache folio can only be uniformly split to order-0 */
- if (!uniform_split || new_order != 0)
- return -EINVAL;
-
- swap_cache = swap_address_space(folio->swap);
- xa_lock(&swap_cache->i_pages);
- }
+ struct folio *next;
+ int split_order;
+ int ret = 0;
if (folio_test_anon(folio))
mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
- /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
- lruvec = folio_lruvec_lock(folio);
-
folio_clear_has_hwpoisoned(folio);
/*
for (split_order = start_order;
split_order >= new_order && !stop_split;
split_order--) {
- int old_order = folio_order(folio);
- struct folio *release;
struct folio *end_folio = folio_next(folio);
+ int old_order = folio_order(folio);
+ struct folio *new_folio;
/* order-1 anonymous folio is not supported */
if (folio_test_anon(folio) && split_order == 1)
after_split:
/*
- * Iterate through after-split folios and perform related
- * operations. But in buddy allocator like split, the folio
+ * Iterate through after-split folios and update folio stats.
+ * But in buddy allocator like split, the folio
* containing the specified page is skipped until its order
* is new_order, since the folio will be worked on in next
* iteration.
*/
- for (release = folio; release != end_folio; release = next) {
- next = folio_next(release);
+ for (new_folio = folio; new_folio != end_folio; new_folio = next) {
+ next = folio_next(new_folio);
/*
- * for buddy allocator like split, the folio containing
- * page will be split next and should not be released,
- * until the folio's order is new_order or stop_split
- * is set to true by the above xas_split() failure.
+ * for buddy allocator like split, new_folio containing
+ * @split_at page could be split again, thus do not
+ * change stats yet. Wait until new_folio's order is
+ * @new_order or stop_split is set to true by the above
+ * xas_split() failure.
*/
- if (release == page_folio(split_at)) {
- folio = release;
+ if (new_folio == page_folio(split_at)) {
+ folio = new_folio;
if (split_order != new_order && !stop_split)
continue;
}
- if (folio_test_anon(release)) {
- mod_mthp_stat(folio_order(release),
- MTHP_STAT_NR_ANON, 1);
- }
-
- /*
- * origin_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.
- */
- if (release == origin_folio)
- continue;
-
- folio_ref_unfreeze(release, 1 +
- ((mapping || swap_cache) ?
- folio_nr_pages(release) : 0));
-
- lru_add_split_folio(origin_folio, release, lruvec,
- list);
-
- /* Some pages can be beyond EOF: drop them from cache */
- if (release->index >= end) {
- if (shmem_mapping(mapping))
- nr_dropped += folio_nr_pages(release);
- else if (folio_test_clear_dirty(release))
- folio_account_cleaned(release,
- inode_to_wb(mapping->host));
- __filemap_remove_folio(release, NULL);
- folio_put_refs(release, folio_nr_pages(release));
- } else if (mapping) {
- __xa_store(&mapping->i_pages,
- release->index, release, 0);
- } else if (swap_cache) {
- __xa_store(&swap_cache->i_pages,
- swap_cache_index(release->swap),
- release, 0);
- }
+ if (folio_test_anon(new_folio))
+ mod_mthp_stat(folio_order(new_folio),
+ MTHP_STAT_NR_ANON, 1);
}
}
- /*
- * Unfreeze origin_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 origin_folio and its caller can
- * see stale page cache entries.
- */
- folio_ref_unfreeze(origin_folio, 1 +
- ((mapping || swap_cache) ? folio_nr_pages(origin_folio) : 0));
-
- unlock_page_lruvec(lruvec);
-
- if (swap_cache)
- xa_unlock(&swap_cache->i_pages);
- if (mapping)
- xa_unlock(&mapping->i_pages);
-
- /* Caller disabled irqs, so they are still disabled here */
- local_irq_enable();
-
- if (nr_dropped)
- shmem_uncharge(mapping->host, nr_dropped);
-
- remap_page(origin_folio, 1 << order,
- folio_test_anon(origin_folio) ?
- RMP_USE_SHARED_ZEROPAGE : 0);
-
- /*
- * At this point, folio should contain the specified page.
- * For uniform split, it is left for caller to unlock.
- * For buddy allocator like split, the first after-split folio is left
- * for caller to unlock.
- */
- for (new_folio = origin_folio; new_folio != next_folio; new_folio = next) {
- next = folio_next(new_folio);
- if (new_folio == page_folio(lock_at))
- continue;
-
- folio_unlock(new_folio);
- /*
- * Subpages 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.
- */
- free_folio_and_swap_cache(new_folio);
- }
return ret;
}
* It is in charge of checking whether the split is supported or not and
* preparing @folio for __split_unmapped_folio().
*
+ * After splitting, the after-split folio containing @lock_at remains locked
+ * and others are unlocked:
+ * 1. for uniform split, @lock_at points to one of @folio's subpages;
+ * 2. for buddy allocator like (non-uniform) split, @lock_at points to @folio.
+ *
* return: 0: successful, <0 failed (if -ENOMEM is returned, @folio might be
* split but not to @new_order, the caller needs to check)
*/
{
struct deferred_split *ds_queue = get_deferred_split_queue(folio);
XA_STATE(xas, &folio->mapping->i_pages, folio->index);
+ struct folio *end_folio = folio_next(folio);
bool is_anon = folio_test_anon(folio);
struct address_space *mapping = NULL;
struct anon_vma *anon_vma = NULL;
int order = folio_order(folio);
+ struct folio *new_folio, *next;
int extra_pins, ret;
pgoff_t end;
bool is_hzp;
/* Prevent deferred_split_scan() touching ->_refcount */
spin_lock(&ds_queue->split_queue_lock);
if (folio_ref_freeze(folio, 1 + extra_pins)) {
+ struct address_space *swap_cache = NULL;
+ int nr_dropped = 0;
+ struct lruvec *lruvec;
+
if (folio_order(folio) > 1 &&
!list_empty(&folio->_deferred_list)) {
ds_queue->split_queue_len--;
}
}
- ret = __split_unmapped_folio(folio, new_order,
- split_at, lock_at, list, end, &xas, mapping,
- uniform_split);
+ if (folio_test_swapcache(folio)) {
+ VM_BUG_ON(mapping);
+
+ swap_cache = swap_address_space(folio->swap);
+ xa_lock(&swap_cache->i_pages);
+ }
+
+ /* 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, uniform_split);
+
+ /*
+ * 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) {
+ next = folio_next(new_folio);
+
+ folio_ref_unfreeze(
+ new_folio,
+ 1 + ((mapping || swap_cache) ?
+ folio_nr_pages(new_folio) :
+ 0));
+
+ lru_add_split_folio(folio, new_folio, lruvec, list);
+
+ /* Some pages can be beyond EOF: drop them from cache */
+ if (new_folio->index >= end) {
+ if (shmem_mapping(mapping))
+ nr_dropped += folio_nr_pages(new_folio);
+ 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,
+ folio_nr_pages(new_folio));
+ } else if (mapping) {
+ __xa_store(&mapping->i_pages, new_folio->index,
+ new_folio, 0);
+ } else if (swap_cache) {
+ __xa_store(&swap_cache->i_pages,
+ swap_cache_index(new_folio->swap),
+ new_folio, 0);
+ }
+ }
+ /*
+ * 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.
+ */
+ folio_ref_unfreeze(folio, 1 +
+ ((mapping || swap_cache) ? folio_nr_pages(folio) : 0));
+
+ unlock_page_lruvec(lruvec);
+
+ if (swap_cache)
+ xa_unlock(&swap_cache->i_pages);
+ if (mapping)
+ xas_unlock(&xas);
+
+ local_irq_enable();
+
+ if (nr_dropped)
+ shmem_uncharge(mapping->host, nr_dropped);
+
+ remap_page(folio, 1 << order,
+ !ret && folio_test_anon(folio) ?
+ RMP_USE_SHARED_ZEROPAGE :
+ 0);
+
+ /*
+ * Unlock all after-split folios except the one containing
+ * @lock_at page. If @folio is not split, it will be kept locked.
+ */
+ for (new_folio = folio; new_folio != end_folio;
+ new_folio = next) {
+ next = folio_next(new_folio);
+ if (new_folio == page_folio(lock_at))
+ continue;
+
+ folio_unlock(new_folio);
+ /*
+ * Subpages 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.
+ */
+ free_folio_and_swap_cache(new_folio);
+ }
} else {
spin_unlock(&ds_queue->split_queue_lock);
fail:
projects / thirdparty / kernel / linux.git / commitdiff
