Commit 391dc7f4 authored by Zi Yan's avatar Zi Yan Committed by Andrew Morton
Browse files

mm/huge_memory: deduplicate code in __folio_split() 

xas unlock, remap_page(), local_irq_enable() are moved out of if branches
to deduplicate the code.  While at it, add remap_flags to clean up
remap_page() call site.  nr_dropped is renamed to nr_shmem_dropped, as it
becomes a variable at __folio_split() scope.

Link: https://lkml.kernel.org/r/20250718183720.4054515-4-ziy@nvidia.com


Signed-off-by: default avatarZi Yan <ziy@nvidia.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Antonio Quartulli <antonio@mandelbit.com>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <k.shutemov@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3653fc1b

mm/huge_memory.c

+35 −38
Original line number Diff line number Diff line
@@ -3595,6 +3595,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order, 
	struct anon_vma *anon_vma = NULL;

	int order = folio_order(folio);

	struct folio *new_folio, *next;

	int nr_shmem_dropped = 0;

	int remap_flags = 0;

	int extra_pins, ret;

	pgoff_t end;

	bool is_hzp;
@@ -3718,15 +3720,16 @@ static int __folio_split(struct folio *folio, unsigned int new_order, 
		 */

		xas_lock(&xas);

		xas_reset(&xas);

		if (xas_load(&xas) != folio)

		if (xas_load(&xas) != folio) {

			ret = -EAGAIN;

			goto fail;

		}

	}



	/* 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 &&
@@ -3798,7 +3801,7 @@ static int __folio_split(struct folio *folio, unsigned int new_order, 
			/* 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);

					nr_shmem_dropped += folio_nr_pages(new_folio);

				else if (folio_test_clear_dirty(new_folio))

					folio_account_cleaned(

						new_folio,
@@ -3828,25 +3831,28 @@ static int __folio_split(struct folio *folio, unsigned int new_order, 


		if (swap_cache)

			xa_unlock(&swap_cache->i_pages);

	} else {

		spin_unlock(&ds_queue->split_queue_lock);

		ret = -EAGAIN;

	}

fail:

	if (mapping)

		xas_unlock(&xas);



	local_irq_enable();



		if (nr_dropped)

			shmem_uncharge(mapping->host, nr_dropped);

	if (nr_shmem_dropped)

		shmem_uncharge(mapping->host, nr_shmem_dropped);



		remap_page(folio, 1 << order,

			   !ret && folio_test_anon(folio) ?

				   RMP_USE_SHARED_ZEROPAGE :

				   0);

	if (!ret && is_anon)

		remap_flags = RMP_USE_SHARED_ZEROPAGE;

	remap_page(folio, 1 << order, remap_flags);



	/*

	 * 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) {

	for (new_folio = folio; new_folio != end_folio; new_folio = next) {

		next = folio_next(new_folio);

		if (new_folio == page_folio(lock_at))

			continue;
@@ -3861,15 +3867,6 @@ static int __folio_split(struct folio *folio, unsigned int new_order, 
		 */

		free_folio_and_swap_cache(new_folio);

	}

	} else {

		spin_unlock(&ds_queue->split_queue_lock);

fail:

		if (mapping)

			xas_unlock(&xas);

		local_irq_enable();

		remap_page(folio, folio_nr_pages(folio), 0);

		ret = -EAGAIN;

	}



out_unlock:

	if (anon_vma) {