From: Yeoreum Yun <yeoreum.yun@arm.com>
To: kasong@tencent.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>, Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R. Howlett" <liam@infradead.org>,
Nico Pache <nico.pache@linux.dev>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Lance Yang <lance.yang@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Chris Li <chrisl@kernel.org>,
Kemeng Shi <shikemeng@huaweicloud.com>,
Nhat Pham <nphamcs@gmail.com>, Baoquan He <baoquan.he@linux.dev>,
Barry Song <baohua@kernel.org>,
Youngjun Park <youngjun.park@lge.com>,
Yeoreum Yun <yeoreum.yun@arm.com>,
"Kiryl Shutsemau (Meta)" <kas@kernel.org>,
Shivam Kalra <shivamkalra98@zohomail.in>,
Kairui Song <ryncsn@gmail.com>
Subject: Re: [PATCH v5 11/17] mm/huge_memory: move filemap management into the file split helper
Date: Mon, 14 Sep 2026 18:30:07 +0100 [thread overview]
Message-ID: <aqgvHycVfCFI1FER@e129823.arm.com> (raw)
In-Reply-To: <20260915-swap-thp-cleanup-v5-11-39878b37dfb0@tencent.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
On Tue, Sep 15, 2026 at 01:14:52AM +0800, Kairui Song via B4 Relay wrote:
> From: Kairui Song <kasong@tencent.com>
>
> Only file split needs the filemap and xarray handling and related
> variables. Move them out of __folio_split() into the file helper so
> the helper is self-contained, and simplify the parameters.
>
> No functional change.
>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
> Signed-off-by: Kairui Song <kasong@tencent.com>
> ---
> mm/huge_memory.c | 102 ++++++++++++++++++++++++-------------------------------
> 1 file changed, 44 insertions(+), 58 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 859aefda7356..8fc1dd5b8354 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -4107,16 +4107,42 @@ static int __folio_freeze_split_anon(struct folio *folio,
>
> static int __folio_freeze_split_file(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)
> {
> + struct address_space *mapping = folio->mapping;
> + XA_STATE(xas, &mapping->i_pages, folio->index);
> struct folio *end_folio = folio_next(folio);
> struct folio *new_folio, *next;
> int nr_shmem_dropped = 0;
> + unsigned int min_order;
> struct lruvec *lruvec;
> pgoff_t end;
> - int ret;
> + gfp_t gfp;
> + int ret = 0;
> +
> + min_order = mapping_min_folio_order(mapping);
> + if (new_order < min_order)
> + return -EINVAL;
> +
> + gfp = current_gfp_context(mapping_gfp_mask(mapping) & GFP_RECLAIM_MASK);
> + if (!filemap_release_folio(folio, gfp))
> + return -EBUSY;
> +
> + mapping_set_update(&xas, mapping);
> +
> + if (split_type == SPLIT_TYPE_UNIFORM) {
> + int old_order = folio_order(folio);
> +
> + xas_set_order(&xas, folio->index, new_order);
> + xas_split_alloc(&xas, folio, old_order, gfp);
> + if (xas_error(&xas)) {
> + ret = xas_error(&xas);
> + goto fail_free;
> + }
> + }
> +
> + i_mmap_lock_read(mapping);
>
> /* Currently device private folios can only back anonymous memory. */
> VM_WARN_ON_ONCE_FOLIO(folio_is_device_private(folio), folio);
> @@ -4134,15 +4160,15 @@ static int __folio_freeze_split_file(struct folio *folio,
>
> ret = unmap_folio(folio);
> if (ret)
> - return ret;
> + goto fail_mmap_unlock;
>
> - xas_lock_irq(xas);
> + xas_lock_irq(&xas);
>
> /*
> * Check if the folio is present in page cache.
> * We assume all tail are present too, if folio is there.
> */
> - if (xas_load(xas) != folio) {
> + if (xas_load(&xas) != folio) {
> ret = -EAGAIN;
> goto fail;
> }
> @@ -4169,7 +4195,7 @@ static int __folio_freeze_split_file(struct folio *folio,
> if (do_lru)
> lruvec = folio_lruvec_lock(folio);
>
> - ret = __split_frozen_folio(folio, new_order, split_at, xas,
> + ret = __split_frozen_folio(folio, new_order, split_at, &xas,
> mapping, split_type);
>
> /*
> @@ -4225,9 +4251,19 @@ static int __folio_freeze_split_file(struct folio *folio,
> * If we want to use try_to_migrate() on file in unmap_folio,
> * remember to add remap_anon_folio() and adapt it.
> */
> - xas_unlock_irq(xas);
> + xas_unlock_irq(&xas);
> +fail_mmap_unlock:
> if (nr_shmem_dropped)
> shmem_uncharge(mapping->host, nr_shmem_dropped);
> + /*
> + * Drop the mapping while the inode is still pinned. @folio stays
> + * locked and present in the page cache, so eviction cannot free
> + * the inode yet, nothing past this point may touch the inode or
> + * the mapping.
> + */
> + i_mmap_unlock_read(mapping);
> +fail_free:
> + xas_destroy(&xas);
> return ret;
> }
>
> @@ -4256,11 +4292,9 @@ 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)
> {
> - XA_STATE(xas, &folio->mapping->i_pages, folio->index);
> struct folio *end_folio = folio_next(folio);
> bool is_anon = folio_test_anon(folio);
> struct mem_cgroup *memcg, *old_memcg;
> - struct address_space *mapping = NULL;
> struct anon_vma *anon_vma = NULL;
> int old_order = folio_order(folio);
> struct folio *new_folio, *next;
> @@ -4307,60 +4341,15 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
> goto out;
> }
> anon_vma_lock_write(anon_vma);
> - mapping = NULL;
> - } else {
> - unsigned int min_order;
> - gfp_t gfp;
> -
> - mapping = folio->mapping;
> - min_order = mapping_min_folio_order(mapping);
> - if (new_order < min_order) {
> - ret = -EINVAL;
> - goto out;
> - }
> -
> - gfp = current_gfp_context(mapping_gfp_mask(mapping) &
> - GFP_RECLAIM_MASK);
> -
> - if (!filemap_release_folio(folio, gfp)) {
> - ret = -EBUSY;
> - goto out;
> - }
> -
> - mapping_set_update(&xas, mapping);
> -
> - if (split_type == SPLIT_TYPE_UNIFORM) {
> - xas_set_order(&xas, folio->index, new_order);
> - xas_split_alloc(&xas, folio, old_order, gfp);
> - if (xas_error(&xas)) {
> - ret = xas_error(&xas);
> - goto out;
> - }
> - }
> -
> - anon_vma = NULL;
> - i_mmap_lock_read(mapping);
> }
>
> if (is_anon)
> ret = __folio_freeze_split_anon(folio, new_order, split_at,
> true, list, split_type);
> else
> - ret = __folio_freeze_split_file(folio, new_order, split_at, &xas, mapping,
> + ret = __folio_freeze_split_file(folio, new_order, split_at,
> true, list, split_type);
>
> - /*
> - * Drop the mapping while the inode is still pinned. @folio stays
> - * locked and present in the page cache until the loop below, so
> - * eviction cannot free the inode yet; @lock_at is not enough, it may
> - * be a tail beyond EOF that the split already dropped from the page
> - * cache. Nothing past this point may touch the inode or the mapping.
> - */
> - if (mapping) {
> - i_mmap_unlock_read(mapping);
> - mapping = NULL;
> - }
> -
> /*
> * Unlock all after-split folios except the one containing
> * @lock_at page. If @folio is not split, it will be kept locked.
> @@ -4384,14 +4373,11 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
> anon_vma_unlock_write(anon_vma);
> put_anon_vma(anon_vma);
> }
> - if (mapping)
> - i_mmap_unlock_read(mapping);
> out:
> /* restore to caller's old_memcg */
> set_active_memcg(old_memcg);
> mem_cgroup_put(memcg);
> out_no_memcg:
> - xas_destroy(&xas);
> if (is_pmd_order(old_order))
> count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
> count_mthp_stat(old_order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED);
>
> --
> 2.55.0
>
>
--
Sincerely,
Yeoreum Yun
next prev parent reply other threads:[~2026-09-14 17:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-14 17:14 [PATCH v5 00/17] mm/huge_memory: clean up and decouple the anon and file split helpers Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 01/17] mm/swap: fix off-by-one in swap cache replace sanity check Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 02/17] mm/huge_memory: fix rejection of swap cache folios with a mapping Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 03/17] mm/huge_memory: invert folio_ref_freeze() check to reduce indentation Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 04/17] mm/huge_memory: split the routine for splitting anon and file folio Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 05/17] mm/huge_memory: rename __split_unmapped_folio() to __split_frozen_folio() Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 06/17] mm/huge_memory: consolidate irq and locking for folio split Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 07/17] mm/huge_memory: move EOF trimming into the file split helper Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 08/17] mm/huge_memory: move unmap and remap into the split helpers Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 09/17] mm/huge_memory: rename remap_page() to remap_anon_folio() Kairui Song via B4 Relay
2026-09-14 17:28 ` Yeoreum Yun
2026-09-14 17:14 ` [PATCH v5 10/17] mm/huge_memory: move the racy refcount check into unmap_folio() Kairui Song via B4 Relay
2026-09-14 17:29 ` Yeoreum Yun
2026-09-14 17:14 ` [PATCH v5 11/17] mm/huge_memory: move filemap management into the file split helper Kairui Song via B4 Relay
2026-09-14 17:30 ` Yeoreum Yun [this message]
2026-09-14 17:14 ` [PATCH v5 12/17] mm/huge_memory: move anon_vma handling into the anon " Kairui Song via B4 Relay
2026-09-14 17:27 ` Yeoreum Yun
2026-09-14 17:14 ` [PATCH v5 13/17] mm/huge_memory: move memcg switch into the file " Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 14/17] mm/huge_memory: drop the unused do_lru argument of " Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 15/17] mm/huge_memory: clean up after-split folio freeing in __folio_split Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 16/17] mm/huge_memory: count only swap cache refs in anon folio split Kairui Song via B4 Relay
2026-09-14 17:14 ` [PATCH v5 17/17] mm/huge_memory: drop the redundant mapping argument of __split_frozen_folio Kairui Song via B4 Relay
2026-09-15 0:45 ` [PATCH v5 00/17] mm/huge_memory: clean up and decouple the anon and file split helpers Andrew Morton
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