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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Yeoreum Yun , "Kiryl Shutsemau (Meta)" , Shivam Kalra , Kairui Song Subject: Re: [PATCH v5 11/17] mm/huge_memory: move filemap management into the file split helper Message-ID: References: <20260915-swap-thp-cleanup-v5-0-39878b37dfb0@tencent.com> <20260915-swap-thp-cleanup-v5-11-39878b37dfb0@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260915-swap-thp-cleanup-v5-11-39878b37dfb0@tencent.com> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: B028040017 X-Stat-Signature: hwbbaqki8sngtcmexekrnw4h83a6ytpy X-Rspam-User: X-HE-Tag: 1789407014-132506 X-HE-Meta: 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 eZR5c1c+ rBG9Ur+dSJpoGDDC9DVMA15m3jDOEs+m9NGCf/Cx2CqnwcVeNTf7AvpIfV3sapNNNuVhDaLocsWeZDx/2whC2GWXQ95FIL0C8XQdwETfP8Rs61JgpwHT1Es6EBwtSv3075RqcvzKqjv26DC9Uz/+TIbSJq0dAGy/3Kx1Yw4+7RDldyUDJAxSrY2V5jJleSZPaHBC4lJgo4VAlL/nMmd84TE+ve8sCtmEeye0fARoiwo8gBKpt/BEfCjwPmT41aRtLAydAVFNDPB+iQ7dB1QwJQXtqOSXZBwovFzIav2/d81THE/hQ/FHEEPDoBINvOH8kJkwAe5VB3jTZ/js1n0D1hTOwHcpxM7DtL01YoEC69HTNFoCwofZ1c/5huBptZshggxLMnXb1SuZaDjkR/g7lxd7VlWG/k5QjSjuz Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Reviewed-by: Yeoreum Yun On Tue, Sep 15, 2026 at 01:14:52AM +0800, Kairui Song via B4 Relay wrote: > From: Kairui Song > > 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 > Reviewed-by: Kiryl Shutsemau (Meta) > Signed-off-by: Kairui Song > --- > 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