mm/huge_memory: consolidate irq and locking for folio split

Let each split helper handle its own locking instead of relying on the
caller, so both helpers manage their own irq and locking state.  This lets
__folio_split() drop its local irq handling and fail label, preparing for
further cleanup.

The file path now uses xas_lock_irq() instead of local_irq_disable() with
xas_lock().  The two are equivalent on non-RT, and TRANSPARENT_HUGEPAGE
cannot be enabled on RT anyway.  This conversion also buys consistency:
every other place in mm/ that freezes a folio while it is still reachable
through the page cache already takes the lock this way.  This was actually
the last plain xas_lock() on mapping->i_pages left in mm.  If we are going
to support RT, spinning on frozen folio refs could be a problem, but it
already exists in many places and should be fixed generically.

The anon helper keeps a single local_irq_disable() as before, because it
has to cover several plain spinlocks at once.

The dropped xas_reset() was a no-op as the xa_state is not walked before
the xas_load() under the lock.

Link: https://lore.kernel.org/20260923-swap-thp-cleanup-v6-6-ba1b4ba72c6f@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <nico.pache@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Shivam Kalra <shivamkalra98@zohomail.in>
Cc: Kairui Song <ryncsn@gmail.com>

0 files changed, 0 insertions, 0 deletions