Re: [PATCH] mm/shmem: drop the second folio batch from shmem_undo_range()

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 11/12/26 11:39 AM, Qiliang Yuan wrote:
> shmem_undo_range() keeps a folio_batch and an array of FOLIO_BATCH_SIZE
> indices on its stack. Removing truncated folios from the page cache in
> batches added a second folio_batch to collect the folios to delete.
> 
> That grows the stack frame by about 200 bytes, past the 1024 byte limit
> of mips eyeq6_defconfig built with clang.
> 
> Pass fbatch itself to delete_from_page_cache_batch() once the swap
> entries are gone, as truncate_inode_pages_range() does. Undoing a failed
> fallocate() only removes the folios that are not uptodate, so remove
> those one at a time with truncate_inode_folio() as before.
> 
> Stack frame of shmem_undo_range() built with clang 18:
> 
>    config                before (bytes)  after (bytes)  change
>    mips eyeq6_defconfig             928            720    -22%
>    x86_64                           920            712    -23%
> 
> Fixes: b97fbd541ecba ("mm/shmem: remove truncated folios from the page cache in batches")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202611112032.TMyPU6Rm-lkp@intel.com/
> Signed-off-by: Qiliang Yuan <qiliang.yuan@linux.dev>
> ---
> David, this applies on top of b97fbd541ecba in shmem-7.5.misc; please
> fold it in if you prefer.
> ---

I think you should send out a complete v2, and David could queue your 
new version.