Re: [PATCH v5 2/8] mm/slab: handle the !allow_spin case in kfree_rcu_sheaf()

[hu.shengming]

Harry wrote:
> Teach kfree_rcu_sheaf() how to handle the !allow_spin case. Try to get
> an empty sheaf from pcs->spare or the barn even when spinning is not
> allowed. Unlike __pcs_replace_full_main(), try harder to allocate
> an empty sheaf because the fallback path will be more expensive than
> kfree_nolock().
> 
> Now that slab has internal alloc_flags to describe context, introduce
> free_flags analogously and convert free_flags to alloc_flags when
> allocating memory in the free path.
> 
> When trylock fails or the kernel observes non-NULL pcs->rcu_free after
> lock acquisition, free the sheaf instead of putting it to the barn.
> This is rare and not worth complicating the code.
> 
> Since call_rcu() cannot be called in an unknown context,
> kfree_rcu_sheaf() fails when the rcu sheaf becomes full.
> 
> Link: https://lore.kernel.org/linux-mm/872bd673-3d45-4111-8a41-31185db3ece5@xxxxxxxxxx
> Reviewed-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>
> Signed-off-by: Harry Yoo (Oracle) <harry@xxxxxxxxxx>


LGTM!
Reviewed-by: Shengming Hu <hu.shengming@xxxxxxxxxx>

--
With Best Regards,
Shengming