On Tue, Feb 09, 2021 at 02:01:26PM -0500, Johannes Weiner wrote:

alloc_page_buffers() currently uses get_mem_cgroup_from_page() for
charging the buffers to the page owner, which does an rcu-protected
page->memcg lookup and acquires a reference. But buffer allocation has
the page lock held throughout, which pins the page to the memcg and
thereby the memcg - neither rcu nor holding an extra reference during
the allocation are necessary. Use a raw page_memcg() instead.

This was the last user of get_mem_cgroup_from_page(), delete it.

Reported-by: Muchun Song <redacted>
Signed-off-by: Johannes Weiner <redacted>

Acked-by: Roman Gushchin <redacted>

Thanks!