Re: [PATCH 0/2] mm: fix memcg_data reads during a THP split

[Tao Yi <escape@deepseek.com>]

Hi Daejun,

Sorry, I missed your email on the RFC thread. Thanks for following up
and for taking care of the fix.

在 2026/11/4 17:59, Daejun Park via B4 Relay 写道:
> Tao Yi reported an oops in page_cgroup_ino() while reading
> /proc/kpagecgroup and traced it to the THP split in an RFC [1]. The
> RFC skips frozen folios in the reader. Patch 1 moves the memcg_data
> copy in the split instead. Patch 2 orders the same loads in
> page_owner and needs patch 1.
>
> Charged large kmalloc pages are frozen, so the RFC would report them
> as uncharged. My review of the RFC [2] got no reply. Tested on x86_64
> with KASAN, see patch 1.
>
> [1] https://lore.kernel.org/all/20260907124001.1544655-1-escape@deepseek.com/
> [2] https://lore.kernel.org/all/20261028040418epcms2p7ac0f584cdfdc6a0ea9b7f20eadeada3d@epcms2p7/
>
> ---
> Daejun Park (2):
>        mm/huge_memory: set memcg_data before a split page leaves the folio
>        mm/page_owner: also check PageTail before reading memcg_data
>
>   mm/huge_memory.c | 17 +++++++++++++----
>   mm/memcontrol.c  |  9 ++++++++-
>   mm/page_owner.c  |  7 +++++++
>   3 files changed, 28 insertions(+), 5 deletions(-)
> ---
> base-commit: a13b500946e5dc467976838572b8ddd2fd777ca7
> change-id: 20261028-kpagecgroup-split-8a749c6ee27e
>
> Best regards,