mm: memcontrol: correct the type of stats_updates to unsigned long

Patch series "fix unexpected type conversions and potential overflows",
v3.

As Harry Yoo pointed out [1], in scenarios where massive state updates
occur (e.g., during the reparenting of LRU folios), the values passed to
memcg stat update functions can accumulate and exceed the upper limit of a
32-bit integer.

If the parameter types are not large enough (like 'int') or are handled
incorrectly, it can lead to severe truncation, potential overflow issues,
and unexpected type conversion bugs.

This series aims to address these issues by correcting the parameter types
in the relevant functions, and by fixing an implicit conversion bug in
memcg_state_val_in_pages().


This patch (of 3):

The memcg_rstat_updated() tracks updates for vmstats_percpu->state and
lruvec_stats_percpu->state.  Since these state values are of type long,
change the val parameter passed to memcg_rstat_updated() to long as well.

Correspondingly, change the type of stats_updates in struct
memcg_vmstats_percpu and struct memcg_vmstats from unsigned int and
atomic_t to unsigned long and atomic_long_t respectively to prevent
potential overflow when handling large state updates during the
reparenting of LRU folios.

Link: https://lore.kernel.org/cover.1774604356.git.zhengqi.arch@bytedance.com
Link: https://lore.kernel.org/a5b0b468e7b4fe5f26c50e36d5d016f16d92f98f.1774604356.git.zhengqi.arch@bytedance.com
Link: https://lore.kernel.org/all/acDxaEgnqPI-Z4be@hyeyoo/ [1]
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions