diff options
| author | Hao Li <hao.li@linux.dev> | 2026-02-26 19:51:37 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-03-04 09:44:23 -0800 |
| commit | dccd5ee2625d50239510bcd73ed78559005e00a3 (patch) | |
| tree | 65ba1ed81a74cfbf0f420655c8ed1eb5e68c6f33 /mm | |
| parent | a1e59fc6ee4ed8988ea4aeb9224e75d03175be9c (diff) | |
memcg: fix slab accounting in refill_obj_stock() trylock path
In the trylock path of refill_obj_stock(), mod_objcg_mlstate() should use
the real alloc/free bytes (i.e., nr_acct) for accounting, rather than
nr_bytes.
The user-visible impact is that the NR_SLAB_RECLAIMABLE_B and
NR_SLAB_UNRECLAIMABLE_B stats can end up being incorrect.
For example, if a user allocates a 6144-byte object, then before this
fix efill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=2048), even
though it should account for 6144 bytes (i.e., nr_acct).
When the user later frees the same object with kfree(),
refill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=6144). This
ends up adding 6144 to the stats, but it should be applying -6144
(i.e., nr_acct) since the object is being freed.
Link: https://lkml.kernel.org/r/20260226115145.62903-1-hao.li@linux.dev
Fixes: 200577f69f29 ("memcg: objcg stock trylock without irq disabling")
Signed-off-by: Hao Li <hao.li@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a52da3a5e4fd..772bac21d155 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3086,7 +3086,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, if (!local_trylock(&obj_stock.lock)) { if (pgdat) - mod_objcg_mlstate(objcg, pgdat, idx, nr_bytes); + mod_objcg_mlstate(objcg, pgdat, idx, nr_acct); nr_pages = nr_bytes >> PAGE_SHIFT; nr_bytes = nr_bytes & (PAGE_SIZE - 1); atomic_add(nr_bytes, &objcg->nr_charged_bytes); |