diff options
| author | Harry Yoo <harry.yoo@oracle.com> | 2025-11-11 21:53:31 +0900 |
|---|---|---|
| committer | Vlastimil Babka <vbabka@suse.cz> | 2025-11-13 19:56:46 +0100 |
| commit | cbcff934fa7deb670d9545a3aad4d07e8f1e4f3c (patch) | |
| tree | af142ae6a12f456ed3bcc1b53cbe7d51f25028b4 /mm/slub.c | |
| parent | c379b745e12a99f0a54bafaaf75fc710614511ce (diff) | |
mm/slub: fix memory leak in free_to_pcs_bulk()
The commit 989b09b73978 ("slab: skip percpu sheaves for remote object
freeing") introduced the remote_objects array in free_to_pcs_bulk() to
skip sheaves when objects from a remote node are freed.
However, the array is flushed only when:
1) the array becomes full (++remote_nr >= PCS_BATCH_MAX), or
2) slab_free_hook() returns false and size becomes zero.
When neither of the conditions is met, objects in the array are leaked.
This resulted in a memory leak [1], where 82 GiB of memory was allocated
for the maple_node cache.
Flush the array after successfully freeing objects to sheaves
in the do_free: path.
In the meantime, move the snippet if (!size) goto flush_remote; outside
the while loop for readability. Let's say all objects in the array are
from a remote node: then we acquire s->cpu_sheaves->lock and try to free
an object even when size is zero. This doesn't appear to be harmful,
but isn't really readable.
Reported-by: Tytus Rogalewski <admin@simplepod.ai>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220765 [1]
Closes: https://lore.kernel.org/linux-mm/20251107094809.12e9d705b7bf4815783eb184@linux-foundation.org
Closes: https://lore.kernel.org/all/aRGDTwbt2EIz2CYn@hyeyoo
Fixes: 989b09b73978 ("slab: skip percpu sheaves for remote object freeing")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20251111125331.12246-1-harry.yoo@oracle.com
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Tested-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Tytus Rogalewski <admin@simplepod.ai>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/slub.c b/mm/slub.c index f1a5373eee7b..a787687a0d59 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -6332,8 +6332,6 @@ next_remote_batch: if (unlikely(!slab_free_hook(s, p[i], init, false))) { p[i] = p[--size]; - if (!size) - goto flush_remote; continue; } @@ -6348,6 +6346,9 @@ next_remote_batch: i++; } + if (!size) + goto flush_remote; + next_batch: if (!local_trylock(&s->cpu_sheaves->lock)) goto fallback; @@ -6402,6 +6403,9 @@ do_free: goto next_batch; } + if (remote_nr) + goto flush_remote; + return; no_empty: |