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The commit989b09b739("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:989b09b739("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.