The patch titled Subject: mm/mempolicy: fix memory leaks in weighted interleave sysfs has been added to the -mm mm-new branch. Its filename is mm-mempolicy-fix-memory-leaks-in-weighted-interleave-sysfs.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Rakie Kim rakie.kim@sk.com Subject: mm/mempolicy: fix memory leaks in weighted interleave sysfs Date: Wed, 16 Apr 2025 20:31:19 +0900

Patch series "Enhance sysfs handling for memory hotplug in weighted interleave", v8.

The following patch series enhances the weighted interleave policy in the memory management subsystem by improving sysfs handling, fixing memory leaks, and introducing dynamic sysfs updates for memory hotplug support.

This patch (of 3):

Memory leaks occurred when removing sysfs attributes for weighted interleave. Improper kobject deallocation led to unreleased memory when initialization failed or when nodes were removed.

This patch resolves the issue by replacing unnecessary `kfree()` calls with proper `kobject_del()` and `kobject_put()` sequences, ensuring correct teardown and preventing memory leaks.

By explicitly calling `kobject_del()` before `kobject_put()`, the release function is now invoked safely, and internal sysfs state is correctly cleaned up. This guarantees that the memory associated with the kobject is fully released and avoids resource leaks, thereby improving system stability.

Additionally, sysfs_remove_file() is no longer called from the release function to avoid accessing invalid sysfs state after kobject_del(). All attribute removals are now done before kobject_del(), preventing WARN_ON() in kernfs and ensuring safe and consistent cleanup of sysfs entries.

Link: https://lkml.kernel.org/r/20250416113123.629-1-rakie.kim@sk.com Link: https://lkml.kernel.org/r/20250416113123.629-2-rakie.kim@sk.com Fixes: dce41f5ae253 ("mm/mempolicy: implement the sysfs-based weighted_interleave interface") Signed-off-by: Rakie Kim rakie.kim@sk.com Reviewed-by: Gregory Price gourry@gourry.net Reviewed-by: Joshua Hahn joshua.hahnjy@gmail.com Reviewed-by: Jonathan Cameron Jonathan.Cameron@huawei.com Cc: Dan Williams dan.j.williams@intel.com Cc: David Hildenbrand david@redhat.com Cc: Honggyu Kim honggyu.kim@sk.com Cc: "Huang, Ying" ying.huang@linux.alibaba.com Cc: Oscar Salvador osalvador@suse.de Cc: Yunjeong Mun yunjeong.mun@sk.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/mempolicy.c | 111 +++++++++++++++++++++++++---------------------- 1 file changed, 61 insertions(+), 50 deletions(-)

--- a/mm/mempolicy.c~mm-mempolicy-fix-memory-leaks-in-weighted-interleave-sysfs +++ a/mm/mempolicy.c @@ -3463,8 +3463,8 @@ static ssize_t node_store(struct kobject

static struct iw_node_attr **node_attrs;

-static void sysfs_wi_node_release(struct iw_node_attr *node_attr, - struct kobject *parent) +static void sysfs_wi_node_delete(struct iw_node_attr *node_attr, + struct kobject *parent) { if (!node_attr) return; @@ -3473,18 +3473,41 @@ static void sysfs_wi_node_release(struct kfree(node_attr); }

-static void sysfs_wi_release(struct kobject *wi_kobj) +static void sysfs_wi_node_delete_all(struct kobject *wi_kobj) { - int i; + int nid;

- for (i = 0; i < nr_node_ids; i++) - sysfs_wi_node_release(node_attrs[i], wi_kobj); - kobject_put(wi_kobj); + for (nid = 0; nid < nr_node_ids; nid++) + sysfs_wi_node_delete(node_attrs[nid], wi_kobj); +} + +static void iw_table_free(void) +{ + u8 *old; + + mutex_lock(&iw_table_lock); + old = rcu_dereference_protected(iw_table, + lockdep_is_held(&iw_table_lock)); + if (old) { + rcu_assign_pointer(iw_table, NULL); + mutex_unlock(&iw_table_lock); + + synchronize_rcu(); + kfree(old); + } else + mutex_unlock(&iw_table_lock); +} + +static void wi_kobj_release(struct kobject *wi_kobj) +{ + iw_table_free(); + kfree(node_attrs); + kfree(wi_kobj); }

static const struct kobj_type wi_ktype = { .sysfs_ops = &kobj_sysfs_ops, - .release = sysfs_wi_release, + .release = wi_kobj_release, };

static int add_weight_node(int nid, struct kobject *wi_kobj) @@ -3525,41 +3548,42 @@ static int add_weighted_interleave_group struct kobject *wi_kobj; int nid, err;

+ node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *), + GFP_KERNEL); + if (!node_attrs) + return -ENOMEM; + wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL); - if (!wi_kobj) + if (!wi_kobj) { + kfree(node_attrs); return -ENOMEM; + }

err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj, "weighted_interleave"); - if (err) { - kfree(wi_kobj); - return err; - } + if (err) + goto err_put_kobj;

for_each_node_state(nid, N_POSSIBLE) { err = add_weight_node(nid, wi_kobj); if (err) { pr_err("failed to add sysfs [node%d]\n", nid); - break; + goto err_cleanup_kobj; } } - if (err) - kobject_put(wi_kobj); + return 0; + +err_cleanup_kobj: + sysfs_wi_node_delete_all(wi_kobj); + kobject_del(wi_kobj); +err_put_kobj: + kobject_put(wi_kobj); + return err; }

static void mempolicy_kobj_release(struct kobject *kobj) { - u8 *old; - - mutex_lock(&iw_table_lock); - old = rcu_dereference_protected(iw_table, - lockdep_is_held(&iw_table_lock)); - rcu_assign_pointer(iw_table, NULL); - mutex_unlock(&iw_table_lock); - synchronize_rcu(); - kfree(old); - kfree(node_attrs); kfree(kobj); }

@@ -3573,37 +3597,24 @@ static int __init mempolicy_sysfs_init(v static struct kobject *mempolicy_kobj;

mempolicy_kobj = kzalloc(sizeof(*mempolicy_kobj), GFP_KERNEL); - if (!mempolicy_kobj) { - err = -ENOMEM; - goto err_out; - } - - node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *), - GFP_KERNEL); - if (!node_attrs) { - err = -ENOMEM; - goto mempol_out; - } + if (!mempolicy_kobj) + return -ENOMEM;

err = kobject_init_and_add(mempolicy_kobj, &mempolicy_ktype, mm_kobj, "mempolicy"); if (err) - goto node_out; + goto err_put_kobj;

err = add_weighted_interleave_group(mempolicy_kobj); - if (err) { - pr_err("mempolicy sysfs structure failed to initialize\n"); - kobject_put(mempolicy_kobj); - return err; - } + if (err) + goto err_del_kobj;

- return err; -node_out: - kfree(node_attrs); -mempol_out: - kfree(mempolicy_kobj); -err_out: - pr_err("failed to add mempolicy kobject to the system\n"); + return 0; + +err_del_kobj: + kobject_del(mempolicy_kobj); +err_put_kobj: + kobject_put(mempolicy_kobj); return err; }

_

Patches currently in -mm which might be from rakie.kim@sk.com are

mm-mempolicy-fix-memory-leaks-in-weighted-interleave-sysfs.patch mm-mempolicy-prepare-weighted-interleave-sysfs-for-memory-hotplug.patch mm-mempolicy-support-memory-hotplug-in-weighted-interleave.patch