+ mm-vmalloc-take-vmap_purge_lock-in-shrinker.patch added to mm-hotfixes-unstable branch

Andrew Morton
2026-04-14T05:30:48Z

The patch titled
Subject: mm/vmalloc: take vmap_purge_lock in shrinker
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-vmalloc-take-vmap_purge_lock-in-shrinker.patch

This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmalloc-take-vmap_purge_lock-in-shrinker.patch

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

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------------------------------------------------------
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Subject: mm/vmalloc: take vmap_purge_lock in shrinker
Date: Mon, 13 Apr 2026 21:26:46 +0200

decay_va_pool_node() can be invoked concurrently from two paths:
__purge_vmap_area_lazy() when pools are being purged, and the shrinker via
vmap_node_shrink_scan().

However, decay_va_pool_node() is not safe to run concurrently, and the
shrinker path currently lacks serialization, leading to races and possible
leaks.

Protect decay_va_pool_node() by taking vmap_purge_lock in the shrinker
path to ensure serialization with purge users.

Link: https://lkml.kernel.org/r/20260413192646.14683-1-urezki@gmail.com
Fixes: 7679ba6b36db ("mm: vmalloc: add a shrinker to drain vmap pools")
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: chenyichong <chenyichong@uniontech.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/vmalloc.c | 1 +
1 file changed, 1 insertion(+)

--- a/mm/vmalloc.c~mm-vmalloc-take-vmap_purge_lock-in-shrinker
+++ a/mm/vmalloc.c
@@ -5416,6 +5416,7 @@ vmap_node_shrink_scan(struct shrinker *s
{
struct vmap_node *vn;

+ guard(mutex)(&vmap_purge_lock);
for_each_vmap_node(vn)
decay_va_pool_node(vn, true);

_

Patches currently in -mm which might be from urezki@gmail.com are

mm-vmalloc-take-vmap_purge_lock-in-shrinker.patch