FAILED: patch "[PATCH] mm/vmalloc: take vmap_purge_lock in shrinker" failed to apply to 6.12-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x ec05f51f1e65bce95528543eb73fda56fd201d94
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026050349-operation-curled-2359@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ec05f51f1e65bce95528543eb73fda56fd201d94 Mon Sep 17 00:00:00 2001
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Date: Mon, 13 Apr 2026 21:26:46 +0200
Subject: [PATCH] mm/vmalloc: take vmap_purge_lock in shrinker

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://lore.kernel.org/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>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Cc: chenyichong <chenyichong@uniontech.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 61caa55a4402..676851d5cfe7 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -5416,6 +5416,7 @@ vmap_node_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 {
 	struct vmap_node *vn;
 
+	guard(mutex)(&vmap_purge_lock);
 	for_each_vmap_node(vn)
 		decay_va_pool_node(vn, true);