FAILED: patch "[PATCH] irqchip/gic-v2m: Prevent use after free of" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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 <[email protected]>.

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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 3318dc299b072a0511d6dfd8367f3304fb6d9827
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025042840-primer-repeater-2b77@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 3318dc299b072a0511d6dfd8367f3304fb6d9827 Mon Sep 17 00:00:00 2001
From: Suzuki K Poulose <[email protected]>
Date: Tue, 22 Apr 2025 17:16:16 +0100
Subject: [PATCH] irqchip/gic-v2m: Prevent use after free of
gicv2m_get_fwnode()

With ACPI in place, gicv2m_get_fwnode() is registered with the pci subsystem as pci_msi_get_fwnode_cb(), which may get invoked at runtime during a PCI host bridge probe. But, the call back is wrongly marked as __init, causing it to be freed, while being registered with the PCI subsystem and could trigger:

 Unable to handle kernel paging request at virtual address ffff8000816c0400
  gicv2m_get_fwnode+0x0/0x58 (P)
  pci_set_bus_msi_domain+0x74/0x88
  pci_register_host_bridge+0x194/0x548

This is easily reproducible on a Juno board with ACPI boot.

Retain the function for later use.

index c69894861866..dc98c39d2b20 100644
@@ -421,7 +421,7 @@ static int __init gicv2m_of_init(struct fwnode_handle *parent_handle,
 #ifdef CONFIG_ACPI
 static int acpi_num_msi;
 
-static __init struct fwnode_handle *gicv2m_get_fwnode(struct device *dev)
+static struct fwnode_handle *gicv2m_get_fwnode(struct device *dev)
 {
 	struct v2m_data *data;