FAILED: patch "[PATCH] PCI: endpoint: pci-epf-vntb: Remove duplicate resource" 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 0da63230d3ec1ec5fcc443a2314233e95bfece54
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026042024-seldom-accuracy-953f@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 0da63230d3ec1ec5fcc443a2314233e95bfece54 Mon Sep 17 00:00:00 2001
From: Koichiro Den <[email protected]>
Date: Thu, 26 Feb 2026 17:41:38 +0900
Subject: [PATCH] PCI: endpoint: pci-epf-vntb: Remove duplicate resource
teardown

epf_ntb_epc_destroy() duplicates the teardown that the caller is supposed to perform later. This leads to an oops when .allow_link fails or when .drop_link is performed. The following is an example oops of the former case:

  Unable to handle kernel paging request at virtual address dead000000000108
  [...]
  [dead000000000108] address between user and kernel address ranges
  Internal error: Oops: 0000000096000044 [#1]  SMP
  [...]
  Call trace:
   pci_epc_remove_epf+0x78/0xe0 (P)
   pci_primary_epc_epf_link+0x88/0xa8
   configfs_symlink+0x1f4/0x5a0
   vfs_symlink+0x134/0x1d8
   do_symlinkat+0x88/0x138
   __arm64_sys_symlinkat+0x74/0xe0
  [...]

Remove the helper, and drop pci_epc_put(). EPC device refcounting is tied to the configfs EPC group lifetime, and pci_epc_put() in the .drop_link path is sufficient.

index 148a3b160812..42c870ee3956 100644
@@ -763,19 +763,6 @@ static void epf_ntb_mw_bar_clear(struct epf_ntb *ntb, int num_mws)
 	}
 }
 
-/**
- * epf_ntb_epc_destroy() - Cleanup NTB EPC interface
- * @ntb: NTB device that facilitates communication between HOST and VHOST
- *
- * Wrapper for epf_ntb_epc_destroy_interface() to cleanup all the NTB interfaces
- */
-static void epf_ntb_epc_destroy(struct epf_ntb *ntb)
-{
-	pci_epc_remove_epf(ntb->epf->epc, ntb->epf, 0);
-	pci_epc_put(ntb->epf->epc);
-}
-
-
 /**
  * epf_ntb_is_bar_used() - Check if a bar is used in the ntb configuration
  * @ntb: NTB device that facilitates communication between HOST and VHOST

@@ -1529,7 +1516,7 @@ static int epf_ntb_bind(struct pci_epf *epf)
 	ret = epf_ntb_init_epc_bar(ntb);
 	if (ret) {
 		dev_err(dev, "Failed to create NTB EPC\n");
-		goto err_bar_init;
+		return ret;
 	}
 
 	ret = epf_ntb_config_spad_bar_alloc(ntb);

@@ -1569,9 +1556,6 @@ static int epf_ntb_bind(struct pci_epf *epf)
 err_bar_alloc:
 	epf_ntb_config_spad_bar_free(ntb);
 
-err_bar_init:
-	epf_ntb_epc_destroy(ntb);
-
 	return ret;
 }
 

@@ -1587,7 +1571,6 @@ static void epf_ntb_unbind(struct pci_epf *epf)
 
 	epf_ntb_epc_cleanup(ntb);
 	epf_ntb_config_spad_bar_free(ntb);
-	epf_ntb_epc_destroy(ntb);
 
 	pci_unregister_driver(&vntb_pci_driver);
 }

From: Koichiro Den <[email protected]>

[ Upstream commit 0da63230d3ec1ec5fcc443a2314233e95bfece54 ]

epf_ntb_epc_destroy() duplicates the teardown that the caller is supposed to perform later. This leads to an oops when .allow_link fails or when .drop_link is performed. The following is an example oops of the former case:

  Unable to handle kernel paging request at virtual address dead000000000108
  [...]
  [dead000000000108] address between user and kernel address ranges
  Internal error: Oops: 0000000096000044 [#1]  SMP
  [...]
  Call trace:
   pci_epc_remove_epf+0x78/0xe0 (P)
   pci_primary_epc_epf_link+0x88/0xa8
   configfs_symlink+0x1f4/0x5a0
   vfs_symlink+0x134/0x1d8
   do_symlinkat+0x88/0x138
   __arm64_sys_symlinkat+0x74/0xe0
  [...]

Remove the helper, and drop pci_epc_put(). EPC device refcounting is tied to the configfs EPC group lifetime, and pci_epc_put() in the .drop_link path is sufficient.

---
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 18 +-----------------
 1 file changed, 1 insertion(+), 17 deletions(-)

index 45530bca50fb8..e9402b5dc8359 100644
@@ -650,18 +650,6 @@ static void epf_ntb_mw_bar_clear(struct epf_ntb *ntb)
 	}
 }
 
-/**
- * epf_ntb_epc_destroy() - Cleanup NTB EPC interface
- * @ntb: NTB device that facilitates communication between HOST and vHOST
- *
- * Wrapper for epf_ntb_epc_destroy_interface() to cleanup all the NTB interfaces
- */
-static void epf_ntb_epc_destroy(struct epf_ntb *ntb)
-{
-	pci_epc_remove_epf(ntb->epf->epc, ntb->epf, 0);
-	pci_epc_put(ntb->epf->epc);
-}
-
 /**
  * epf_ntb_init_epc_bar() - Identify BARs to be used for each of the NTB
  * constructs (scratchpad region, doorbell, memorywindow)

@@ -1289,7 +1277,7 @@ static int epf_ntb_bind(struct pci_epf *epf)
 	ret = epf_ntb_init_epc_bar(ntb);
 	if (ret) {
 		dev_err(dev, "Failed to create NTB EPC\n");
-		goto err_bar_init;
+		return ret;
 	}
 
 	ret = epf_ntb_config_spad_bar_alloc(ntb);

@@ -1326,9 +1314,6 @@ static int epf_ntb_bind(struct pci_epf *epf)
 err_bar_alloc:
 	epf_ntb_config_spad_bar_free(ntb);
 
-err_bar_init:
-	epf_ntb_epc_destroy(ntb);
-
 	return ret;
 }
 

@@ -1344,7 +1329,6 @@ static void epf_ntb_unbind(struct pci_epf *epf)
 
 	epf_ntb_epc_cleanup(ntb);
 	epf_ntb_config_spad_bar_free(ntb);
-	epf_ntb_epc_destroy(ntb);
 
 	pci_unregister_driver(&vntb_pci_driver);
 }

2.53.0