FAILED: patch "[PATCH] nvme: fix PCIe subsystem reset controller state transition" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

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 <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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 0edb475ac0a7d153318a24d4dca175a270a5cc4f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026012013-strive-tying-5ac1@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 0edb475ac0a7d153318a24d4dca175a270a5cc4f Mon Sep 17 00:00:00 2001
From: Nilay Shroff <nilay@linux.ibm.com>
Date: Wed, 14 Jan 2026 12:54:13 +0530
Subject: [PATCH] nvme: fix PCIe subsystem reset controller state transition
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The commit d2fe192348f9 (“nvme: only allow entering LIVE from CONNECTING
state”) disallows controller state transitions directly from RESETTING
to LIVE. However, the NVMe PCIe subsystem reset path relies on this
transition to recover the controller on PowerPC (PPC) systems.

On PPC systems, issuing a subsystem reset causes a temporary loss of
communication with the NVMe adapter. A subsequent PCIe MMIO read then
triggers EEH recovery, which restores the PCIe link and brings the
controller back online. For EEH recovery to proceed correctly, the
controller must transition back to the LIVE state.

Due to the changes introduced by commit d2fe192348f9 (“nvme: only allow
entering LIVE from CONNECTING state”), the controller can no longer
transition directly from RESETTING to LIVE. As a result, EEH recovery
exits prematurely, leaving the controller stuck in the RESETTING state.

Fix this by explicitly transitioning the controller state from RESETTING
to CONNECTING and then to LIVE. This satisfies the updated state
transition rules and allows the controller to be successfully recovered
on PPC systems following a PCIe subsystem reset.

Cc: stable@vger.kernel.org
Fixes: d2fe192348f9 ("nvme: only allow entering LIVE from CONNECTING state")
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 29e715d5b8f3..58f3097888a7 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1532,7 +1532,10 @@ static int nvme_pci_subsystem_reset(struct nvme_ctrl *ctrl)
 	}
 
 	writel(NVME_SUBSYS_RESET, dev->bar + NVME_REG_NSSR);
-	nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE);
+
+	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_CONNECTING) ||
+	    !nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE))
+		goto unlock;
 
 	/*
 	 * Read controller status to flush the previous write and trigger a