Convert struct mem_ctl_info to use flex array and use the new flex
array helpers to simplify initialization.

Add __counted_by for extra runtime analysis when requested.

Move counting assignment immediately after allocation as required by
__counted_by.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
 v2: reword message slightly.
 drivers/edac/edac_mc.c |  9 ++-------
 include/linux/edac.h   | 23 ++++++++++++-----------
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 29e9828422bb..1ffab0269aec 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -203,7 +203,6 @@ static void mci_release(struct device *dev)
 		kfree(mci->csrows);
 	}
 	kfree(mci->pvt_info);
-	kfree(mci->layers);
 	kfree(mci);
 }

@@ -361,25 +360,21 @@ struct mem_ctl_info *edac_mc_alloc(unsigned int mc_num,
 			per_rank = true;
 	}

-	mci = kzalloc_obj(struct mem_ctl_info);
+	mci = kzalloc_flex(*mci, layers, n_layers);
 	if (!mci)
 		return NULL;

-	mci->layers = kzalloc_objs(struct edac_mc_layer, n_layers);
-	if (!mci->layers)
-		goto error;
-
 	mci->pvt_info = kzalloc(sz_pvt, GFP_KERNEL);
 	if (!mci->pvt_info)
 		goto error;

+	mci->n_layers = n_layers;
 	mci->dev.release = mci_release;
 	device_initialize(&mci->dev);

 	/* setup index and various internal pointers */
 	mci->mc_idx = mc_num;
 	mci->tot_dimms = tot_dimms;
-	mci->n_layers = n_layers;
 	memcpy(mci->layers, layers, sizeof(*layer) * n_layers);
 	mci->nr_csrows = tot_csrows;
 	mci->num_cschannel = tot_channels;
diff --git a/include/linux/edac.h b/include/linux/edac.h
index fa32f2aca22f..deba46b3ee25 100644
--- a/include/linux/edac.h
+++ b/include/linux/edac.h
@@ -541,17 +541,6 @@ struct mem_ctl_info {
 	struct csrow_info **csrows;
 	unsigned int nr_csrows, num_cschannel;

-	/*
-	 * Memory Controller hierarchy
-	 *
-	 * There are basically two types of memory controller: the ones that
-	 * sees memory sticks ("dimms"), and the ones that sees memory ranks.
-	 * All old memory controllers enumerate memories per rank, but most
-	 * of the recent drivers enumerate memories per DIMM, instead.
-	 * When the memory controller is per rank, csbased is true.
-	 */
-	unsigned int n_layers;
-	struct edac_mc_layer *layers;
 	bool csbased;

 	/*
@@ -609,6 +598,18 @@ struct mem_ctl_info {
 	u8 fake_inject_layer[EDAC_MAX_LAYERS];
 	bool fake_inject_ue;
 	u16 fake_inject_count;
+
+	/*
+	 * Memory Controller hierarchy
+	 *
+	 * There are basically two types of memory controller: the ones that
+	 * sees memory sticks ("dimms"), and the ones that sees memory ranks.
+	 * All old memory controllers enumerate memories per rank, but most
+	 * of the recent drivers enumerate memories per DIMM, instead.
+	 * When the memory controller is per rank, csbased is true.
+	 */
+	unsigned int n_layers;
+	struct edac_mc_layer layers[] __counted_by(n_layers);
 };

 #define mci_for_each_dimm(mci, dimm)				\
--
2.53.0

> From: Rosen Penev <rosenp@gmail.com>
> Sent: Friday, March 20, 2026 4:15 AM
> To: linux-edac@vger.kernel.org
> Cc: Borislav Petkov <bp@alien8.de>; Luck, Tony <tony.luck@intel.com>; Kees
> Cook <kees@kernel.org>; Gustavo A. R. Silva <gustavoars@kernel.org>; open
> list <linux-kernel@vger.kernel.org>; open list:KERNEL HARDENING (not
> covered by other areas):Keyword:\b__counted_by(_le|_be)?\b <linux-
> hardening@vger.kernel.org>
> Subject: [PATCHv2] EDAC/mc: Use kzalloc_flex()
> 
> Convert struct mem_ctl_info to use flex array and use the new flex array
> helpers to simplify initialization.
> 
> Add __counted_by for extra runtime analysis when requested.
> 
> Move counting assignment immediately after allocation as required by
> __counted_by.
> 
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>

LGTM, 

  Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

Thanks!
-Qiuxu