[v5.4 stable] arm: stm32: Regression observed on "no-map" reserved memory region

From: Alexandre TORGUE <alexandre.torgue@foss.st.com>
To: Quentin Perret <qperret@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sasha Levin <sashal@kernel.org>
Cc: <stable@vger.kernel.org>, Rob Herring <robh+dt@kernel.org>
Subject: [v5.4 stable] arm: stm32: Regression observed on "no-map" reserved memory region
Date: Tue, 20 Apr 2021 16:02:58 +0200	[thread overview]
Message-ID: <4a4734d6-49df-677b-71d3-b926c44d89a9@foss.st.com> (raw)

Hi,

Since v5.4.102 I observe a regression on stm32mp1 platform: "no-map" 
reserved-memory regions are no more "reserved" and make part of the 
kernel System RAM. This causes allocation failure for devices which try 
to take a reserved-memory region.

It has been introduced by the following path:

"fdt: Properly handle "no-map" field in the memory region
[ Upstream commit 86588296acbfb1591e92ba60221e95677ecadb43 ]"
which replace memblock_remove by memblock_mark_nomap in no-map case.

Reverting this patch it's fine.

I add part of my DT (something is maybe wrong inside):

memory@c0000000 {
	reg = <0xc0000000 0x20000000>;
};

reserved-memory {
	#address-cells = <1>;
	#size-cells = <1>;
	ranges;

	gpu_reserved: gpu@d4000000 {
		reg = <0xd4000000 0x4000000>;
		no-map;
	};
};

Sorry if this issue has already been raised and discussed.

Thanks
alex