Re: [PATCH v3] arm64: dts: qcom: sm6125: enlarge reserved_mem1

[Konrad Dybcio]

On 10/26/26 6:44 PM, Roman Linev wrote:
> reserved_mem1@46200000 is sized 0x2d00000 (45 MiB) in the SoC dtsi, so it
> ends at 0x48f00000, while camera_mem begins at 0x4ab00000. The reference
> firmware memory map for sm6125 reserves 0x4900000 (73 MiB) at this base,
> ending exactly where camera_mem starts, so the 28 MiB in between belongs to
> firmware and not to the kernel. The dtsi nevertheless leaves that span as
> normal System RAM and hands it to the page allocator.
> 
> Every sm6125 board inherits this reservation and none of them overrides it
> or places another region in the gap, so size it for the firmware map in the
> common dtsi.
> 
> On laurel-sprout the mismatch is observable: page-cache pressure eventually
> reaches the span, and a store into it never completes, which hard-locks the
> machine. Before this change the board wedged at roughly one lockup per
> 59 MiB of buffered reads; after enlarging the region the same workload ran
> 691 GiB of buffered reads with no lockups. Booting with CONFIG_MEMTEST=y
> and memtest=1 sweeps 17 free ranges with no bad ranges reported and skips
> 0x46200000..0x4ab00000 entirely, confirming the carveout is out of the page
> allocator's pool.
> 
> The downstream laurel_sprout device tree describes the same base as
> removed_region@46200000 with a size of 0x4900000, so the reserved bytes are
> not a new claim about this hardware family.
> 
> Signed-off-by: Roman Linev <admin@xxxxxxxx>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>

Konrad