Re: [PATCH v3 0/5] of: reserved_mem: several fixes about reserved memory

[Mike Rapoport <rppt@kernel.org>]

On Sun, Sep 20, 2026 at 05:28:47PM +0800, Wandun Chen wrote:
> From: Wandun Chen <chenwandun@lixiang.com>
> 
> This series fixes several error-handling issues in the reserved-memory
> initialization paths.
> 
> The first two patches fix cleanup of no-map regions after driver
> initialization failure.
> 
> Static reserved-memory nodes are reserved during the early DT scan but
> initialized later. The third patch tags regions whose early reservation
> succeeded, so the late scan can skip the nodes whose early reservation
> failed.
> 
> The last two patches reject overlapping static regions. Without
> these checks, overlapping nodes can be initialized over the same
> physical memory, result in data corrupt.
> 
> Sashiko reported these issues in [1] [2] [3].
> 
> [1] https://sashiko.dev/#/message/20260814090305.4C8741F00A3D%40smtp.kernel.org
> [2] https://sashiko.dev/#/message/20260814084718.29C341F000E9%40smtp.kernel.org
> [3] https://sashiko.dev/#/message/20260806100605.2C2C01F000E9%40smtp.kernel.org
> 
> v2 --> v3:
> 1. Rework the mechanism that checks in the late scan whether the early
>    reservation succeeded (patches 3-5, suggested by Marek, thanks).
> 
>    Patch 3 adds a new memblock flag MEMBLOCK_RSRV_RMEM, which is set when
>    the early reservation of a static region succeeds and checked in the
>    late scan.

Can we keep this local to of_reserved_mem please?
 
>    Patches 4 and 5 are reworked to reject regions that overlap or are
>    contained by an existing reservation. The code makes a little different
>    from what was acked in v2, so the Acked-by tags for these patches are not
>    carried over.
> 
> 2. Reorder the patches: the two cleanup fixes in v2 now come first.
>    In v3, the first patch now introduces the 'dynamic' distinction in
>    fdt_init_reserved_mem_node(), which the following patche 3 build on,
>    so the series reads more fluently.
> 
> v1 --> v2:
> 1. Rework failed-node tracking in patch 1: do not track zero-sized nodes,
>    and keep a reserved_mem slot when tracking overflows.
> 2. Reject static reserved regions overlapping existing no-map regions.
> 3. Keep MEMBLOCK_NOMAP flag for static no-map regions when init failure.
> 
> 
> Wandun Chen (5):
>   of: reserved_mem: release dynamically allocated no-map region on init
>     failure
>   of: reserved_mem: retain static no-map memory on init failure
>   of: reserved_mem: skip init for regions whose early reservation failed
>   of: reserved_mem: reject static regions overlapping no-map memory
>   of: reserved_mem: reject static mapped regions overlapping existing
>     reservations
> 
>  drivers/of/of_reserved_mem.c | 86 +++++++++++++++++++++++++-------
>  include/linux/memblock.h     |  7 +++
>  mm/memblock.c                | 95 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 170 insertions(+), 18 deletions(-)
> 
> -- 
> 2.43.0
> 

-- 
Sincerely yours,
Mike.