On Wed, 2 Aug 2023 15:23:28 +0800 Wupeng Ma <mawupeng1@xxxxxxxxxx> wrote:
> From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
>
> For system with kernelcore=mirror enabled while no mirrored memory is
> reported by efi. This could lead to kernel OOM during startup since
> all memory beside zone DMA are in the movable zone and this prevents
> the kernel to use it.
>
> Zone DMA/DMA32 initialization is independent of mirrored memory and
> their max pfn is set in zone_sizes_init(). Since kernel can fallback
> to zone DMA/DMA32 if there is no memory in zone Normal, these zones
> are seen as mirrored memory no mather their memory attributes are.
>
> To solve this problem, disable kernelcore=mirror when there is no real
> mirrored memory exists.
>
> ...
>
> diff --git a/mm/internal.h b/mm/internal.h
> index a7d9e980429a..b8aaf9cac87e 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1005,6 +1005,7 @@ static inline bool gup_must_unshare(struct vm_area_struct *vma,
> }
>
> extern bool mirrored_kernelcore;
> +extern bool memblock_has_mirror(void);
>
> static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
> {
> diff --git a/mm/memblock.c b/mm/memblock.c
> index f9e61e565a53..913b2520a9a0 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -161,6 +161,11 @@ static int memblock_can_resize __initdata_memblock;
> static int memblock_memory_in_slab __initdata_memblock;
> static int memblock_reserved_in_slab __initdata_memblock;
>
> +bool __init_memblock memblock_has_mirror(void)
> +{
> + return system_has_some_mirror;
> +}
> +
> static enum memblock_flags __init_memblock choose_memblock_flags(void)
> {
> return system_has_some_mirror ? MEMBLOCK_MIRROR : MEMBLOCK_NONE;
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index a1963c3322af..e8af1b628430 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -377,6 +377,11 @@ static void __init find_zone_movable_pfns_for_nodes(void)
> if (mirrored_kernelcore) {
> bool mem_below_4gb_not_mirrored = false;
>
> + if (!memblock_has_mirror()) {
> + pr_warn("The system has no mirror memory, ignore kernelcore=mirror.\n");
> + goto out;
> + }
> +
> for_each_mem_region(r) {
> if (memblock_is_mirror(r))
> continue;
I've already queued Levi's "mm/mm_init: ignore kernelcore=mirror boot
option when no mirror memory presents."
(https://lkml.kernel.org/r/20230802183614.15520-1-ppbuk5246@xxxxxxxxx)
The main difference appears to be that Levi's patch zeroes out
zone_movable_pfn.
Please let's check each other's work and decide how to proceed?
