The patch titled
Subject: arc: update comment about HIGHMEM implementation
has been added to the -mm tree. Its filename is
arc-update-comment-about-highmem-implementation.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/arc-update-comment-about-highmem-implementation.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/arc-update-comment-about-highmem-implementation.patch
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------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Subject: arc: update comment about HIGHMEM implementation
Arc does not use DISCONTIGMEM to implement high memory, update the comment
describing how high memory works to reflect this.
Link: https://lkml.kernel.org/r/20210608091316.3622-3-rppt@xxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Acked-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arc/mm/init.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
--- a/arch/arc/mm/init.c~arc-update-comment-about-highmem-implementation
+++ a/arch/arc/mm/init.c
@@ -139,16 +139,13 @@ void __init setup_arch_memory(void)
#ifdef CONFIG_HIGHMEM
/*
- * Populate a new node with highmem
- *
* On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
- * than addresses in normal ala low memory (0x8000_0000 based).
+ * than addresses in normal aka low memory (0x8000_0000 based).
* Even with PAE, the huge peripheral space hole would waste a lot of
- * mem with single mem_map[]. This warrants a mem_map per region design.
- * Thus HIGHMEM on ARC is imlemented with DISCONTIGMEM.
- *
- * DISCONTIGMEM in turns requires multiple nodes. node 0 above is
- * populated with normal memory zone while node 1 only has highmem
+ * mem with single contiguous mem_map[].
+ * Thus when HIGHMEM on ARC is enabled the memory map corresponding
+ * to the hole is freed and ARC specific version of pfn_valid()
+ * handles the hole in the memory map.
*/
#ifdef CONFIG_DISCONTIGMEM
node_set_online(1);
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxx are
mm-mmzoneh-simplify-is_highmem_idx.patch
alpha-remove-discontigmem-and-numa.patch
arc-update-comment-about-highmem-implementation.patch
arc-remove-support-for-discontigmem.patch
m68k-remove-support-for-discontigmem.patch
mm-remove-config_discontigmem.patch
arch-mm-remove-stale-mentions-of-disconigmem.patch
docs-remove-description-of-discontigmem.patch
mm-replace-config_need_multiple_nodes-with-config_numa.patch
mm-replace-config_flat_node_mem_map-with-config_flatmem.patch
docs-procrst-meminfo-briefly-describe-gaps-in-memory-accounting.patch
include-linux-mmzoneh-add-documentation-for-pfn_valid.patch
memblock-update-initialization-of-reserved-pages.patch
arm64-decouple-check-whether-pfn-is-in-linear-map-from-pfn_valid.patch
arm64-drop-pfn_valid_within-and-simplify-pfn_valid.patch
mmap-make-mlock_future_check-global.patch
riscv-kconfig-make-direct-map-manipulation-options-depend-on-mmu.patch
set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas.patch
pm-hibernate-disable-when-there-are-active-secretmem-users.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant.patch
secretmem-test-add-basic-selftest-for-memfd_secret2.patch
