The patch titled
Subject: include/linux/mmzone.h: add documentation for pfn_valid()
has been added to the -mm tree. Its filename is
include-linux-mmzoneh-add-documentation-for-pfn_valid.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/include-linux-mmzoneh-add-documentation-for-pfn_valid.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/include-linux-mmzoneh-add-documentation-for-pfn_valid.patch
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------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Subject: include/linux/mmzone.h: add documentation for pfn_valid()
Patch series "arm64: drop pfn_valid_within() and simplify pfn_valid()", v4.
These patches aim to remove CONFIG_HOLES_IN_ZONE and essentially hardwire
pfn_valid_within() to 1.
The idea is to mark NOMAP pages as reserved in the memory map and restore
the intended semantics of pfn_valid() to designate availability of struct
page for a pfn.
With this the core mm will be able to cope with the fact that it cannot
use NOMAP pages and the holes created by NOMAP ranges within MAX_ORDER
blocks will be treated correctly even without the need for
pfn_valid_within.
This patch (of 4):
Add comment describing the semantics of pfn_valid() that clarifies that
pfn_valid() only checks for availability of a memory map entry (i.e.
struct page) for a PFN rather than availability of usable memory backing
that PFN.
The most "generic" version of pfn_valid() used by the configurations with
SPARSEMEM enabled resides in include/linux/mmzone.h so this is the most
suitable place for documentation about semantics of pfn_valid().
Link: https://lkml.kernel.org/r/20210511100550.28178-1-rppt@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210511100550.28178-2-rppt@xxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Suggested-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/include/linux/mmzone.h~include-linux-mmzoneh-add-documentation-for-pfn_valid
+++ a/include/linux/mmzone.h
@@ -1416,6 +1416,17 @@ static inline int pfn_section_valid(stru
#endif
#ifndef CONFIG_HAVE_ARCH_PFN_VALID
+/**
+ * pfn_valid - check if there is a valid memory map entry for a PFN
+ * @pfn: the page frame number to check
+ *
+ * Check if there is a valid memory map entry aka struct page for the @pfn.
+ * Note, that availability of the memory map entry does not imply that
+ * there is actual usable memory at that @pfn. The struct page may
+ * represent a hole or an unusable page frame.
+ *
+ * Return: 1 for PFNs that have memory map entries and 0 otherwise
+ */
static inline int pfn_valid(unsigned long pfn)
{
struct mem_section *ms;
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxx are
mm-mmzoneh-simplify-is_highmem_idx.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-set_direct_map__noflush-for-multiple-pages.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
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3.patch
pm-hibernate-disable-when-there-are-active-secretmem-users.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant-fix.patch
secretmem-test-add-basic-selftest-for-memfd_secret2.patch
secretmem-test-add-basic-selftest-for-memfd_secret2-fix.patch
