From: Mike Rapoport <rppt@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
David Hildenbrand <david@redhat.com>,
Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mike Rapoport <rppt@kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>, Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH v3 1/4] include/linux/mmzone.h: add documentation for pfn_valid()
Date: Thu, 22 Apr 2021 09:18:59 +0300 [thread overview]
Message-ID: <20210422061902.21614-2-rppt@kernel.org> (raw)
In-Reply-To: <20210422061902.21614-1-rppt@kernel.org>
From: Mike Rapoport <rppt@linux.ibm.com>
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().
Suggested-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
include/linux/mmzone.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 47946cec7584..961f0eeefb62 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1410,6 +1410,17 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
#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;
--
2.28.0
next prev parent reply other threads:[~2021-04-22 6:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 6:18 [PATCH v3 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid() Mike Rapoport
2021-04-22 6:18 ` Mike Rapoport [this message]
2021-04-22 6:19 ` [PATCH v3 2/4] memblock: update initialization of reserved pages Mike Rapoport
2021-04-22 6:19 ` [PATCH v3 3/4] arm64: decouple check whether pfn is in linear map from pfn_valid() Mike Rapoport
2021-04-22 8:57 ` David Hildenbrand
2021-04-22 6:19 ` [PATCH v3 4/4] arm64: drop pfn_valid_within() and simplify pfn_valid() Mike Rapoport
2021-04-22 7:50 ` [RFC V2] mm: Enable generic pfn_valid() to handle early sections with memmap holes Anshuman Khandual
2021-04-22 8:27 ` Mike Rapoport
2021-04-22 11:23 ` Anshuman Khandual
2021-04-22 12:19 ` Mike Rapoport
2021-04-22 9:03 ` David Hildenbrand
2021-04-22 9:42 ` Mike Rapoport
2021-04-22 9:48 ` David Hildenbrand
2021-04-22 10:03 ` Mike Rapoport
2021-04-22 9:59 ` Anshuman Khandual
2021-05-24 4:58 ` Anshuman Khandual
2021-05-24 6:52 ` Mike Rapoport
2021-05-25 6:00 ` Anshuman Khandual
2021-05-25 6:32 ` Mike Rapoport
2021-05-25 9:52 ` Anshuman Khandual
2021-05-25 10:03 ` Mike Rapoport
2021-05-25 10:04 ` David Hildenbrand
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