From: Ard Biesheuvel <ardb@kernel.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
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@linux.ibm.com>, Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH v4 1/4] include/linux/mmzone.h: add documentation for pfn_valid()
Date: Tue, 11 May 2021 12:22:43 +0200 [thread overview]
Message-ID: <CAMj1kXER_hsior1uoy3=7Sca4nD_n1s8PRoN4JMbOjzgL6g+Hg@mail.gmail.com> (raw)
In-Reply-To: <20210511100550.28178-2-rppt@kernel.org>
On Tue, 11 May 2021 at 12:06, Mike Rapoport <rppt@kernel.org> wrote:
>
> 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>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> include/linux/mmzone.h | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 0d53eba1c383..e5945ca24df7 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -1427,6 +1427,17 @@ 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:[~2021-05-11 10:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 10:05 [PATCH v4 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid() Mike Rapoport
2021-05-11 10:05 ` [PATCH v4 1/4] include/linux/mmzone.h: add documentation for pfn_valid() Mike Rapoport
2021-05-11 10:22 ` Ard Biesheuvel [this message]
2021-05-11 10:05 ` [PATCH v4 2/4] memblock: update initialization of reserved pages Mike Rapoport
2021-05-11 10:23 ` Ard Biesheuvel
2021-05-11 10:05 ` [PATCH v4 3/4] arm64: decouple check whether pfn is in linear map from pfn_valid() Mike Rapoport
2021-05-11 10:25 ` Ard Biesheuvel
2021-05-11 10:05 ` [PATCH v4 4/4] arm64: drop pfn_valid_within() and simplify pfn_valid() Mike Rapoport
2021-05-11 10:26 ` Ard Biesheuvel
2021-05-11 23:40 ` Andrew Morton
2021-05-12 5:31 ` Mike Rapoport
2021-05-12 3:13 ` [PATCH v4 0/4] " Kefeng Wang
2021-05-12 7:00 ` Ard Biesheuvel
2021-05-12 7:33 ` Mike Rapoport
2021-05-12 7:59 ` Ard Biesheuvel
2021-05-12 8:32 ` Mike Rapoport
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