From: Anshuman Khandual <anshuman.khandual@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: "Anshuman Khandual" <anshuman.khandual@arm.com>, "Catalin Marinas" <catalin.marinas@arm.com>, "Will Deacon" <will@kernel.org>, "Ard Biesheuvel" <ardb@kernel.org>, "Mark Rutland" <mark.rutland@arm.com>, "James Morse" <james.morse@arm.com>, "Robin Murphy" <robin.murphy@arm.com>, "Jérôme Glisse" <jglisse@redhat.com>, "Dan Williams" <dan.j.williams@intel.com>, "David Hildenbrand" <david@redhat.com>, "Mike Rapoport" <rppt@linux.ibm.com>, "Veronika Kabatova" <vkabatov@redhat.com> Subject: [PATCH V3 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Date: Fri, 5 Mar 2021 10:54:57 +0530 [thread overview] Message-ID: <1614921898-4099-2-git-send-email-anshuman.khandual@arm.com> (raw) In-Reply-To: <1614921898-4099-1-git-send-email-anshuman.khandual@arm.com> pfn_valid() validates a pfn but basically it checks for a valid struct page backing for that pfn. It should always return positive for memory ranges backed with struct page mapping. But currently pfn_valid() fails for all ZONE_DEVICE based memory types even though they have struct page mapping. pfn_valid() asserts that there is a memblock entry for a given pfn without MEMBLOCK_NOMAP flag being set. The problem with ZONE_DEVICE based memory is that they do not have memblock entries. Hence memblock_is_map_memory() will invariably fail via memblock_search() for a ZONE_DEVICE based address. This eventually fails pfn_valid() which is wrong. memblock_is_map_memory() needs to be skipped for such memory ranges. As ZONE_DEVICE memory gets hotplugged into the system via memremap_pages() called from a driver, their respective memory sections will not have SECTION_IS_EARLY set. Normal hotplug memory will never have MEMBLOCK_NOMAP set in their memblock regions. Because the flag MEMBLOCK_NOMAP was specifically designed and set for firmware reserved memory regions. memblock_is_map_memory() can just be skipped as its always going to be positive and that will be an optimization for the normal hotplug memory. Like ZONE_DEVICE based memory, all normal hotplugged memory too will not have SECTION_IS_EARLY set for their sections Skipping memblock_is_map_memory() for all non early memory sections would fix pfn_valid() problem for ZONE_DEVICE based memory and also improve its performance for normal hotplug memory as well. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Robin Murphy <robin.murphy@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Acked-by: David Hildenbrand <david@redhat.com> Fixes: 73b20c84d42d ("arm64: mm: implement pte_devmap support") Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- arch/arm64/mm/init.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 0ace5e68efba..5920c527845a 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -230,6 +230,18 @@ int pfn_valid(unsigned long pfn) if (!valid_section(__pfn_to_section(pfn))) return 0; + + /* + * ZONE_DEVICE memory does not have the memblock entries. + * memblock_is_map_memory() check for ZONE_DEVICE based + * addresses will always fail. Even the normal hotplugged + * memory will never have MEMBLOCK_NOMAP flag set in their + * memblock entries. Skip memblock search for all non early + * memory sections covering all of hotplug memory including + * both normal and ZONE_DEVICE based. + */ + if (!early_section(__pfn_to_section(pfn))) + return pfn_section_valid(__pfn_to_section(pfn), pfn); #endif return memblock_is_map_memory(addr); } -- 2.20.1
WARNING: multiple messages have this Message-ID (diff)
From: Anshuman Khandual <anshuman.khandual@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: "Anshuman Khandual" <anshuman.khandual@arm.com>, "Catalin Marinas" <catalin.marinas@arm.com>, "Will Deacon" <will@kernel.org>, "Ard Biesheuvel" <ardb@kernel.org>, "Mark Rutland" <mark.rutland@arm.com>, "James Morse" <james.morse@arm.com>, "Robin Murphy" <robin.murphy@arm.com>, "Jérôme Glisse" <jglisse@redhat.com>, "Dan Williams" <dan.j.williams@intel.com>, "David Hildenbrand" <david@redhat.com>, "Mike Rapoport" <rppt@linux.ibm.com>, "Veronika Kabatova" <vkabatov@redhat.com> Subject: [PATCH V3 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Date: Fri, 5 Mar 2021 10:54:57 +0530 [thread overview] Message-ID: <1614921898-4099-2-git-send-email-anshuman.khandual@arm.com> (raw) In-Reply-To: <1614921898-4099-1-git-send-email-anshuman.khandual@arm.com> pfn_valid() validates a pfn but basically it checks for a valid struct page backing for that pfn. It should always return positive for memory ranges backed with struct page mapping. But currently pfn_valid() fails for all ZONE_DEVICE based memory types even though they have struct page mapping. pfn_valid() asserts that there is a memblock entry for a given pfn without MEMBLOCK_NOMAP flag being set. The problem with ZONE_DEVICE based memory is that they do not have memblock entries. Hence memblock_is_map_memory() will invariably fail via memblock_search() for a ZONE_DEVICE based address. This eventually fails pfn_valid() which is wrong. memblock_is_map_memory() needs to be skipped for such memory ranges. As ZONE_DEVICE memory gets hotplugged into the system via memremap_pages() called from a driver, their respective memory sections will not have SECTION_IS_EARLY set. Normal hotplug memory will never have MEMBLOCK_NOMAP set in their memblock regions. Because the flag MEMBLOCK_NOMAP was specifically designed and set for firmware reserved memory regions. memblock_is_map_memory() can just be skipped as its always going to be positive and that will be an optimization for the normal hotplug memory. Like ZONE_DEVICE based memory, all normal hotplugged memory too will not have SECTION_IS_EARLY set for their sections Skipping memblock_is_map_memory() for all non early memory sections would fix pfn_valid() problem for ZONE_DEVICE based memory and also improve its performance for normal hotplug memory as well. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Robin Murphy <robin.murphy@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Acked-by: David Hildenbrand <david@redhat.com> Fixes: 73b20c84d42d ("arm64: mm: implement pte_devmap support") Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- arch/arm64/mm/init.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 0ace5e68efba..5920c527845a 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -230,6 +230,18 @@ int pfn_valid(unsigned long pfn) if (!valid_section(__pfn_to_section(pfn))) return 0; + + /* + * ZONE_DEVICE memory does not have the memblock entries. + * memblock_is_map_memory() check for ZONE_DEVICE based + * addresses will always fail. Even the normal hotplugged + * memory will never have MEMBLOCK_NOMAP flag set in their + * memblock entries. Skip memblock search for all non early + * memory sections covering all of hotplug memory including + * both normal and ZONE_DEVICE based. + */ + if (!early_section(__pfn_to_section(pfn))) + return pfn_section_valid(__pfn_to_section(pfn), pfn); #endif return memblock_is_map_memory(addr); } -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-05 5:24 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-05 5:24 [PATCH V3 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Anshuman Khandual 2021-03-05 5:24 ` Anshuman Khandual 2021-03-05 5:24 ` Anshuman Khandual [this message] 2021-03-05 5:24 ` [PATCH V3 1/2] " Anshuman Khandual 2021-03-05 18:13 ` Catalin Marinas 2021-03-05 18:13 ` Catalin Marinas 2021-03-05 18:24 ` David Hildenbrand 2021-03-05 18:24 ` David Hildenbrand 2021-03-08 11:29 ` Catalin Marinas 2021-03-08 11:29 ` Catalin Marinas 2021-03-08 17:59 ` Catalin Marinas 2021-03-08 17:59 ` Catalin Marinas 2021-03-05 5:24 ` [PATCH V3 2/2] arm64/mm: Reorganize pfn_valid() Anshuman Khandual 2021-03-05 5:24 ` Anshuman Khandual 2021-03-08 18:00 ` Catalin Marinas 2021-03-08 18:00 ` Catalin Marinas 2021-03-05 5:38 ` [PATCH V3 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Anshuman Khandual 2021-03-05 5:38 ` Anshuman Khandual 2021-03-05 12:28 ` Veronika Kabatova 2021-03-05 12:28 ` Veronika Kabatova 2021-03-05 18:16 ` Veronika Kabatova 2021-03-05 18:16 ` Veronika Kabatova 2021-03-05 18:22 ` Catalin Marinas 2021-03-05 18:22 ` Catalin Marinas 2021-03-08 19:16 ` Will Deacon 2021-03-08 19:16 ` Will Deacon
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