* [PATCH 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory
@ 2021-01-29 7:39 Anshuman Khandual
2021-01-29 7:39 ` [PATCH 1/2] " Anshuman Khandual
2021-01-29 7:39 ` [PATCH 2/2] arm64/mm: Reorganize pfn_valid() Anshuman Khandual
0 siblings, 2 replies; 4+ messages in thread
From: Anshuman Khandual @ 2021-01-29 7:39 UTC (permalink / raw)
To: linux-arm-kernel, linux-kernel, linux-mm
Cc: Anshuman Khandual, Catalin Marinas, Will Deacon, Ard Biesheuvel,
Mark Rutland, James Morse, Robin Murphy, Jérôme Glisse,
Dan Williams, David Hildenbrand, Mike Rapoport
This series fixes pfn_valid() for ZONE_DEVICE based memory and also improves
its performance for normal hotplug memory. While here, it also reorganizes
pfn_valid() on CONFIG_SPARSEMEM. This series is based on v5.11-rc5.
Question - should pfn_section_valid() be tested both for boot and non boot
memory as well ?
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Changes in V1:
- Test pfn_section_valid() for non boot memory
Changes in RFC:
https://lore.kernel.org/linux-arm-kernel/1608621144-4001-1-git-send-email-anshuman.khandual@arm.com/
Anshuman Khandual (2):
arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory
arm64/mm: Reorganize pfn_valid()
arch/arm64/mm/init.c | 46 +++++++++++++++++++++++++++++++++++++++-----
1 file changed, 41 insertions(+), 5 deletions(-)
--
2.20.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory
2021-01-29 7:39 [PATCH 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Anshuman Khandual
@ 2021-01-29 7:39 ` Anshuman Khandual
2021-01-29 7:39 ` [PATCH 2/2] arm64/mm: Reorganize pfn_valid() Anshuman Khandual
1 sibling, 0 replies; 4+ messages in thread
From: Anshuman Khandual @ 2021-01-29 7:39 UTC (permalink / raw)
To: linux-arm-kernel, linux-kernel, linux-mm
Cc: Anshuman Khandual, Catalin Marinas, Will Deacon, Ard Biesheuvel,
Mark Rutland, James Morse, Robin Murphy, Jérôme Glisse,
Dan Williams, David Hildenbrand, Mike Rapoport
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
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 709d98fea90c..1141075e4d53 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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] arm64/mm: Reorganize pfn_valid()
2021-01-29 7:39 [PATCH 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Anshuman Khandual
2021-01-29 7:39 ` [PATCH 1/2] " Anshuman Khandual
@ 2021-01-29 7:39 ` Anshuman Khandual
[not found] ` <9050792c-feba-1b72-681e-ebc28fc1fcc5@redhat.com>
1 sibling, 1 reply; 4+ messages in thread
From: Anshuman Khandual @ 2021-01-29 7:39 UTC (permalink / raw)
To: linux-arm-kernel, linux-kernel, linux-mm
Cc: Anshuman Khandual, Catalin Marinas, Will Deacon, Ard Biesheuvel,
Mark Rutland, James Morse, Robin Murphy, Jérôme Glisse,
Dan Williams, David Hildenbrand, Mike Rapoport
There are multiple instances of pfn_to_section_nr() and __pfn_to_section()
when CONFIG_SPARSEMEM is enabled. This can be just optimized if the memory
section is fetched earlier. Hence bifurcate pfn_valid() into two different
definitions depending on whether CONFIG_SPARSEMEM is enabled. Also replace
the open coded pfn <--> addr conversion with __[pfn|phys]_to_[phys|pfn]().
This does not cause any functional change.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/arm64/mm/init.c | 38 +++++++++++++++++++++++++++++++-------
1 file changed, 31 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 1141075e4d53..09adca90c57a 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -217,18 +217,25 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
free_area_init(max_zone_pfns);
}
+#ifdef CONFIG_SPARSEMEM
int pfn_valid(unsigned long pfn)
{
- phys_addr_t addr = pfn << PAGE_SHIFT;
+ struct mem_section *ms = __pfn_to_section(pfn);
+ phys_addr_t addr = __pfn_to_phys(pfn);
- if ((addr >> PAGE_SHIFT) != pfn)
+ /*
+ * Ensure the upper PAGE_SHIFT bits are clear in the
+ * pfn. Else it might lead to false positives when
+ * some of the upper bits are set, but the lower bits
+ * match a valid pfn.
+ */
+ if (__phys_to_pfn(addr) != pfn)
return 0;
-#ifdef CONFIG_SPARSEMEM
if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
return 0;
- if (!valid_section(__pfn_to_section(pfn)))
+ if (!valid_section(ms))
return 0;
/*
@@ -240,11 +247,28 @@ int pfn_valid(unsigned long pfn)
* 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
+ if (!early_section(ms))
+ return pfn_section_valid(ms, pfn);
+
return memblock_is_map_memory(addr);
}
+#else
+int pfn_valid(unsigned long pfn)
+{
+ phys_addr_t addr = __pfn_to_phys(pfn);
+
+ /*
+ * Ensure the upper PAGE_SHIFT bits are clear in the
+ * pfn. Else it might lead to false positives when
+ * some of the upper bits are set, but the lower bits
+ * match a valid pfn.
+ */
+ if (__phys_to_pfn(addr) != pfn)
+ return 0;
+
+ return memblock_is_map_memory(addr);
+}
+#endif
EXPORT_SYMBOL(pfn_valid);
static phys_addr_t memory_limit = PHYS_ADDR_MAX;
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] arm64/mm: Reorganize pfn_valid()
[not found] ` <9050792c-feba-1b72-681e-ebc28fc1fcc5@redhat.com>
@ 2021-02-01 3:47 ` Anshuman Khandual
0 siblings, 0 replies; 4+ messages in thread
From: Anshuman Khandual @ 2021-02-01 3:47 UTC (permalink / raw)
To: David Hildenbrand, linux-arm-kernel, linux-kernel, linux-mm
Cc: Catalin Marinas, Will Deacon, Ard Biesheuvel, Mark Rutland,
James Morse, Robin Murphy, Jérôme Glisse, Dan Williams,
Mike Rapoport
On 1/29/21 3:37 PM, David Hildenbrand wrote:
> On 29.01.21 08:39, Anshuman Khandual wrote:
>> There are multiple instances of pfn_to_section_nr() and __pfn_to_section()
>> when CONFIG_SPARSEMEM is enabled. This can be just optimized if the memory
>> section is fetched earlier. Hence bifurcate pfn_valid() into two different
>> definitions depending on whether CONFIG_SPARSEMEM is enabled. Also replace
>> the open coded pfn <--> addr conversion with __[pfn|phys]_to_[phys|pfn]().
>> This does not cause any functional change.
>>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Ard Biesheuvel <ardb@kernel.org>
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> arch/arm64/mm/init.c | 38 +++++++++++++++++++++++++++++++-------
>> 1 file changed, 31 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 1141075e4d53..09adca90c57a 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -217,18 +217,25 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
>> free_area_init(max_zone_pfns);
>> }
>> +#ifdef CONFIG_SPARSEMEM
>> int pfn_valid(unsigned long pfn)
>> {
>> - phys_addr_t addr = pfn << PAGE_SHIFT;
>> + struct mem_section *ms = __pfn_to_section(pfn);
>> + phys_addr_t addr = __pfn_to_phys(pfn);
>
> I'd just use PFN_PHYS() here, which is more frequently used in the kernel.
Sure, will replace.
>
>> - if ((addr >> PAGE_SHIFT) != pfn)
>> + /*
>> + * Ensure the upper PAGE_SHIFT bits are clear in the
>> + * pfn. Else it might lead to false positives when
>> + * some of the upper bits are set, but the lower bits
>> + * match a valid pfn.
>> + */
>> + if (__phys_to_pfn(addr) != pfn)
>
> and here PHYS_PFN(). Comment is helpful. :)
Sure, will replace.
>
>> return 0;
>> -#ifdef CONFIG_SPARSEMEM
>> if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
>> return 0;
>> - if (!valid_section(__pfn_to_section(pfn)))
>> + if (!valid_section(ms))
>> return 0;
>> /*
>> @@ -240,11 +247,28 @@ int pfn_valid(unsigned long pfn)
>> * 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
>> + if (!early_section(ms))
>> + return pfn_section_valid(ms, pfn);
>> +
>> return memblock_is_map_memory(addr);
>> }
>> +#else
>> +int pfn_valid(unsigned long pfn)
>> +{
>> + phys_addr_t addr = __pfn_to_phys(pfn);
>> +
>> + /*
>> + * Ensure the upper PAGE_SHIFT bits are clear in the
>> + * pfn. Else it might lead to false positives when
>> + * some of the upper bits are set, but the lower bits
>> + * match a valid pfn.
>> + */
>> + if (__phys_to_pfn(addr) != pfn)
>> + return 0;
>> +
>> + return memblock_is_map_memory(addr);
>> +}
>
>
> I think you can avoid duplicating the code by doing something like:
Right and also this looks more compact as well. Initially though about
it but then was apprehensive about the style in #ifdef { } #endif code
block inside the function. After this change, the resulting patch also
clears checkpatch.pl test. Will do the change.
>
>
> phys_addr_t addr = PFN_PHYS(pfn);
>
> if (PHYS_PFN(addr) != pfn)
> return 0;
>
> #ifdef CONFIG_SPARSEMEM
> {
> struct mem_section *ms = __pfn_to_section(pfn);
>
> if (!valid_section(ms))
> return 0;
> if (!early_section(ms))
> return pfn_section_valid(ms, pfn);
> }
> #endif
> return memblock_is_map_memory(addr);
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-01-29 7:39 ` [PATCH 2/2] arm64/mm: Reorganize pfn_valid() Anshuman Khandual
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