From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@kernel.org>,
VlastimilBabkavbabka@suse.cz, pasha.tatashin@soleen.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Anshuman Khandual <anshuman.khandual@arm.com>
Subject: Re: [PATCH v2 4/7] mm,memory_hotplug: Enforce struct page size to be multiple of PMD
Date: Mon, 1 Mar 2021 11:24:57 +0100 [thread overview]
Message-ID: <2ba12dc6-bd3b-4d23-4288-13447bb1225d@redhat.com> (raw)
In-Reply-To: <20210301100640.GA32425@linux>
On 01.03.21 11:06, Oscar Salvador wrote:
> On Thu, Feb 25, 2021 at 07:26:50PM +0100, David Hildenbrand wrote:
>> On 09.02.21 14:38, Oscar Salvador wrote:
>>> When struct page's size is not multiple of PMD, these do not get
>>> fully populated when adding sections, hence two sections will
>>> intersect the same the PMD. This goes against the vmemmap-per-device
>>> premise, so reject it if that is the case.
>>>
>>> Signed-off-by: Oscar Salvador <osalvador@suse.de>
>>> ---
>>> mm/memory_hotplug.c | 5 +++--
>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>> index 95695483a622..d3fb036d33fd 100644
>>> --- a/mm/memory_hotplug.c
>>> +++ b/mm/memory_hotplug.c
>>> @@ -57,10 +57,11 @@ static __meminit int memmap_on_memory_store(const char *val,
>>> const struct kernel_param *kp)
>>> {
>>> /*
>>> - * Fail silently in case we cannot enable it due to platform constraints.
>>> + * Fail silently in case we cannot enable it due to system constraints.
>>> * User can always check whether it is enabled or not via /sys/module.
>>> */
>>> - if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE))
>>> + if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) ||
>>> + (PMD_SIZE % sizeof(struct page)))
>>> return 0;
>>> return param_set_bool(val, kp);
>>>
>>
>> Squash that into #1 - it's part of basic operation.
>
> Just to be sure we are on the same page.
> You mean to move this patch and patch#5 into the runtime check in
> mhp_supports_memmap_on_memory(), right?
Yes, then the compiler might even be able to figure out that what
follows the check is dead code.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-03-01 10:25 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 13:38 [PATCH v2 0/7] Allocate memmap from hotadded memory (per device) Oscar Salvador
2021-02-09 13:38 ` [PATCH v2 1/7] mm,memory_hotplug: Allocate memmap from the added memory range Oscar Salvador
2021-02-25 18:58 ` David Hildenbrand
2021-02-28 18:50 ` Oscar Salvador
2021-03-01 8:30 ` David Hildenbrand
2021-03-01 8:32 ` David Hildenbrand
2021-02-09 13:38 ` [PATCH v2 2/7] acpi,memhotplug: Enable MHP_MEMMAP_ON_MEMORY when supported Oscar Salvador
2021-02-09 13:38 ` [PATCH v2 3/7] mm,memory_hotplug: Add kernel boot option to enable memmap_on_memory Oscar Salvador
2021-02-25 18:25 ` David Hildenbrand
2021-02-26 12:14 ` Oscar Salvador
2021-03-01 8:27 ` David Hildenbrand
2021-02-09 13:38 ` [PATCH v2 4/7] mm,memory_hotplug: Enforce struct page size to be multiple of PMD Oscar Salvador
2021-02-25 18:26 ` David Hildenbrand
2021-02-26 12:06 ` Oscar Salvador
2021-03-01 10:06 ` Oscar Salvador
2021-03-01 10:24 ` David Hildenbrand [this message]
2021-02-09 13:38 ` [PATCH v2 5/7] mm,memory_hotplug: Enforce pageblock alignment when memmap_on_memory Oscar Salvador
2021-02-25 18:27 ` David Hildenbrand
2021-02-26 12:06 ` Oscar Salvador
2021-02-09 13:38 ` [PATCH v2 6/7] x86/Kconfig: Introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE Oscar Salvador
2021-02-25 18:29 ` David Hildenbrand
2021-02-26 12:04 ` Oscar Salvador
2021-03-01 8:45 ` David Hildenbrand
2021-03-01 10:07 ` Oscar Salvador
2021-02-09 13:38 ` [PATCH v2 7/7] arm64/Kconfig: " Oscar Salvador
2021-02-25 18:29 ` David Hildenbrand
2021-02-26 12:10 ` Oscar Salvador
2021-02-17 10:18 ` [PATCH v2 0/7] Allocate memmap from hotadded memory (per device) Oscar Salvador
2021-02-22 11:15 ` Oscar Salvador
2021-02-22 11:28 ` David Hildenbrand
2021-02-23 7:48 ` Oscar Salvador
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