From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: Qian Cai <cai@lca.pw>, Dan Williams <dan.j.williams@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -next] mm/hotplug: skip bad PFNs from pfn_to_online_page()
Date: Fri, 14 Jun 2019 21:48:13 +0530 [thread overview]
Message-ID: <c3f2c05d-e42f-c942-1385-664f646ddd33@linux.ibm.com> (raw)
In-Reply-To: <20190614153535.GA9900@linux>
On 6/14/19 9:05 PM, Oscar Salvador wrote:
> On Fri, Jun 14, 2019 at 02:28:40PM +0530, Aneesh Kumar K.V wrote:
>> Can you check with this change on ppc64. I haven't reviewed this series yet.
>> I did limited testing with change . Before merging this I need to go
>> through the full series again. The vmemmap poplulate on ppc64 needs to
>> handle two translation mode (hash and radix). With respect to vmemap
>> hash doesn't setup a translation in the linux page table. Hence we need
>> to make sure we don't try to setup a mapping for a range which is
>> arleady convered by an existing mapping.
>>
>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
>> index a4e17a979e45..15c342f0a543 100644
>> --- a/arch/powerpc/mm/init_64.c
>> +++ b/arch/powerpc/mm/init_64.c
>> @@ -88,16 +88,23 @@ static unsigned long __meminit vmemmap_section_start(unsigned long page)
>> * which overlaps this vmemmap page is initialised then this page is
>> * initialised already.
>> */
>> -static int __meminit vmemmap_populated(unsigned long start, int page_size)
>> +static bool __meminit vmemmap_populated(unsigned long start, int page_size)
>> {
>> unsigned long end = start + page_size;
>> start = (unsigned long)(pfn_to_page(vmemmap_section_start(start)));
>>
>> - for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
>> - if (pfn_valid(page_to_pfn((struct page *)start)))
>> - return 1;
>> + for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page))) {
>>
>> - return 0;
>> + struct mem_section *ms;
>> + unsigned long pfn = page_to_pfn((struct page *)start);
>> +
>> + if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
>> + return 0;
>
> I might be missing something, but is this right?
> Having a section_nr above NR_MEM_SECTIONS is invalid, but if we return 0 here,
> vmemmap_populate will go on and populate it.
I should drop that completely. We should not hit that condition at all.
I will send a final patch once I go through the full patch series making
sure we are not breaking any ppc64 details.
Wondering why we did the below
#if defined(ARCH_SUBSECTION_SHIFT)
#define SUBSECTION_SHIFT (ARCH_SUBSECTION_SHIFT)
#elif defined(PMD_SHIFT)
#define SUBSECTION_SHIFT (PMD_SHIFT)
#else
/*
* Memory hotplug enabled platforms avoid this default because they
* either define ARCH_SUBSECTION_SHIFT, or PMD_SHIFT is a constant, but
* this is kept as a backstop to allow compilation on
* !ARCH_ENABLE_MEMORY_HOTPLUG archs.
*/
#define SUBSECTION_SHIFT 21
#endif
why not
#if defined(ARCH_SUBSECTION_SHIFT)
#define SUBSECTION_SHIFT (ARCH_SUBSECTION_SHIFT)
#else
#define SUBSECTION_SHIFT SECTION_SHIFT
#endif
ie, if SUBSECTION is not supported by arch we have one sub-section per
section?
-aneesh
next prev parent reply other threads:[~2019-06-14 16:18 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 19:15 [PATCH -next] mm/hotplug: skip bad PFNs from pfn_to_online_page() Qian Cai
2019-06-12 19:37 ` Dan Williams
2019-06-12 19:38 ` Dan Williams
2019-06-12 21:47 ` Qian Cai
2019-06-12 21:52 ` Dan Williams
2019-06-12 23:13 ` Dan Williams
2019-06-13 0:06 ` Dan Williams
2019-06-14 8:58 ` Aneesh Kumar K.V
2019-06-14 14:59 ` Qian Cai
2019-06-14 18:03 ` Dan Williams
2019-06-14 18:57 ` Dan Williams
2019-06-14 19:40 ` Qian Cai
2019-06-14 19:48 ` Dan Williams
2019-06-14 20:43 ` Qian Cai
2019-06-16 15:42 ` Dan Williams
2019-06-17 2:25 ` Qian Cai
2019-06-14 15:35 ` Oscar Salvador
2019-06-14 16:18 ` Aneesh Kumar K.V [this message]
2019-06-14 16:22 ` Dan Williams
2019-06-14 16:26 ` Aneesh Kumar K.V
2019-06-14 16:36 ` Dan Williams
2019-06-14 16:50 ` Aneesh Kumar K.V
2019-06-14 16:55 ` Aneesh Kumar K.V
2019-06-14 17:08 ` Jeff Moyer
2019-06-14 17:14 ` Dan Williams
2019-06-14 17:40 ` Aneesh Kumar K.V
2019-06-16 3:49 ` Aneesh Kumar K.V
2019-06-17 17:21 ` Dan Williams
2019-06-13 18:42 ` Qian Cai
2019-06-14 1:17 ` Dan Williams
2019-06-14 1:29 ` Qian Cai
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