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Date: Wed, 28 Mar 2018 17:26:40 +0800
From: Jia He <hejianet@...il.com>
To: Daniel Vacek <neelx@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Michal Hocko <mhocko@...e.com>,
Catalin Marinas <catalin.marinas@....com>,
Mel Gorman <mgorman@...e.de>,
Will Deacon <will.deacon@....com>,
Mark Rutland <mark.rutland@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Pavel Tatashin <pasha.tatashin@...cle.com>,
Daniel Jordan <daniel.m.jordan@...cle.com>,
AKASHI Takahiro <takahiro.akashi@...aro.org>,
Gioh Kim <gi-oh.kim@...fitbricks.com>,
Steven Sistare <steven.sistare@...cle.com>,
Eugeniu Rosca <erosca@...adit-jv.com>,
Vlastimil Babka <vbabka@...e.cz>,
open list <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
James Morse <james.morse@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Steve Capper <steve.capper@....com>, x86@...nel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Kate Stewart <kstewart@...uxfoundation.org>,
Philippe Ombredanne <pombredanne@...b.com>,
Johannes Weiner <hannes@...xchg.org>,
Kemi Wang <kemi.wang@...el.com>,
Petr Tesarik <ptesarik@...e.com>,
YASUAKI ISHIMATSU <yasu.isimatu@...il.com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Nikolay Borisov <nborisov@...e.com>,
Jia He <jia.he@...-semitech.com>
Subject: Re: [PATCH v2 1/5] mm: page_alloc: remain memblock_next_valid_pfn()
when CONFIG_HAVE_ARCH_PFN_VALID is enable
On 3/28/2018 12:52 AM, Daniel Vacek Wrote:
> On Sat, Mar 24, 2018 at 1:24 PM, Jia He <hejianet@...il.com> wrote:
>> Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns
>> where possible") optimized the loop in memmap_init_zone(). But it causes
>> possible panic bug. So Daniel Vacek reverted it later.
>>
>> But memblock_next_valid_pfn is valid when CONFIG_HAVE_ARCH_PFN_VALID is
>> enabled. And as verified by Eugeniu Rosca, arm can benifit from this
>> commit. So remain the memblock_next_valid_pfn.
> It is not dependent on CONFIG_HAVE_ARCH_PFN_VALID option but on
> arm(64) implementation of pfn_valid() function, IIUC. So it should
> really be moved from generic source file to arm specific location. I'd
> say somewhere close to the pfn_valid() implementation. Such as to
> arch/arm{,64}/mm/ init.c-ish?
>
> --nX
Hi Daniel
I didn't catch the reason why "It is not dependent on
CONFIG_HAVE_ARCH_PFN_VALID option but
on arm(64) implementation of pfn_valid() function"? Can you explain more
about it? Thanks
What's your thought if I changed the codes as followed?
in include/linux/memblock.h
#ifdef CONFIG_HAVE_ARCH_PFN_VALID
extern unsigned long memblock_next_valid_pfn(unsigned long pfn);
#else
#define memblock_next_valid_pfn(pfn) (pfn + 1)
#endif
Cheers,
Jia
>
>> Signed-off-by: Jia He <jia.he@...-semitech.com>
>> ---
>> include/linux/memblock.h | 4 ++++
>> mm/memblock.c | 29 +++++++++++++++++++++++++++++
>> mm/page_alloc.c | 11 ++++++++++-
>> 3 files changed, 43 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
>> index 0257aee..efbbe4b 100644
>> --- a/include/linux/memblock.h
>> +++ b/include/linux/memblock.h
>> @@ -203,6 +203,10 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
>> i >= 0; __next_mem_pfn_range(&i, nid, p_start, p_end, p_nid))
>> #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
>>
>> +#ifdef CONFIG_HAVE_ARCH_PFN_VALID
>> +unsigned long memblock_next_valid_pfn(unsigned long pfn);
>> +#endif
>> +
>> /**
>> * for_each_free_mem_range - iterate through free memblock areas
>> * @i: u64 used as loop variable
>> diff --git a/mm/memblock.c b/mm/memblock.c
>> index ba7c878..bea5a9c 100644
>> --- a/mm/memblock.c
>> +++ b/mm/memblock.c
>> @@ -1102,6 +1102,35 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
>> *out_nid = r->nid;
>> }
>>
>> +#ifdef CONFIG_HAVE_ARCH_PFN_VALID
>> +unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn)
>> +{
>> + struct memblock_type *type = &memblock.memory;
>> + unsigned int right = type->cnt;
>> + unsigned int mid, left = 0;
>> + phys_addr_t addr = PFN_PHYS(++pfn);
>> +
>> + do {
>> + mid = (right + left) / 2;
>> +
>> + if (addr < type->regions[mid].base)
>> + right = mid;
>> + else if (addr >= (type->regions[mid].base +
>> + type->regions[mid].size))
>> + left = mid + 1;
>> + else {
>> + /* addr is within the region, so pfn is valid */
>> + return pfn;
>> + }
>> + } while (left < right);
>> +
>> + if (right == type->cnt)
>> + return -1UL;
>> + else
>> + return PHYS_PFN(type->regions[right].base);
>> +}
>> +#endif /*CONFIG_HAVE_ARCH_PFN_VALID*/
>> +
>> /**
>> * memblock_set_node - set node ID on memblock regions
>> * @base: base of area to set node ID for
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index c19f5ac..2a967f7 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -5483,8 +5483,17 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
>> if (context != MEMMAP_EARLY)
>> goto not_early;
>>
>> - if (!early_pfn_valid(pfn))
>> + if (!early_pfn_valid(pfn)) {
>> +#if (defined CONFIG_HAVE_MEMBLOCK) && (defined CONFIG_HAVE_ARCH_PFN_VALID)
>> + /*
>> + * Skip to the pfn preceding the next valid one (or
>> + * end_pfn), such that we hit a valid pfn (or end_pfn)
>> + * on our next iteration of the loop.
>> + */
>> + pfn = memblock_next_valid_pfn(pfn) - 1;
>> +#endif
>> continue;
>> + }
>> if (!early_pfn_in_nid(pfn, nid))
>> continue;
>> if (!update_defer_init(pgdat, pfn, end_pfn, &nr_initialised))
>> --
>> 2.7.4
>>
--
Cheers,
Jia
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