From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f69.google.com (mail-it0-f69.google.com [209.85.214.69]) by kanga.kvack.org (Postfix) with ESMTP id 263B86B002E for ; Wed, 28 Mar 2018 05:27:02 -0400 (EDT) Received: by mail-it0-f69.google.com with SMTP id 12-v6so1856678itv.9 for ; Wed, 28 Mar 2018 02:27:02 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id g201-v6sor1684268ita.101.2018.03.28.02.27.00 for (Google Transport Security); Wed, 28 Mar 2018 02:27:00 -0700 (PDT) Subject: Re: [PATCH v2 1/5] mm: page_alloc: remain memblock_next_valid_pfn() when CONFIG_HAVE_ARCH_PFN_VALID is enable References: <1521894282-6454-1-git-send-email-hejianet@gmail.com> <1521894282-6454-2-git-send-email-hejianet@gmail.com> From: Jia He Message-ID: <113cb8cf-7c59-4fbb-5ad2-4ae6eeb1193c@gmail.com> Date: Wed, 28 Mar 2018 17:26:40 +0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Daniel Vacek Cc: Andrew Morton , Michal Hocko , Catalin Marinas , Mel Gorman , Will Deacon , Mark Rutland , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Pavel Tatashin , Daniel Jordan , AKASHI Takahiro , Gioh Kim , Steven Sistare , Eugeniu Rosca , Vlastimil Babka , open list , linux-mm@kvack.org, James Morse , Ard Biesheuvel , Steve Capper , x86@kernel.org, Greg Kroah-Hartman , Kate Stewart , Philippe Ombredanne , Johannes Weiner , Kemi Wang , Petr Tesarik , YASUAKI ISHIMATSU , Andrey Ryabinin , Nikolay Borisov , Jia He On 3/28/2018 12:52 AM, Daniel Vacek Wrote: > On Sat, Mar 24, 2018 at 1:24 PM, Jia He 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 >> --- >> 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