linux-kernel - Re: [PATCH 1/2] Revert "x86/e820: put !E820_TYPE

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Date:   Mon, 27 Aug 2018 13:29:57 +0000
From:   Pasha Tatashin <Pavel.Tatashin@...rosoft.com>
To:     "msys.mizuma@...il.com" <msys.mizuma@...il.com>
CC:     "mhocko@...nel.org" <mhocko@...nel.org>,
        "n-horiguchi@...jp.nec.com" <n-horiguchi@...jp.nec.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Masayoshi Mizuma <m.mizuma@...fujitsu.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "osalvador@...hadventures.net" <osalvador@...hadventures.net>
Subject: Re: [PATCH 1/2] Revert "x86/e820: put !E820_TYPE_RAM regions into
 memblock.reserved"

On Mon, Aug 27, 2018 at 8:31 AM Masayoshi Mizuma <msys.mizuma@...il.com> wrote:
>
> Hi Pavel,
>
> I would appreciate if you could send the feedback for the patch.

I will study it today.

Pavel

>
> Thanks!
> Masa
>
> On 08/24/2018 04:29 AM, Michal Hocko wrote:
> > On Fri 24-08-18 00:03:25, Naoya Horiguchi wrote:
> >> (CCed related people)
> >
> > Fixup Pavel email.
> >
> >>
> >> Hi Mizuma-san,
> >>
> >> Thank you for the report.
> >> The mentioned patch was created based on feedbacks from reviewers/maintainers,
> >> so I'd like to hear from them about how we should handle the issue.
> >>
> >> And one note is that there is a follow-up patch for "x86/e820: put !E820_TYPE_RAM
> >> regions into memblock.reserved" which might be affected by your changes.
> >>
> >>> commit e181ae0c5db9544de9c53239eb22bc012ce75033
> >>> Author: Pavel Tatashin <pasha.tatashin@...cle.com>
> >>> Date:   Sat Jul 14 09:15:07 2018 -0400
> >>>
> >>>     mm: zero unavailable pages before memmap init
> >>
> >> Thanks,
> >> Naoya Horiguchi
> >>
> >> On Thu, Aug 23, 2018 at 02:25:12PM -0400, Masayoshi Mizuma wrote:
> >>> From: Masayoshi Mizuma <m.mizuma@...fujitsu.com>
> >>>
> >>> commit 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into
> >>> memblock.reserved") breaks movable_node kernel option because it
> >>> changed the memory gap range to reserved memblock. So, the node
> >>> is marked as Normal zone even if the SRAT has Hot plaggable affinity.
> >>>
> >>>     =====================================================================
> >>>     kernel: BIOS-e820: [mem 0x0000180000000000-0x0000180fffffffff] usable
> >>>     kernel: BIOS-e820: [mem 0x00001c0000000000-0x00001c0fffffffff] usable
> >>>     ...
> >>>     kernel: reserved[0x12]#011[0x0000181000000000-0x00001bffffffffff], 0x000003f000000000 bytes flags: 0x0
> >>>     ...
> >>>     kernel: ACPI: SRAT: Node 2 PXM 6 [mem 0x180000000000-0x1bffffffffff] hotplug
> >>>     kernel: ACPI: SRAT: Node 3 PXM 7 [mem 0x1c0000000000-0x1fffffffffff] hotplug
> >>>     ...
> >>>     kernel: Movable zone start for each node
> >>>     kernel:  Node 3: 0x00001c0000000000
> >>>     kernel: Early memory node ranges
> >>>     ...
> >>>     =====================================================================
> >>>
> >>> Naoya's v1 patch [*] fixes the original issue and this movable_node
> >>> issue doesn't occur.
> >>> Let's revert commit 124049decbb1 ("x86/e820: put !E820_TYPE_RAM
> >>> regions into memblock.reserved") and apply the v1 patch.
> >>>
> >>> [*] https://lkml.org/lkml/2018/6/13/27
> >>>
> >>> Signed-off-by: Masayoshi Mizuma <m.mizuma@...fujitsu.com>
> >>> ---
> >>>  arch/x86/kernel/e820.c | 15 +++------------
> >>>  1 file changed, 3 insertions(+), 12 deletions(-)
> >>>
> >>> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> >>> index c88c23c658c1..d1f25c831447 100644
> >>> --- a/arch/x86/kernel/e820.c
> >>> +++ b/arch/x86/kernel/e820.c
> >>> @@ -1248,7 +1248,6 @@ void __init e820__memblock_setup(void)
> >>>  {
> >>>     int i;
> >>>     u64 end;
> >>> -   u64 addr = 0;
> >>>
> >>>     /*
> >>>      * The bootstrap memblock region count maximum is 128 entries
> >>> @@ -1265,21 +1264,13 @@ void __init e820__memblock_setup(void)
> >>>             struct e820_entry *entry = &e820_table->entries[i];
> >>>
> >>>             end = entry->addr + entry->size;
> >>> -           if (addr < entry->addr)
> >>> -                   memblock_reserve(addr, entry->addr - addr);
> >>> -           addr = end;
> >>>             if (end != (resource_size_t)end)
> >>>                     continue;
> >>>
> >>> -           /*
> >>> -            * all !E820_TYPE_RAM ranges (including gap ranges) are put
> >>> -            * into memblock.reserved to make sure that struct pages in
> >>> -            * such regions are not left uninitialized after bootup.
> >>> -            */
> >>>             if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN)
> >>> -                   memblock_reserve(entry->addr, entry->size);
> >>> -           else
> >>> -                   memblock_add(entry->addr, entry->size);
> >>> +                   continue;
> >>> +
> >>> +           memblock_add(entry->addr, entry->size);
> >>>     }
> >>>
> >>>     /* Throw away partial pages: */
> >>> --
> >>> 2.18.0
> >>>
> >>>
> >
>