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SubjectRe: [PATCH] Revert "mm/page_alloc: fix memmap_init_zone pageblock alignment"
Does http://lkml.kernel.org/r/20180313224240.25295-1-neelx@redhat.com
fix your issue? From the debugging info you provided it should because
the patch prevents jumping backwards.

On Wed 14-03-18 13:44:31, Ard Biesheuvel wrote:
> This reverts commit 864b75f9d6b0100bb24fdd9a20d156e7cda9b5ae.
>
> It breaks the boot on my Socionext SynQuacer based system, because
> it enters an infinite loop iterating over the pfns.
>
> Adding the following debug output to memmap_init_zone()
>
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5365,6 +5365,11 @@
> * the valid region but still depends on correct page
> * metadata.
> */
> + pr_err("pfn:%lx oldnext:%lx newnext:%lx\n", pfn,
> + memblock_next_valid_pfn(pfn, end_pfn) - 1,
> + (memblock_next_valid_pfn(pfn, end_pfn) &
> + ~(pageblock_nr_pages-1)) - 1);
> +
> pfn = (memblock_next_valid_pfn(pfn, end_pfn) &
> ~(pageblock_nr_pages-1)) - 1;
> #endif
>
> results in
>
> Booting Linux on physical CPU 0x0000000000 [0x410fd034]
> Linux version 4.16.0-rc5-00004-gfc6eabbbf8ef-dirty (ard@dogfood) ...
> Machine model: Socionext Developer Box
> earlycon: pl11 at MMIO 0x000000002a400000 (options '')
> bootconsole [pl11] enabled
> efi: Getting EFI parameters from FDT:
> efi: EFI v2.70 by Linaro
> efi: SMBIOS 3.0=0xff580000 ESRT=0xf9948198 MEMATTR=0xf83b1a98 RNG=0xff7ac898
> random: fast init done
> efi: seeding entropy pool
> esrt: Reserving ESRT space from 0x00000000f9948198 to 0x00000000f99481d0.
> cma: Reserved 16 MiB at 0x00000000fd800000
> NUMA: No NUMA configuration found
> NUMA: Faking a node at [mem 0x0000000000000000-0x0000000fffffffff]
> NUMA: NODE_DATA [mem 0xffffd8d80-0xffffda87f]
> Zone ranges:
> DMA32 [mem 0x0000000080000000-0x00000000ffffffff]
> Normal [mem 0x0000000100000000-0x0000000fffffffff]
> Movable zone start for each node
> Early memory node ranges
> node 0: [mem 0x0000000080000000-0x00000000febeffff]
> node 0: [mem 0x00000000febf0000-0x00000000fefcffff]
> node 0: [mem 0x00000000fefd0000-0x00000000ff43ffff]
> node 0: [mem 0x00000000ff440000-0x00000000ff7affff]
> node 0: [mem 0x00000000ff7b0000-0x00000000ffffffff]
> node 0: [mem 0x0000000880000000-0x0000000fffffffff]
> Initmem setup node 0 [mem 0x0000000080000000-0x0000000fffffffff]
> pfn:febf0 oldnext:febf0 newnext:fe9ff
> pfn:febf0 oldnext:febf0 newnext:fe9ff
> pfn:febf0 oldnext:febf0 newnext:fe9ff
> etc etc
>
> and the boot never proceeds after this point.
>
> So the logic is obviously flawed, and so it is best to revert this at
> the current -rc stage (unless someone can fix the logic instead)
>
> Fixes: 864b75f9d6b0 ("mm/page_alloc: fix memmap_init_zone pageblock alignment")
> Cc: Daniel Vacek <neelx@redhat.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Paul Burton <paul.burton@imgtec.com>
> Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> mm/page_alloc.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3d974cb2a1a1..cb416723538f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5359,14 +5359,9 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
> /*
> * 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. Note that it needs
> - * to be pageblock aligned even when the region itself
> - * is not. move_freepages_block() can shift ahead of
> - * the valid region but still depends on correct page
> - * metadata.
> + * on our next iteration of the loop.
> */
> - pfn = (memblock_next_valid_pfn(pfn, end_pfn) &
> - ~(pageblock_nr_pages-1)) - 1;
> + pfn = memblock_next_valid_pfn(pfn, end_pfn) - 1;
> #endif
> continue;
> }
> --
> 2.15.1
>

--
Michal Hocko
SUSE Labs

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