• James Morse's avatar
    arm64: mm: always enable CONFIG_HOLES_IN_ZONE · 29245d36
    James Morse authored
    commit f52bb98f upstream.
    Commit 6d526ee2 ("arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA")
    only enabled HOLES_IN_ZONE for NUMA systems because the NUMA code was
    choking on the missing zone for nomap pages. This problem doesn't just
    apply to NUMA systems.
    If the architecture doesn't set HAVE_ARCH_PFN_VALID, pfn_valid() will
    return true if the pfn is part of a valid sparsemem section.
    When working with multiple pages, the mm code uses pfn_valid_within()
    to test each page it uses within the sparsemem section is valid. On
    most systems memory comes in MAX_ORDER_NR_PAGES chunks which all
    have valid/initialised struct pages. In this case pfn_valid_within()
    is optimised out.
    Systems where this isn't true (e.g. due to nomap) should set
    HOLES_IN_ZONE and provide HAVE_ARCH_PFN_VALID so that mm tests each
    page as it works with it.
    Currently non-NUMA arm64 systems can't enable HOLES_IN_ZONE, leading to
    a VM_BUG_ON():
    | page:fffffdff802e1780 is uninitialized and poisoned
    | raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
    | raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
    | page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
    | ------------[ cut here ]------------
    | kernel BUG at include/linux/mm.h:978!
    | Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
    | CPU: 1 PID: 25236 Comm: dd Not tainted 4.18.0 #7
    | Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
    | pstate: 40000085 (nZcv daIf -PAN -UAO)
    | pc : move_freepages_block+0x144/0x248
    | lr : move_freepages_block+0x144/0x248
    | sp : fffffe0071177680
    | Process dd (pid: 25236, stack limit = 0x0000000094cc07fb)
    | Call trace:
    |  move_freepages_block+0x144/0x248
    |  steal_suitable_fallback+0x100/0x16c
    |  get_page_from_freelist+0x440/0xb20
    |  __alloc_pages_nodemask+0xe8/0x838
    |  new_slab+0xd4/0x418
    |  ___slab_alloc.constprop.27+0x380/0x4a8
    |  __slab_alloc.isra.21.constprop.26+0x24/0x34
    |  kmem_cache_alloc+0xa8/0x180
    |  alloc_buffer_head+0x1c/0x90
    |  alloc_page_buffers+0x68/0xb0
    |  create_empty_buffers+0x20/0x1ec
    |  create_page_buffers+0xb0/0xf0
    |  __block_write_begin_int+0xc4/0x564
    |  __block_write_begin+0x10/0x18
    |  block_write_begin+0x48/0xd0
    |  blkdev_write_begin+0x28/0x30
    |  generic_perform_write+0x98/0x16c
    |  __generic_file_write_iter+0x138/0x168
    |  blkdev_write_iter+0x80/0xf0
    |  __vfs_write+0xe4/0x10c
    |  vfs_write+0xb4/0x168
    |  ksys_write+0x44/0x88
    |  sys_write+0xc/0x14
    |  el0_svc_naked+0x30/0x34
    | Code: aa1303e0 90001a01 91296421 94008902 (d4210000)
    | ---[ end trace 1601ba47f6e883fe ]---
    Remove the NUMA dependency.
    Link: https://www.spinics.net/lists/arm-kernel/msg671851.html
    Cc: <stable@vger.kernel.org>
    Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Reported-by: default avatarMikulas Patocka <mpatocka@redhat.com>
    Reviewed-by: default avatarPavel Tatashin <pavel.tatashin@microsoft.com>
    Tested-by: default avatarMikulas Patocka <mpatocka@redhat.com>
    Signed-off-by: default avatarJames Morse <james.morse@arm.com>
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Kconfig 36.2 KB