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Subject[PATCHv2 0/3] mm: bugfix for NULL reference in mm on all archs
This bug is original reported at
In a short word, this bug should affect all archs, where a machine with a
numa-node having no memory, if nr_cpus prevents the instance of nodeA, and the
device on nodeA tries to allocate memory with device->numa_node info.
And node_zonelist(preferred_nid, gfp_mask) will panic due to uninstanced nodeA.

And there are two alternative methods to fix it.
-1st. Fix it in mm system
-2nd. Fix it in all archs independently, by online all possible nodes.

Originaly, I tries to fix it by the 1st method, while Michal suggests the 2nd one.
This series [1-2/3] tries to resolve some defect in v1, pointed out by Michal.
For discussion purpose, I send [3/3] in this thread, which tries to show e.g of
the 2nd method on powerpc platform.
For x86, I still help Michal to verify his patch on my test machine, please see:

It has already cost a little long time to find a solution, cc x86 and ppc mailing list
and hope their maintainers to give some suggestion to speed up the final solution.

Pingfan Liu (3):
mm/numa: change the topo of build_zonelist_xx()
mm/numa: build zonelist when alloc for device on offline node
powerpc/numa: make all possible node be instanced against NULL
reference in node_zonelist()

arch/powerpc/mm/numa.c | 13 ++++++--
include/linux/gfp.h | 10 +++++-
mm/page_alloc.c | 85 ++++++++++++++++++++++++++++++++++++--------------
3 files changed, 81 insertions(+), 27 deletions(-)

Cc: Andrew Morton <>
Cc: Michal Hocko <>
Cc: Vlastimil Babka <>
Cc: Mike Rapoport <>
Cc: Bjorn Helgaas <>
Cc: Jonathan Cameron <>
Cc: David Rientjes <>
Cc: Thomas Gleixner <>
Cc: Ingo Molnar <>
Cc: Borislav Petkov <>
Cc: "H. Peter Anvin" <>
Cc: Benjamin Herrenschmidt <>
Cc: Paul Mackerras <>
Cc: Michael Ellerman <>

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