Hi all,

On Thu, 31 Jan 2019 16:38:54 +1100 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> [I am guessing that is is something in Andrew's tree that has caused
> this.]
> 
> My qemu boot of the powerpc pseries_le_defconfig config failed like this:
> 
> htab_hash_mask    = 0x1ffff
> -----------------------------------------------------
> numa:   NODE_DATA [mem 0x7ffe7000-0x7ffebfff]
> Kernel panic - not syncing: sparse_buffer_init: Failed to allocate 2147483648 bytes align=0x10000 nid=0 from=fffffffffffffff
> CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc4 #2
> Call Trace:
> [c00000000105bbd0] [c000000000b1345c] dump_stack+0xb0/0xf4 (unreliable)
> [c00000000105bc10] [c000000000111120] panic+0x168/0x3b8
> [c00000000105bcb0] [c000000000e701c8] sparse_init_nid+0x178/0x550
> [c00000000105bd70] [c000000000e709b4] sparse_init+0x210/0x238
> [c00000000105bdb0] [c000000000e468f4] initmem_init+0x1e0/0x260
> [c00000000105be80] [c000000000e3b9b0] setup_arch+0x354/0x3d4
> [c00000000105bef0] [c000000000e33afc] start_kernel+0x98/0x648
> [c00000000105bf90] [c00000000000b270] start_here_common+0x1c/0x52c

A quick bisect leads to this:

1c3c9328cde027eb875ba4692f0a5d66b0afe862 is the first bad commit
commit 1c3c9328cde027eb875ba4692f0a5d66b0afe862
Author: Mike Rapoport <rppt@linux.ibm.com>
Date:   Thu Jan 31 10:51:32 2019 +1100

    treewide: add checks for the return value of memblock_alloc*()
    
    Add check for the return value of memblock_alloc*() functions and call
    panic() in case of error.  The panic message repeats the one used by
    panicing memblock allocators with adjustment of parameters to include only
    relevant ones.
    
    The replacement was mostly automated with semantic patches like the one
    below with manual massaging of format strings.
    
    @@
    expression ptr, size, align;
    @@
    ptr = memblock_alloc(size, align);
    + if (!ptr)
    +       panic("%s: Failed to allocate %lu bytes align=0x%lx\n", __func__,
    size, align);
    
    Link: http://lkml.kernel.org/r/1548057848-15136-20-git-send-email-rppt@linux.ibm.com
    Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
    Reviewed-by: Guo Ren <ren_guo@c-sky.com>                [c-sky]
    Acked-by: Paul Burton <paul.burton@mips.com>            [MIPS]
    Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>    [s390]
    Reviewed-by: Juergen Gross <jgross@suse.com>            [Xen]
    Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>  [m68k]
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Christophe Leroy <christophe.leroy@c-s.fr>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Dennis Zhou <dennis@kernel.org>
    Cc: Greentime Hu <green.hu@gmail.com>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Guan Xuetao <gxt@pku.edu.cn>
    Cc: Guo Ren <guoren@kernel.org>
    Cc: Mark Salter <msalter@redhat.com>
    Cc: Matt Turner <mattst88@gmail.com>
    Cc: Max Filippov <jcmvbkbc@gmail.com>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Michal Simek <monstr@monstr.eu>
    Cc: Petr Mladek <pmladek@suse.com>
    Cc: Richard Weinberger <richard@nod.at>
    Cc: Rich Felker <dalias@libc.org>
    Cc: Rob Herring <robh+dt@kernel.org>
    Cc: Rob Herring <robh@kernel.org>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Stafford Horne <shorne@gmail.com>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Vineet Gupta <vgupta@synopsys.com>
    Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Which is just adding the panic we hit.  So, presumably, the bug is in a
preceding patch :-(

I have left the kernel not booting for today.
-- 
Cheers,
Stephen Rothwell