Re: linux-next: powerpc le qemu boot failure after merge of the akpm tree

Hi all,

On Thu, 31 Jan 2019 16:38:54 +1100 Stephen Rothwell [off-list ref] 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 [off-list ref]
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 [off-list ref]
    Reviewed-by: Guo Ren [off-list ref]                [c-sky]
    Acked-by: Paul Burton [off-list ref]            [MIPS]
    Acked-by: Heiko Carstens [off-list ref]    [s390]
    Reviewed-by: Juergen Gross [off-list ref]            [Xen]
    Reviewed-by: Geert Uytterhoeven [off-list ref]  [m68k]
    Cc: Catalin Marinas [off-list ref]
    Cc: Christophe Leroy [off-list ref]
    Cc: Christoph Hellwig [off-list ref]
    Cc: "David S. Miller" [off-list ref]
    Cc: Dennis Zhou [off-list ref]
    Cc: Greentime Hu [off-list ref]
    Cc: Greg Kroah-Hartman [off-list ref]
    Cc: Guan Xuetao [off-list ref]
    Cc: Guo Ren [off-list ref]
    Cc: Mark Salter [off-list ref]
    Cc: Matt Turner [off-list ref]
    Cc: Max Filippov [off-list ref]
    Cc: Michael Ellerman [off-list ref]
    Cc: Michal Simek [off-list ref]
    Cc: Petr Mladek [off-list ref]
    Cc: Richard Weinberger [off-list ref]
    Cc: Rich Felker [off-list ref]
    Cc: Rob Herring [off-list ref]
    Cc: Rob Herring [off-list ref]
    Cc: Russell King [off-list ref]
    Cc: Stafford Horne [off-list ref]
    Cc: Tony Luck [off-list ref]
    Cc: Vineet Gupta [off-list ref]
    Cc: Yoshinori Sato [off-list ref]
    Signed-off-by: Andrew Morton [off-list ref]

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