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

From: Christophe Leroy
Date: Thu Jan 31 2019 - 01:15:32 EST




Le 31/01/2019 à 07:06, Stephen Rothwell a écrit :
Hi all,

On Thu, 31 Jan 2019 16:38:54 +1100 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Reviewed-by: Guo Ren <ren_guo@xxxxxxxxx> [c-sky]
Acked-by: Paul Burton <paul.burton@xxxxxxxx> [MIPS]
Acked-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> [s390]
Reviewed-by: Juergen Gross <jgross@xxxxxxxx> [Xen]
Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> [m68k]
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Greentime Hu <green.hu@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Guan Xuetao <gxt@xxxxxxxxxx>
Cc: Guo Ren <guoren@xxxxxxxxxx>
Cc: Mark Salter <msalter@xxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Stafford Horne <shorne@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

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.


No I think the error is really in that patch, see my other mail.

See https://elixir.bootlin.com/linux/v5.0-rc4/source/mm/memblock.c#L1455, memblock_alloc_try_nid_raw() is not supposed to panic, so the last hunk of this patch should be reverted.

Found in total three problematic hunks in that patch:

@@ -48,6 +53,11 @@ static phys_addr_t __init kasan_alloc_raw_page(int node)
void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE,
__pa(MAX_DMA_ADDRESS),
MEMBLOCK_ALLOC_KASAN, node);
+ if (!p)
+ panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
+ __func__, PAGE_SIZE, PAGE_SIZE, node,
+ __pa(MAX_DMA_ADDRESS));
+
return __pa(p);
}

@@ -211,6 +211,9 @@ static int __init iob_init(struct device_node *dn)
iob_l2_base = memblock_alloc_try_nid_raw(1UL << 21, 1UL << 21,
MEMBLOCK_LOW_LIMIT, 0x80000000,
NUMA_NO_NODE);
+ if (!iob_l2_base)
+ panic("%s: Failed to allocate %lu bytes align=0x%lx max_addr=%x\n",
+ __func__, 1UL << 21, 1UL << 21, 0x80000000);

pr_info("IOBMAP L2 allocated at: %p\n", iob_l2_base);


@@ -425,6 +436,10 @@ static void __init sparse_buffer_init(unsigned long size, int nid)
memblock_alloc_try_nid_raw(size, PAGE_SIZE,
__pa(MAX_DMA_ADDRESS),
MEMBLOCK_ALLOC_ACCESSIBLE, nid);
+ if (!sparsemap_buf)
+ panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%lx\n",
+ __func__, size, PAGE_SIZE, nid, __pa(MAX_DMA_ADDRESS));
+
sparsemap_buf_end = sparsemap_buf + size;
}



Christophe