Subject: Re: [BUG] 2.6.25-rc8-mm1 kernel panic while bootup on powerpc

From: Andy Whitcroft <[email-masked]>
Date: Fri, 4 Apr 2008 10:24:22 +0100

On Tue, Apr 01, 2008 at 11:39:09PM -0700, Andrew Morton wrote:
> On Wed, 02 Apr 2008 11:55:36 +0530 Kamalesh Babulal <[email-masked]> wrote:
> 
> > Hi Andrew,
> > 
> > The 2.6.25-rc8-mm1 kernel panic's while bootup on the power machine(s).
> > 
> > [    0.000000] ------------[ cut here ]------------
> > [    0.000000] kernel BUG at arch/powerpc/mm/init_64.c:240!
> > [    0.000000] Oops: Exception in kernel mode, sig: 5 [#1]
> > [    0.000000] SMP NR_CPUS=32 NUMA PowerMac
> > [    0.000000] Modules linked in:
> > [    0.000000] NIP: c0000000003d1dcc LR: c0000000003d1dc4 CTR: c00000000002b6ac
> > [    0.000000] REGS: c00000000049b960 TRAP: 0700   Not tainted  (2.6.25-rc8-mm1-autokern1)
> > [    0.000000] MSR: 9000000000021032 <ME,IR,DR>  CR: 44000088  XER: 20000000
> > [    0.000000] TASK = c0000000003f9c90[0] 'swapper' THREAD: c000000000498000 CPU: 0
> > [    0.000000] GPR00: c0000000003d1dc4 c00000000049bbe0 c0000000004989d0 0000000000000001 
> > [    0.000000] GPR04: d59aca40f0000000 000000000b000000 0000000000000010 0000000000000000 
> > [    0.000000] GPR08: 0000000000000004 0000000000000001 c00000027e520800 c0000000004bf0f0 
> > [    0.000000] GPR12: c0000000004bf020 c0000000003fa900 0000000000000000 0000000000000000 
> > [    0.000000] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
> > [    0.000000] GPR20: 0000000000000000 0000000000000000 0000000000000000 4000000001400000 
> > [    0.000000] GPR24: 00000000017d64b0 c0000000003d6250 0000000000000000 c000000000504000 
> > [    0.000000] GPR28: 0000000000000000 cf000000001f8000 0000000001000000 cf00000000000000 
> > [    0.000000] NIP [c0000000003d1dcc] .vmemmap_populate+0xb8/0xf4
> > [    0.000000] LR [c0000000003d1dc4] .vmemmap_populate+0xb0/0xf4
> > [    0.000000] Call Trace:
> > [    0.000000] [c00000000049bbe0] [c0000000003d1dc4] .vmemmap_populate+0xb0/0xf4 (unreliable)
> > [    0.000000] [c00000000049bc70] [c0000000003d2ee8] .sparse_mem_map_populate+0x38/0x60
> > [    0.000000] [c00000000049bd00] [c0000000003c242c] .sparse_early_mem_map_alloc+0x54/0x94
> > [    0.000000] [c00000000049bd90] [c0000000003c250c] .sparse_init+0xa0/0x20c
> > [    0.000000] [c00000000049be50] [c0000000003ab7d0] .setup_arch+0x1ac/0x218
> > [    0.000000] [c00000000049bee0] [c0000000003a36ac] .start_kernel+0xe0/0x3fc
> > [    0.000000] [c00000000049bf90] [c000000000008594] .start_here_common+0x54/0xc0
> > [    0.000000] Instruction dump:
> > [    0.000000] 7fe3fb78 7ca02a14 4082000c 3860fff4 4800003c e92289c8 e96289c0 e9090002 
> > [    0.000000] e8eb0002 4bc575cd 60000000 78630fe0 <0b030000> 7ffff214 7fbfe840 7fe3fb78 
> > [    0.000000] ---[ end trace 31fd0ba7d8756001 ]---
> > [    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
> > 
> 
> int __meminit vmemmap_populate(struct page *start_page,
> 					unsigned long nr_pages, int node)
> {
> 	unsigned long mode_rw;
> 	unsigned long start = (unsigned long)start_page;
> 	unsigned long end = (unsigned long)(start_page + nr_pages);
> 	unsigned long page_size = 1 << mmu_psize_defs[mmu_linear_psize].shift;
> 
> 	mode_rw = _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_COHERENT | PP_RWXX;
> 
> 	/* Align to the page size of the linear mapping. */
> 	start = _ALIGN_DOWN(start, page_size);
> 
> 	for (; start < end; start += page_size) {
> 		int mapped;
> 		void *p;
> 
> 		if (vmemmap_populated(start, page_size))
> 			continue;
> 
> 		p = vmemmap_alloc_block(page_size, node);
> 		if (!p)
> 			return -ENOMEM;
> 
> 		pr_debug("vmemmap %08lx allocated at %p, physical %08lx.\n",
> 			start, p, __pa(p));
> 
> 		mapped = htab_bolt_mapping(start, start + page_size,
> 					__pa(p), mode_rw, mmu_linear_psize,
> 					mmu_kernel_ssize);
> =====>		BUG_ON(mapped < 0);
> 	}
> 
> 	return 0;
> }
> 
> Beats me.  pseries?  Badari has been diddling with the bolted memory code
> in git-powerpc...

It does look like this is resolved with the patch below, if my testing
is to be believed (results out on TKO):

    [PATCH] mm: allocate usemap at first instead of mem_map in sparse_init
    From: Yinghai Lu <[email-masked]>

Andrew, I believe you just sucked that up into -mm.

-apw