Messages in this thread | | | From | Johannes Weiner <> | Subject | Re: [PATCH] Fix spurious BUG_ON() in mark_bootmem() | Date | Thu, 10 Jul 2008 00:43:42 +0200 |
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Hi Lee,
Lee Schermerhorn <Lee.Schermerhorn@hp.com> writes:
> Against: 2.6.26-rc8-mm1 > > Fixes problem introduced by patches: > > bootmem-factor-out-the-marking-of-a-pfn-range.patch > bootmem-replace-node_boot_start-in-struct-bootmem_data.patch > > HP ia64 NUMA platform fails to boot 26-rc8-mm1, hitting BUG_ON() > in mm/bootmem.c:mark_bootmem(). > > After linking all bootmem chunks, the 'bdata_list' on HP ia64 numa > platforms looks something like this: > > node 4: 0x0-0x8000 > node 0: 0x1c008000-0x1c07ec00 > node 1: 0x1c800000-0x1c87f000 > node 2: 0x1d000000-0x1d07f000 > node 3: 0x1d800000-0x1d87f000 > > [Node 4 is a pseudo-node generated by the platform firmware to > contain a configurable amount of zero-based, hardware interleaved > memory. 0x8000 pages or 512M is the minimum that can be configured.] > > First call to mark_bootmem() [from free_bootmem()] called with: > > start-end: 0x1c008063-0x1c008262, reserve: 0, flags: 0 > > I.e, NOT in the first chunk of the list. > > However, the "if (pos < bdata->node_min_pfn)" in the loop fails > to test the start address of the argument range [in 'pos'] against > the end of the chunk. So, it treats the range as being in the node > 4 chunk. Second time thru' the loop, pos == 0x8000 is < > bdata->node_min_pfn and pos != start, so we trip the BUG_ON(). > > This patch enhances the if condition to skip chunks that do not > overlap the argument range, allowing 26-rc8-mm1 to boot on this > platform. > > Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> > > mm/bootmem.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > Index: linux-2.6.26-rc8-mm1/mm/bootmem.c > =================================================================== > --- linux-2.6.26-rc8-mm1.orig/mm/bootmem.c 2008-07-09 16:11:23.000000000 -0400 > +++ linux-2.6.26-rc8-mm1/mm/bootmem.c 2008-07-09 16:13:46.000000000 -0400 > @@ -299,7 +299,8 @@ static int __init mark_bootmem(unsigned > int err; > unsigned long max; > > - if (pos < bdata->node_min_pfn) { > + if (pos < bdata->node_min_pfn || > + pos >= bdata->node_low_pfn) { > BUG_ON(pos != start); > continue; > }
Ah, yeah, this was obviously wrong. Thanks for the fix!
Acked-by: Johannes Weiner <hannes@saeurebad.de>
Nice to know that it boots otherwise on such a setup :)
Hannes
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