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author | Nishanth Aravamudan <nacc@linux.vnet.ibm.com> | 2012-03-22 00:34:07 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-22 01:54:58 +0100 |
commit | f5bf18fa22f8c41a13eb8762c7373eb3a93a7333 (patch) | |
tree | 3da24eb0edae3563c1937088b72a413e7026fdec /mm/bootmem.c | |
parent | mm: drain percpu lru add/rotate page-vectors on cpu hot-unplug (diff) | |
download | linux-f5bf18fa22f8c41a13eb8762c7373eb3a93a7333.tar.xz linux-f5bf18fa22f8c41a13eb8762c7373eb3a93a7333.zip |
bootmem/sparsemem: remove limit constraint in alloc_bootmem_section
While testing AMS (Active Memory Sharing) / CMO (Cooperative Memory
Overcommit) on powerpc, we tripped the following:
kernel BUG at mm/bootmem.c:483!
cpu 0x0: Vector: 700 (Program Check) at [c000000000c03940]
pc: c000000000a62bd8: .alloc_bootmem_core+0x90/0x39c
lr: c000000000a64bcc: .sparse_early_usemaps_alloc_node+0x84/0x29c
sp: c000000000c03bc0
msr: 8000000000021032
current = 0xc000000000b0cce0
paca = 0xc000000001d80000
pid = 0, comm = swapper
kernel BUG at mm/bootmem.c:483!
enter ? for help
[c000000000c03c80] c000000000a64bcc
.sparse_early_usemaps_alloc_node+0x84/0x29c
[c000000000c03d50] c000000000a64f10 .sparse_init+0x12c/0x28c
[c000000000c03e20] c000000000a474f4 .setup_arch+0x20c/0x294
[c000000000c03ee0] c000000000a4079c .start_kernel+0xb4/0x460
[c000000000c03f90] c000000000009670 .start_here_common+0x1c/0x2c
This is
BUG_ON(limit && goal + size > limit);
and after some debugging, it seems that
goal = 0x7ffff000000
limit = 0x80000000000
and sparse_early_usemaps_alloc_node ->
sparse_early_usemaps_alloc_pgdat_section calls
return alloc_bootmem_section(usemap_size() * count, section_nr);
This is on a system with 8TB available via the AMS pool, and as a quirk
of AMS in firmware, all of that memory shows up in node 0. So, we end
up with an allocation that will fail the goal/limit constraints.
In theory, we could "fall-back" to alloc_bootmem_node() in
sparse_early_usemaps_alloc_node(), but since we actually have HOTREMOVE
defined, we'll BUG_ON() instead. A simple solution appears to be to
unconditionally remove the limit condition in alloc_bootmem_section,
meaning allocations are allowed to cross section boundaries (necessary
for systems of this size).
Johannes Weiner pointed out that if alloc_bootmem_section() no longer
guarantees section-locality, we need check_usemap_section_nr() to print
possible cross-dependencies between node descriptors and the usemaps
allocated through it. That makes the two loops in
sparse_early_usemaps_alloc_node() identical, so re-factor the code a
bit.
[akpm@linux-foundation.org: code simplification]
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Anton Blanchard <anton@au1.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org> [3.3.1]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/bootmem.c')
-rw-r--r-- | mm/bootmem.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/bootmem.c b/mm/bootmem.c index 668e94df8cf2..0131170c9d54 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -766,14 +766,13 @@ void * __init alloc_bootmem_section(unsigned long size, unsigned long section_nr) { bootmem_data_t *bdata; - unsigned long pfn, goal, limit; + unsigned long pfn, goal; pfn = section_nr_to_pfn(section_nr); goal = pfn << PAGE_SHIFT; - limit = section_nr_to_pfn(section_nr + 1) << PAGE_SHIFT; bdata = &bootmem_node_data[early_pfn_to_nid(pfn)]; - return alloc_bootmem_core(bdata, size, SMP_CACHE_BYTES, goal, limit); + return alloc_bootmem_core(bdata, size, SMP_CACHE_BYTES, goal, 0); } #endif |