diff options
author | Max Filippov <jcmvbkbc@gmail.com> | 2013-01-11 23:31:52 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-01-11 23:54:55 +0100 |
commit | 10d73e655cef6e86ea8589dca3df4e495e4900b0 (patch) | |
tree | a6bb3c7f80ec2a4b7eb65e714d6fe4426be26fcc /mm | |
parent | mm: use aligned zone start for pfn_to_bitidx calculation (diff) | |
download | linux-10d73e655cef6e86ea8589dca3df4e495e4900b0.tar.xz linux-10d73e655cef6e86ea8589dca3df4e495e4900b0.zip |
mm: bootmem: fix free_all_bootmem_core() with odd bitmap alignment
Currently free_all_bootmem_core ignores that node_min_pfn may be not
multiple of BITS_PER_LONG. Eg commit 6dccdcbe2c3e ("mm: bootmem: fix
checking the bitmap when finally freeing bootmem") shifts vec by lower
bits of start instead of lower bits of idx. Also
if (IS_ALIGNED(start, BITS_PER_LONG) && vec == ~0UL)
assumes that vec bit 0 corresponds to start pfn, which is only true when
node_min_pfn is a multiple of BITS_PER_LONG. Also loop in the else
clause can double-free pages (e.g. with node_min_pfn == start == 1,
map[0] == ~0 on 32-bit machine page 32 will be double-freed).
This bug causes the following message during xtensa kernel boot:
bootmem::free_all_bootmem_core nid=0 start=1 end=8000
BUG: Bad page state in process swapper pfn:00001
page:d04bd020 count:0 mapcount:-127 mapping: (null) index:0x2
page flags: 0x0()
Call Trace:
bad_page+0x8c/0x9c
free_pages_prepare+0x5e/0x88
free_hot_cold_page+0xc/0xa0
__free_pages+0x24/0x38
__free_pages_bootmem+0x54/0x56
free_all_bootmem_core$part$11+0xeb/0x138
free_all_bootmem+0x46/0x58
mem_init+0x25/0xa4
start_kernel+0x11e/0x25c
should_never_return+0x0/0x3be7
The fix is the following:
- always align vec so that its bit 0 corresponds to start
- provide BITS_PER_LONG bits in vec, if those bits are available in the
map
- don't free pages past next start position in the else clause.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Prasad Koya <prasad.koya@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/bootmem.c | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/mm/bootmem.c b/mm/bootmem.c index 1324cd74faec..b93376c39b61 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -185,10 +185,23 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) while (start < end) { unsigned long *map, idx, vec; + unsigned shift; map = bdata->node_bootmem_map; idx = start - bdata->node_min_pfn; + shift = idx & (BITS_PER_LONG - 1); + /* + * vec holds at most BITS_PER_LONG map bits, + * bit 0 corresponds to start. + */ vec = ~map[idx / BITS_PER_LONG]; + + if (shift) { + vec >>= shift; + if (end - start >= BITS_PER_LONG) + vec |= ~map[idx / BITS_PER_LONG + 1] << + (BITS_PER_LONG - shift); + } /* * If we have a properly aligned and fully unreserved * BITS_PER_LONG block of pages in front of us, free @@ -201,19 +214,18 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) count += BITS_PER_LONG; start += BITS_PER_LONG; } else { - unsigned long off = 0; + unsigned long cur = start; - vec >>= start & (BITS_PER_LONG - 1); - while (vec) { + start = ALIGN(start + 1, BITS_PER_LONG); + while (vec && cur != start) { if (vec & 1) { - page = pfn_to_page(start + off); + page = pfn_to_page(cur); __free_pages_bootmem(page, 0); count++; } vec >>= 1; - off++; + ++cur; } - start = ALIGN(start + 1, BITS_PER_LONG); } } |