From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Max Filippov , Gavin Shan , Johannes Weiner , Tejun Heo , Yinghai Lu , Joonsoo Kim , Prasad Koya , Andrew Morton , Linus Torvalds Subject: [ 018/221] mm: bootmem: fix free_all_bootmem_core() with odd bitmap alignment Date: Tue, 15 Jan 2013 10:49:05 -0800 Message-Id: <20130115184959.369708102@linuxfoundation.org> In-Reply-To: <20130115184958.025580322@linuxfoundation.org> References: <20130115184958.025580322@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Max Filippov commit 10d73e655cef6e86ea8589dca3df4e495e4900b0 upstream. 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 Cc: Gavin Shan Cc: Johannes Weiner Cc: Tejun Heo Cc: Yinghai Lu Cc: Joonsoo Kim Cc: Prasad Koya Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/bootmem.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -185,10 +185,23 @@ static unsigned long __init free_all_boo 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_boo 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); } }