linux/mm
Mikulas Patocka 627240aaa9 bootmem allocator: alloc_bootmem_core(): page-align the end offset
This is the minimal sequence that jams the allocator:

void *p, *q, *r;
p = alloc_bootmem(PAGE_SIZE);
q = alloc_bootmem(64);
free_bootmem(p, PAGE_SIZE);
p = alloc_bootmem(PAGE_SIZE);
r = alloc_bootmem(64);

after this sequence (assuming that the allocator was empty or page-aligned
before), pointer "q" will be equal to pointer "r".

What's hapenning inside the allocator:
p = alloc_bootmem(PAGE_SIZE);
in allocator: last_end_off == PAGE_SIZE, bitmap contains bits 10000...
q = alloc_bootmem(64);
in allocator: last_end_off == PAGE_SIZE + 64, bitmap contains 11000...
free_bootmem(p, PAGE_SIZE);
in allocator: last_end_off == PAGE_SIZE + 64, bitmap contains 01000...
p = alloc_bootmem(PAGE_SIZE);
in allocator: last_end_off == PAGE_SIZE, bitmap contains 11000...
r = alloc_bootmem(64);

and now:

it finds bit "2", as a place where to allocate (sidx)

it hits the condition

if (bdata->last_end_off && PFN_DOWN(bdata->last_end_off) + 1 == sidx))
start_off = ALIGN(bdata->last_end_off, align);

-you can see that the condition is true, so it assigns start_off =
ALIGN(bdata->last_end_off, align); (that is PAGE_SIZE) and allocates
over already allocated block.

With the patch it tries to continue at the end of previous allocation only
if the previous allocation ended in the middle of the page.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Johannes Weiner <hannes@saeurebad.de>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-15 08:35:41 -07:00
..
allocpercpu.c mm/allocpercpu.c: make 4 functions static 2008-07-26 12:00:12 -07:00
backing-dev.c mm: bdi: fix race in bdi_class device creation 2008-05-20 13:31:53 -07:00
bootmem.c bootmem allocator: alloc_bootmem_core(): page-align the end offset 2008-08-15 08:35:41 -07:00
bounce.c block: Initial support for data-less (or empty) barrier support 2007-10-16 11:03:56 +02:00
dmapool.c dmapool: enable debugging for CONFIG_SLUB_DEBUG_ON too 2008-04-28 08:58:20 -07:00
fadvise.c xip: support non-struct page backed memory 2008-04-28 08:58:23 -07:00
filemap_xip.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
filemap.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
fremap.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
highmem.c highmem: Export totalhigh_pages. 2008-07-19 22:39:46 -07:00
hugetlb.c allocate structures for reservation tracking in hugetlbfs outside of spinlocks v2 2008-08-12 16:07:28 -07:00
internal.h mm: export prep_compound_page to mm 2008-07-24 10:47:17 -07:00
Kconfig mm: Make generic weak get_user_pages_fast and EXPORT_GPL it 2008-08-12 17:52:53 +10:00
maccess.c kgdb: fix optional arch functions and probe_kernel_* 2008-04-17 20:05:39 +02:00
madvise.c madvise: update function comment of madvise_dontneed 2008-07-30 09:41:45 -07:00
Makefile mmu-notifiers: core 2008-07-28 16:30:21 -07:00
memcontrol.c memcg: fix oops in mem_cgroup_shrink_usage 2008-08-12 16:07:28 -07:00
memory_hotplug.c memory-hotplug: add sysfs removable attribute for hotplug memory remove 2008-07-24 10:47:21 -07:00
memory.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
mempolicy.c do_migrate_pages(): remove unused variable 2008-08-12 16:07:29 -07:00
mempool.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
migrate.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
mincore.c mm: remove nopage 2008-04-28 08:58:18 -07:00
mlock.c mlock() fix return values 2008-08-04 16:58:45 -07:00
mm_init.c mm_init.c: avoid ifdef-inside-macro-expansion 2008-08-05 14:33:46 -07:00
mmap.c Merge branch 'core/locking' into core/urgent 2008-08-12 00:11:49 +02:00
mmu_notifier.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
mmzone.c mm: filter based on a nodemask as well as a gfp_mask 2008-04-28 08:58:19 -07:00
mprotect.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
mremap.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
msync.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
nommu.c nommu: Provide vmalloc_exec(). 2008-08-04 16:01:47 +09:00
oom_kill.c oom_kill: remove unused parameter in badness() 2008-04-28 08:58:26 -07:00
page_alloc.c page allocator: use no-panic variant of alloc_bootmem() in alloc_large_system_hash() 2008-08-12 16:07:27 -07:00
page_io.c mm: fix PageUptodate data race 2008-02-05 09:44:19 -08:00
page_isolation.c memory hotremove: unset migrate type "ISOLATE" after removal 2007-11-14 18:45:38 -08:00
page-writeback.c mm: spinlock tree_lock 2008-07-26 12:00:06 -07:00
pagewalk.c pagemap: pass mm into pagewalkers 2008-06-12 18:05:41 -07:00
pdflush.c pdflush: use time_after() instead of open-coding it 2008-07-25 10:53:28 -07:00
prio_tree.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
quicklist.c quicklists: Only consider memory that can be used with GFP_KERNEL 2008-01-14 08:52:22 -08:00
readahead.c mm: readahead scan lockless 2008-07-26 12:00:06 -07:00
rmap.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
shmem_acl.c [PATCH] sanitize ->permission() prototype 2008-07-26 20:53:14 -04:00
shmem.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
slab.c mm: unexport ksize 2008-07-29 23:44:26 +03:00
slob.c mm: unexport ksize 2008-07-29 23:44:26 +03:00
slub.c SLUB: dynamic per-cache MIN_PARTIAL 2008-08-05 09:28:47 +03:00
sparse-vmemmap.c Christoph has moved 2008-07-04 10:40:04 -07:00
sparse.c mm/sparse.c: removed duplicated include 2008-08-12 16:07:30 -07:00
swap_state.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
swap.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
swapfile.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
thrash.c Bug in mm/thrash.c function grab_swap_token() 2007-05-11 08:29:32 -07:00
tiny-shmem.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2008-03-25 08:57:47 -07:00
truncate.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
util.c mm: Make generic weak get_user_pages_fast and EXPORT_GPL it 2008-08-12 17:52:53 +10:00
vmalloc.c Use WARN() in mm/vmalloc.c 2008-07-26 12:00:07 -07:00
vmscan.c mm: rename page trylock 2008-08-04 21:31:34 -07:00
vmstat.c mm/vmstat.c: proper externs 2008-07-24 10:47:14 -07:00