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Nick Piggin 27d20fddc8 radix-tree: fix RCU bug 
Salman Qazi describes the following radix-tree bug:

In the following case, we get can get a deadlock:

0.  The radix tree contains two items, one has the index 0.
1.  The reader (in this case find_get_pages) takes the rcu_read_lock.
2.  The reader acquires slot(s) for item(s) including the index 0 item.
3.  The non-zero index item is deleted, and as a consequence the other item is
    moved to the root of the tree. The place where it used to be is queued for
    deletion after the readers finish.
3b. The zero item is deleted, removing it from the direct slot, it remains in
    the rcu-delayed indirect node.
4.  The reader looks at the index 0 slot, and finds that the page has 0 ref
    count
5.  The reader looks at it again, hoping that the item will either be freed or
    the ref count will increase. This never happens, as the slot it is looking
    at will never be updated. Also, this slot can never be reclaimed because
    the reader is holding rcu_read_lock and is in an infinite loop.

The fix is to re-use the same "indirect" pointer case that requires a slot
lookup retry into a general "retry the lookup" bit.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Reported-by: Salman Qazi <sqazi@google.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-12 07:55:32 -08:00
..
lzo lib: add support for LZO-compressed kernels 2010-01-11 09:34:04 -08:00
raid6 Move .gitignore from drivers/md to lib/raid6 2010-08-30 17:35:52 +10:00
reed_solomon
zlib_deflate trivial: fix typo "to to" in multiple files 2009-09-21 15:14:55 +02:00
zlib_inflate inflate_fast: sout is already a short so ptr arith was off by one. 2010-03-12 15:52:44 -08:00
.gitignore
argv_split.c tree-wide: convert open calls to remove spaces to skip_spaces() lib function 2009-12-15 08:53:32 -08:00
atomic64_test.c ARM: 6213/1: atomic64_test: add ARM as supported architecture 2010-07-27 10:43:46 +01:00
atomic64.c lib: Fix atomic64_add_unless return value convention 2010-03-01 11:38:46 -08:00
audit.c
bcd.c
bitmap.c lib/bitmap.c: use hex_to_bin() 2010-10-26 16:52:18 -07:00
bitrev.c
btree.c lib/btree: fix possible NULL pointer dereference 2010-05-15 12:48:10 -07:00
bug.c modules: Fix module_bug_list list corruption race 2010-10-05 11:29:27 -07:00
bust_spinlocks.c
check_signature.c
checksum.c lib/checksum: fix one more thinko 2009-11-03 16:06:53 +01:00
cmdline.c
cpu-notifier-error-inject.c fault-injection: add CPU notifier error injection module 2010-05-27 09:12:48 -07:00
cpumask.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
crc7.c
crc16.c
crc32.c revert "crc32: use __BYTE_ORDER macro for endian detection" 2010-05-26 08:19:23 -07:00
crc32defs.h
crc-ccitt.c
crc-itu-t.c
crc-t10dif.c
ctype.c ctype: constify read-only _ctype string 2009-12-15 08:53:32 -08:00
debug_locks.c rcu: Introduce lockdep-based checking to RCU read-side primitives 2010-02-25 09:40:59 +01:00
debugobjects.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 08:17:58 -07:00
dec_and_lock.c
decompress_bunzip2.c lib/decompress_bunzip2.c: fix checkstack warning 2010-08-11 08:59:23 -07:00
decompress_inflate.c lzma/gzip: fix potential oops when input data is truncated 2009-09-24 07:21:05 -07:00
decompress_unlzma.c lzma/gzip: fix potential oops when input data is truncated 2009-09-24 07:21:05 -07:00
decompress_unlzo.c lib: fix the use of LZO to decompress initramfs images 2010-04-24 11:31:25 -07:00
decompress.c Add LZO compression support for initramfs and old-style initrd 2010-01-11 09:34:05 -08:00
devres.c lib/devres.c: fix comment typo 2010-07-11 22:16:32 +02:00
div64.c div64_u64(): improve precision on 32bit platforms 2010-10-26 16:52:19 -07:00
dma-debug.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
dump_stack.c
dynamic_debug.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2010-10-22 19:36:42 -07:00
extable.c
fault-inject.c headers: remove sched.h from interrupt.h 2009-10-11 11:20:58 -07:00
find_last_bit.c
find_next_bit.c
flex_array.c flex_array: add helpers to get and put to make pointers easy to use 2010-08-09 20:45:09 -07:00
gcd.c
gen_crc32table.c crc32: major optimization 2010-05-25 08:07:06 -07:00
genalloc.c genalloc: fix allocation from end of pool 2010-06-29 15:29:30 -07:00
halfmd4.c
hexdump.c lib: introduce common method to convert hex digits 2010-05-25 08:07:05 -07:00
hweight.c x86: Add optimized popcnt variants 2010-04-06 15:52:11 -07:00
idr.c docbook: add idr/ida to kernel-api docbook 2010-10-26 17:40:56 -07:00
inflate.c MN10300: Don't try and #include <linux/slab.h> in lib/inflate.c from bootloader 2010-08-12 09:51:35 -07:00
int_sqrt.c
iomap_copy.c
iomap.c
iommu-helper.c iommu: inline iommu_num_pages 2010-08-09 20:45:05 -07:00
ioremap.c x86, ioremap: Fix incorrect physical address handling in PAE mode 2010-07-09 11:42:03 -07:00
irq_regs.c
is_single_threaded.c
kasprintf.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
Kconfig Merge branch 'async' of macbook:git/btrfs-unstable 2010-08-09 10:36:44 +01:00
Kconfig.debug Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx 2010-10-27 19:04:36 -07:00
Kconfig.kgdb mips,kgdb: kdb low level trap catch and stack trace 2010-05-20 21:04:26 -05:00
Kconfig.kmemcheck
kernel_lock.c bkl: Fixup core_lock fallout 2009-12-14 23:55:33 +01:00
klist.c
kobject_uevent.c kobject_uevent: fix typo in comments 2010-08-23 18:12:46 -07:00
kobject.c kobject: Introduce kset_find_obj_hinted. 2010-10-22 10:16:44 -07:00
kref.c kref: remove kref_set 2010-05-21 09:37:29 -07:00
lcm.c block: Fix overrun in lcm() and move it to lib 2010-03-15 12:47:59 +01:00
libcrc32c.c
list_debug.c list debugging: warn when deleting a deleted entry 2010-08-09 20:45:08 -07:00
list_sort.c lib/list_sort: test: check element addresses 2010-10-26 16:52:19 -07:00
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c
lru_cache.c The DRBD driver 2009-10-01 21:17:49 +02:00
Makefile Merge branch 'async' of macbook:git/btrfs-unstable 2010-08-09 10:36:44 +01:00
nlattr.c
parser.c lib/parser: cleanup match_number() 2010-10-26 16:52:19 -07:00
percpu_counter.c percpu_counter: use this_cpu_ptr() instead of per_cpu_ptr() 2010-10-26 16:52:19 -07:00
plist.c plist: Make plist debugging raw_spinlock aware 2009-12-14 23:55:33 +01:00
prio_heap.c
prio_tree.c
proportions.c
radix-tree.c radix-tree: fix RCU bug 2010-11-12 07:55:32 -08:00
random32.c Merge branch 'master' into for-next 2010-06-16 18:08:13 +02:00
ratelimit.c ratelimit: fix the return value when __ratelimit() fails to acquire the lock 2010-04-07 08:38:04 -07:00
rational.c lib/rational.c needs module.h 2010-01-11 09:34:05 -08:00
rbtree.c rbtree: Undo augmented trees performance damage and regression 2010-07-05 14:43:50 +02:00
reciprocal_div.c
rwsem-spinlock.c rwsem generic spinlock: use IRQ save/restore spinlocks 2010-04-07 16:15:05 -07:00
rwsem.c rwsem: smaller wrappers around rwsem_down_failed_common 2010-08-09 20:45:11 -07:00
scatterlist.c scatterlist: prevent invalid free when alloc fails 2010-08-30 19:55:09 +02:00
sha1.c
show_mem.c mm: use the same log level for show_mem() 2010-03-06 11:26:27 -08:00
smp_processor_id.c
sort.c
spinlock_debug.c locking: Further name space cleanups 2009-12-14 23:55:33 +01:00
string_helpers.c
string.c lib/string.c: simplify strnstr() 2010-03-06 11:26:35 -08:00
swiotlb.c swiotlb: Use page alignment for early buffer allocation 2010-10-11 17:08:36 -04:00
syscall.c
textsearch.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
ts_bm.c
ts_fsm.c
ts_kmp.c
uuid.c Unified UUID/GUID definition 2010-05-19 22:40:47 -04:00
vsprintf.c lib: fix scnprintf() if @size is == 0 2010-10-26 16:52:16 -07:00