Nick Piggin 8301e7e348 radix-tree: fix RCU bug ... commit 27d20fddc8 upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>		2010-12-09 13:32:53 -08:00
..
acpi	ACPI: Fix typos	2010-09-28 21:38:19 -04:00
asm-generic	gpio: doc updates	2010-09-09 18:57:24 -07:00
crypto
drm	drm/ttm: Fix two race conditions + fix busy codepaths	2010-10-06 09:04:43 +10:00
keys	DNS: Separate out CIFS DNS Resolver code	2010-08-05 17:17:51 +00:00
linux	radix-tree: fix RCU bug	2010-12-09 13:32:53 -08:00
math-emu
media	V4L/DVB: videobuf-dma-sg: set correct size in last sg element	2010-09-27 22:22:01 -03:00
mtd	mtd: Update copyright notices	2010-08-08 20:58:20 +01:00
net	mac80211: clear txflags for ps-filtered frames	2010-12-09 13:32:12 -08:00
pcmcia	pcmcia: use struct resource for PCMCIA devices, part 2	2010-08-03 09:04:16 +02:00
rdma	IB: Rename RAW_ETY to RAW_ETHERTYPE	2010-08-04 10:44:19 -07:00
rxrpc
scsi	scsi: use __uX types for headers exported to user space	2010-08-11 08:59:01 -07:00
sound	ALSA: emu10k1 - delay the PCM interrupts (add pcm_irq_delay parameter)	2010-08-18 15:10:59 +02:00
trace	Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2010-08-24 12:21:49 -07:00
video	include: replace unifdef-y with header-y	2010-08-14 22:26:51 +02:00
xen	xen: pvhvm: make it clearer that XEN_UNPLUG_* define bits in a bitfield	2010-08-23 12:01:35 +01:00
Kbuild