Jens Axboe 60b0ea120c percpu_counter: fix bad counter state during suspend ... I got a bug report yesterday from Laszlo Ersek <lersek@xxxxxxxxxx>, in which he states that his kvm instance fails to suspend. He Laszlo bisected it down to this commit: commit 1cf7e9c68f Author: Jens Axboe <axboe@xxxxxxxxx> Date: Fri Nov 1 10:52:52 2013 -0600 virtio_blk: blk-mq support where virtio-blk is converted to use the blk-mq infrastructure. After digging a bit, it became clear that the issue was with the queue drain. blk-mq tracks queue usage in a percpu counter, which is incremented on request alloc and decremented when the request is freed. The initial hunt was for an inconsistency in blk-mq, but everything seemed fine. In fact, the counter only returned crazy values when suspend was in progress. When a CPU is unplugged, the percpu counters merges that CPU state with the general state. blk-mq takes care to register a hotcpu notifier with the appropriate priority, so we know it runs after the percpu counter notifier. However, the percpu counter notifier only merges the state when the CPU is fully gone. This leaves a state transition where the CPU going away is no longer in the online mask, yet it still holds private values. This means that in this state, percpu_counter_sum() returns invalid results, and the suspend then hangs waiting for abs(dead-cpu-value) requests to complete which of course will never happen. Fix this by clearing the state earlier, so we never have a case where the CPU isn't in online mask but still holds private state. This bug has been there since forever, I guess we don't have a lot of users where percpu counters needs to be reliable during the suspend cycle. Reported-by: <lersek@redhat.com> Tested-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>		2014-04-07 08:17:10 -06:00
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fonts	partly revert commit 8a10bc9: parisc/sti_console: prefer Linux fonts over built-in ROM fonts	2014-03-23 16:44:42 +01:00
lz4	lz4: fix compression/decompression signedness mismatch	2013-09-11 15:59:45 -07:00
lzo	…
mpi	MPILIB: add module description and license	2013-09-25 17:17:01 +01:00
raid6	…
reed_solomon	…
xz	…
zlib_deflate	…
zlib_inflate	…
.gitignore	…
Kconfig	Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2013-11-21 19:46:00 -08:00
Kconfig.debug	locktorture: Add a lock-torture kernel module	2014-02-23 09:04:29 -08:00
Kconfig.kgdb	…
Kconfig.kmemcheck	…
Makefile	* Avoid WARN_ON() when mapping BGRT on Baytrail (EFI 32-bit).	2014-02-07 11:27:30 -08:00
argv_split.c	…
asn1_decoder.c	…
assoc_array.c	assoc_array: remove global variable	2014-01-23 09:25:10 -08:00
atomic64.c	…
atomic64_test.c	…
audit.c	…
average.c	lib: Ensure EWMA does not store wrong intermediate values	2014-01-16 23:46:06 -08:00
bcd.c	…
bch.c	…
bitmap.c	…
bitrev.c	…
bsearch.c	…
btree.c	…
bug.c	…
build_OID_registry	…
bust_spinlocks.c	…
check_signature.c	…
checksum.c	…
clz_ctz.c	lib/clz_ctz.c: add prototype declarations in lib/clz_ctz.c	2014-04-03 16:21:12 -07:00
clz_tab.c	…
cmdline.c	lib/cmdline.c: declare exported symbols immediately	2014-01-23 16:36:57 -08:00
cordic.c	…
cpu-notifier-error-inject.c	…
cpu_rmap.c	Remove GENERIC_HARDIRQ config option	2013-09-13 15:09:52 +02:00
cpumask.c	lib/cpumask.c: use memblock apis for early memory allocations	2014-01-21 16:19:47 -08:00
crc-ccitt.c	…
crc-itu-t.c	…
crc-t10dif.c	crypto: crct10dif - Add fallback for broken initrds	2013-09-12 15:31:34 +10:00
crc7.c	…
crc8.c	…
crc16.c	…
crc32.c	lib: crc32: reduce number of cases for crc32{, c}_combine	2013-11-04 15:27:08 -05:00
crc32defs.h	…
ctype.c	…
debug_locks.c	…
debugobjects.c	lib/debugobjects.c: remove unnecessary work pending test	2013-11-13 12:09:22 +09:00
dec_and_lock.c	…
decompress.c	…
decompress_bunzip2.c	…
decompress_inflate.c	lib/decompress_inflate.c: include appropriate header file	2014-04-03 16:21:12 -07:00
decompress_unlz4.c	lib/decompress_unlz4.c: always set an error return code on failures	2014-01-23 16:37:04 -08:00
decompress_unlzma.c	…
decompress_unlzo.c	…
decompress_unxz.c	…
devres.c	lib/devres.c: fix some sparse warnings	2014-04-03 16:21:11 -07:00
digsig.c	lib/digsig.c: use ERR_CAST inlined function instead of ERR_PTR(PTR_ERR(...))	2013-11-13 12:09:22 +09:00
div64.c	…
dma-debug.c	dma debug: account for cachelines and read-only mappings in overlap tracking	2014-03-04 07:55:47 -08:00
dump_stack.c	…
dynamic_debug.c	dynamic_debug: replace obselete simple_strtoul() with kstrtouint()	2014-01-27 21:02:39 -08:00
dynamic_queue_limits.c	…
earlycpio.c	…
extable.c	…
fault-inject.c	…
fdt.c	…
fdt_ro.c	…
fdt_rw.c	…
fdt_strerror.c	…
fdt_sw.c	…
fdt_wip.c	…
find_last_bit.c	…
find_next_bit.c	…
flex_array.c	reciprocal_divide: update/correction of the algorithm	2014-01-21 23:17:20 -08:00
flex_proportions.c	…
gcd.c	…
gen_crc32table.c	…
genalloc.c	lib/genalloc.c: add check gen_pool_dma_alloc() if dma pointer is not NULL	2014-01-29 16:22:39 -08:00
halfmd4.c	…
hash.c	lib: hash: follow-up fixups for arch hash	2013-12-19 00:14:53 -05:00
hexdump.c	lib: introduce upper case hex ascii helpers	2013-09-20 15:38:26 -04:00
hweight.c	…
idr.c	idr: Add new function idr_is_empty()	2014-02-17 16:27:47 +01:00
inflate.c	…
int_sqrt.c	…
interval_tree.c	…
interval_tree_test_main.c	…
iomap.c	…
iomap_copy.c	…
iommu-helper.c	…
ioremap.c	…
iovec.c	…
irq_regs.c	…
is_single_threaded.c	…
jedec_ddr_data.c	…
kasprintf.c	…
kfifo.c	kfifo: kfifo_copy_{to,from}_user: fix copied bytes calculation	2013-11-15 09:32:23 +09:00
klist.c	…
kobject.c	sysfs, kobject: add sysfs wrapper for kernfs_enable_ns()	2014-02-07 16:08:57 -08:00
kobject_uevent.c	kobject: don't block for each kobject_uevent	2014-04-03 16:21:04 -07:00
kstrtox.c	lib/kstrtox.c: remove redundant cleanup	2014-01-23 16:36:57 -08:00
kstrtox.h	…
lcm.c	…
libcrc32c.c	…
list_debug.c	…
list_sort.c	…
llist.c	llists-move-llist_reverse_order-from-raid5-to-llistc-fix	2013-11-15 09:32:22 +09:00
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	sched: Introduce preempt_count accessor functions	2013-09-25 14:07:32 +02:00
lockref.c	lockref: include mutex.h rather than reinvent arch_mutex_cpu_relax	2013-11-27 20:37:33 -08:00
lru_cache.c	…
md5.c	…
memory-notifier-error-inject.c	…
memweight.c	…
net_utils.c	…
nlattr.c	netlink: don't compare the nul-termination in nla_strcmp	2014-04-01 15:25:02 -04:00
notifier-error-inject.c	…
notifier-error-inject.h	…
of-reconfig-notifier-error-inject.c	…
oid_registry.c	…
parser.c	lib/parser.c: put EXPORT_SYMBOLs in the conventional place	2014-01-23 16:36:55 -08:00
pci_iomap.c	…
percpu-refcount.c	percpu-refcount: Add a WARN() for ref going negative	2014-01-21 04:40:56 -05:00
percpu_counter.c	percpu_counter: fix bad counter state during suspend	2014-04-07 08:17:10 -06:00
percpu_ida.c	Merge branch 'for-linus' of git://git.kernel.dk/linux-block	2014-02-14 10:45:18 -08:00
percpu_test.c	percpu: add test module for various percpu operations	2013-11-13 12:09:11 +09:00
plist.c	…
pm-notifier-error-inject.c	…
prio_heap.c	…
proportions.c	…
radix-tree.c	mm: keep page cache radix tree nodes in check	2014-04-03 16:21:01 -07:00
random32.c	lib/random32.c: minor cleanups and kdoc fix	2014-04-03 16:21:11 -07:00
ratelimit.c	…
rational.c	…
rbtree.c	rbtree: add postorder iteration functions	2013-09-11 15:59:19 -07:00
rbtree_test.c	rbtree/test: test rbtree_postorder_for_each_entry_safe()	2014-01-23 16:37:03 -08:00
reciprocal_div.c	reciprocal_divide: update/correction of the algorithm	2014-01-21 23:17:20 -08:00
scatterlist.c	lib/scatterlist: export sg_miter_skip()	2013-12-08 17:56:37 -08:00
sha1.c	…
show_mem.c	lib/show_mem.c: show num_poisoned_pages when oom	2014-01-21 16:19:48 -08:00
smp_processor_id.c	sched: Introduce preempt_count accessor functions	2013-09-25 14:07:32 +02:00
sort.c	…
stmp_device.c	…
string.c	asmlinkage Make __stack_chk_failed and memcmp visible	2014-02-13 18:13:43 -08:00
string_helpers.c	…
strncpy_from_user.c	…
strnlen_user.c	…
swiotlb.c	memblock, nobootmem: add memblock_virt_alloc_low()	2014-01-27 21:02:38 -08:00
syscall.c	lib/syscall.c: unexport task_current_syscall()	2014-04-03 16:21:06 -07:00
test-kstrtox.c	…
test-string_helpers.c	…
test_module.c	test: add minimal module for verification testing	2014-01-23 16:36:57 -08:00
test_user_copy.c	test: check copy_to/from_user boundary validation	2014-01-23 16:36:57 -08:00
textsearch.c	…
timerqueue.c	…
ts_bm.c	…
ts_fsm.c	…
ts_kmp.c	…
ucs2_string.c	…
usercopy.c	…
uuid.c	…
vsprintf.c	vsprintf: remove %n handling	2014-04-03 16:21:07 -07:00