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Eric Dumazet d7ce369243 dump_stack: avoid potential deadlocks 
Some servers experienced fatal deadlocks because of a combination of
bugs, leading to multiple cpus calling dump_stack().

The checksumming bug was fixed in commit 34ae6a1aa0 ("ipv6: update
skb->csum when CE mark is propagated").

The second problem is a faulty locking in dump_stack()

CPU1 runs in process context and calls dump_stack(), grabs dump_lock.

   CPU2 receives a TCP packet under softirq, grabs socket spinlock, and
   call dump_stack() from netdev_rx_csum_fault().

   dump_stack() spins on atomic_cmpxchg(&dump_lock, -1, 2), since
   dump_lock is owned by CPU1

While dumping its stack, CPU1 is interrupted by a softirq, and happens
to process a packet for the TCP socket locked by CPU2.

CPU1 spins forever in spin_lock() : deadlock

Stack trace on CPU1 looked like :

    NMI backtrace for cpu 1
    RIP: _raw_spin_lock+0x25/0x30
    ...
    Call Trace:
      <IRQ>
      tcp_v6_rcv+0x243/0x620
      ip6_input_finish+0x11f/0x330
      ip6_input+0x38/0x40
      ip6_rcv_finish+0x3c/0x90
      ipv6_rcv+0x2a9/0x500
      process_backlog+0x461/0xaa0
      net_rx_action+0x147/0x430
      __do_softirq+0x167/0x2d0
      call_softirq+0x1c/0x30
      do_softirq+0x3f/0x80
      irq_exit+0x6e/0xc0
      smp_call_function_single_interrupt+0x35/0x40
      call_function_single_interrupt+0x6a/0x70
      <EOI>
      printk+0x4d/0x4f
      printk_address+0x31/0x33
      print_trace_address+0x33/0x3c
      print_context_stack+0x7f/0x119
      dump_trace+0x26b/0x28e
      show_trace_log_lvl+0x4f/0x5c
      show_stack_log_lvl+0x104/0x113
      show_stack+0x42/0x44
      dump_stack+0x46/0x58
      netdev_rx_csum_fault+0x38/0x3c
      __skb_checksum_complete_head+0x6e/0x80
      __skb_checksum_complete+0x11/0x20
      tcp_rcv_established+0x2bd5/0x2fd0
      tcp_v6_do_rcv+0x13c/0x620
      sk_backlog_rcv+0x15/0x30
      release_sock+0xd2/0x150
      tcp_recvmsg+0x1c1/0xfc0
      inet_recvmsg+0x7d/0x90
      sock_recvmsg+0xaf/0xe0
      ___sys_recvmsg+0x111/0x3b0
      SyS_recvmsg+0x5c/0xb0
      system_call_fastpath+0x16/0x1b

Fixes: b58d977432 ("dump_stack: serialize the output from dump_stack()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-05 18:10:40 -08:00
..
842 crypto: 842 - remove WARN inside printk 2015-12-23 18:20:01 +08:00
fonts
lz4 lz4: fix system halt at boot kernel on x86_64 2015-05-24 11:56:29 -07:00
lzo
mpi lib/mpi: only require buffers as big as needed for the integer 2015-11-17 22:00:39 +08:00
raid6 powerpc: Create disable_kernel_{fp,altivec,vsx,spe}() 2015-12-01 13:52:25 +11:00
reed_solomon
xz
zlib_deflate zlib_deflate/deftree: remove bi_reverse() 2015-09-10 13:29:01 -07:00
zlib_inflate
.gitignore
argv_split.c
asn1_decoder.c ASN.1: Handle 'ANY OPTIONAL' in grammar 2015-08-05 13:38:07 +01:00
assoc_array.c
atomic64_test.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-11 14:39:17 -08:00
atomic64.c atomic: Provide atomic_{or,xor,and} 2015-07-27 14:06:24 +02:00
audit.c
bcd.c
bch.c
bitmap.c lib/bitmap.c: bitmap_parselist can accept string with whitespaces on head or tail 2015-09-10 13:29:01 -07:00
bitrev.c
bsearch.c
btree.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
bug.c module: Sanitize RCU usage and locking 2015-05-28 11:31:52 +09:30
build_OID_registry
bust_spinlocks.c
check_signature.c
checksum.c
clz_ctz.c
clz_tab.c
cmdline.c
compat_audit.c
cordic.c
cpu_rmap.c sched/topology: Rename topology_thread_cpumask() to topology_sibling_cpumask() 2015-05-27 15:22:15 +02:00
cpu-notifier-error-inject.c
cpumask.c revert "cpumask: don't perform while loop in cpumask_next_and()" 2015-06-18 17:00:23 -10:00
crc7.c
crc8.c
crc16.c
crc32.c
crc32defs.h
crc-ccitt.c
crc-itu-t.c lib: crc-itu-t.[ch] fix 0x0x prefix in integer constants 2015-05-26 15:26:43 +02:00
crc-t10dif.c lib: introduce crc_t10dif_update() 2015-05-30 22:42:24 -07:00
ctype.c
debug_info.c kbuild: include core debug info when DEBUG_INFO_REDUCED 2015-06-11 15:08:32 +02:00
debug_locks.c
debugobjects.c debugobjects: Allow bigger number of early boot objects 2016-01-27 15:40:59 +01:00
dec_and_lock.c
decompress_bunzip2.c lib/decompressors: use real out buf size for gunzip with kernel 2015-09-10 13:29:01 -07:00
decompress_inflate.c lib/decompressors: use real out buf size for gunzip with kernel 2015-09-10 13:29:01 -07:00
decompress_unlz4.c lib/decompressors: use real out buf size for gunzip with kernel 2015-09-10 13:29:01 -07:00
decompress_unlzma.c lib/decompress_unlzma: Do a NULL check for pointer 2015-09-10 13:29:01 -07:00
decompress_unlzo.c lib/decompressors: use real out buf size for gunzip with kernel 2015-09-10 13:29:01 -07:00
decompress_unxz.c lib/decompressors: use real out buf size for gunzip with kernel 2015-09-10 13:29:01 -07:00
decompress.c lib/decompress: set the compressor name to NULL on error 2015-07-17 16:39:54 -07:00
devres.c devres: fix a for loop bounds check 2015-10-05 04:49:54 +01:00
digsig.c KEYS: Merge the type-specific data with the payload data 2015-10-21 15:18:36 +01:00
div64.c __div64_32(): make it overridable at compile time 2015-11-16 14:42:12 -05:00
dma-debug.c dma-debug: switch check from _text to _stext 2016-01-14 16:00:49 -08:00
dump_stack.c dump_stack: avoid potential deadlocks 2016-02-05 18:10:40 -08:00
dynamic_debug.c convert a bunch of open-coded instances of memdup_user_nul() 2016-01-04 10:26:58 -05:00
dynamic_queue_limits.c
earlycpio.c
extable.c
fault-inject.c fault-inject: fix inverted interval/probability values in printk 2015-10-23 17:55:10 +09:00
fdt_empty_tree.c
fdt_ro.c
fdt_rw.c
fdt_strerror.c
fdt_sw.c
fdt_wip.c
fdt.c
find_bit.c lib: rename lib/find_next_bit.c to lib/find_bit.c 2015-04-17 09:03:54 -04:00
flex_array.c
flex_proportions.c
gcd.c
gen_crc32table.c
genalloc.c CPM/QE: use genalloc to manage CPM/QE muram 2015-12-22 17:10:18 -06:00
glob.c
halfmd4.c lib/halfmd4.c: use rol32 inline function in the ROUND macro 2015-11-06 17:50:42 -08:00
hexdump.c lib/hexdump.c: truncate output in case of overflow 2015-11-06 17:50:42 -08:00
hweight.c
idr.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
inflate.c
int_sqrt.c
interval_tree_test.c
interval_tree.c
iomap_copy.c lib/iomap_copy.c: add __ioread32_copy() 2016-01-20 17:09:18 -08:00
iomap.c
iommu-common.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2015-11-05 16:34:48 -08:00
iommu-helper.c
ioremap.c
iov_iter.c iov_iter: export import_single_range() 2015-12-06 20:42:19 -05:00
irq_poll.c irq_poll: Fix irq_poll_sched() 2016-01-19 15:26:55 -05:00
irq_regs.c
is_single_threaded.c lib/is_single_threaded.c: change current_is_single_threaded() to use for_each_thread() 2015-11-06 17:50:42 -08:00
jedec_ddr_data.c
kasprintf.c lib/kasprintf.c: add sanity check to kvasprintf 2016-01-16 11:17:27 -08:00
Kconfig Initial roundup of 4.5 merge window patches 2016-01-23 18:45:06 -08:00
Kconfig.debug Merge branch 'akpm' (patches from Andrew) 2016-01-21 12:32:08 -08:00
Kconfig.kasan mm, slub, kasan: enable user tracking by default with KASAN=y 2015-11-05 19:34:48 -08:00
Kconfig.kgdb
Kconfig.kmemcheck
Kconfig.ubsan UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
kfifo.c
klist.c klist: implement klist_prev() 2015-07-28 08:50:42 +01:00
kobject_uevent.c
kobject.c lib/kobject.c: use kvasprintf_const for formatting ->name 2015-11-06 17:50:42 -08:00
kstrtox.c kstrto*: accept "-0" for signed conversion 2015-09-10 13:29:01 -07:00
kstrtox.h
lcm.c
libcrc32c.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-01-22 11:58:43 -08:00
list_debug.c mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup 2016-01-15 17:56:32 -08:00
list_sort.c lib/list_sort: use late_initcall to hook in self tests 2015-06-16 14:12:35 -04:00
llist.c lib/llist.c: fix data race in llist_del_first 2015-11-06 17:50:42 -08:00
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
lockref.c locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition 2015-08-12 11:59:04 +02:00
lru_cache.c lru_cache: Converted lc_seq_printf_status to return void 2015-11-25 09:22:02 -07:00
Makefile Initial roundup of 4.5 merge window patches 2016-01-23 18:45:06 -08:00
md5.c
memory-notifier-error-inject.c
memweight.c
net_utils.c
netdev-notifier-error-inject.c net: Add support for CHANGEUPPER notifier error injection 2015-12-03 11:49:23 -05:00
nlattr.c
nmi_backtrace.c ARM: 8439/1: Fix backtrace generation when IPI is masked 2015-10-03 16:40:51 +01:00
notifier-error-inject.c
notifier-error-inject.h
of-reconfig-notifier-error-inject.c
oid_registry.c
once.c once: make helper generic for calling functions once 2015-10-08 05:26:36 -07:00
parser.c
pci_iomap.c libnvdimm for 4.3: 2015-09-08 14:35:59 -07:00
percpu_counter.c percpu_counter: batch size aware __percpu_counter_compare() 2015-05-29 07:39:34 +10:00
percpu_ida.c mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 2015-11-06 17:50:42 -08:00
percpu_test.c
percpu-refcount.c
plist.c
pm-notifier-error-inject.c
proportions.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
radix-tree.c radix-tree: fix race in gang lookup 2016-02-03 08:28:43 -08:00
random32.c random32: add prandom_init_once helper for own rngs 2015-10-08 05:26:38 -07:00
ratelimit.c ratelimit: fix bug in time interval by resetting right begin time 2016-01-21 17:20:51 -08:00
rational.c
rbtree_test.c
rbtree.c rbtree: Make lockless searches non-fatal 2015-05-28 11:32:04 +09:30
reciprocal_div.c
rhashtable.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-12-31 18:20:10 -05:00
scatterlist.c scatterlist: allow limited chaining without ARCH_HAS_SG_CHAIN 2015-08-17 08:12:51 -06:00
seq_buf.c tracing: Use seq_buf_used() in seq_buf_to_user() instead of len 2015-12-23 14:27:20 -05:00
sg_split.c lib: scatterlist: add sg splitting function 2015-08-24 14:28:01 -06:00
sha1.c
show_mem.c lib/show_mem.c: correct reserved memory calculation 2015-09-08 15:35:28 -07:00
smp_processor_id.c
sort.c lib/sort: Add 64 bit swap function 2015-06-25 17:00:40 -07:00
stmp_device.c
string_helpers.c string_helpers: fix precision loss for some inputs 2016-01-20 17:09:18 -08:00
string.c lib/string.c: add ULL suffix to the constant definition 2015-11-10 16:32:11 -08:00
strncpy_from_user.c Use the new batched user accesses in generic user string handling 2015-12-17 10:05:19 -08:00
strnlen_user.c Use the new batched user accesses in generic user string handling 2015-12-17 10:05:19 -08:00
swiotlb.c Merge branch 'for-4.2/sg' of git://git.kernel.dk/linux-block 2015-06-25 15:22:36 -07:00
syscall.c
test_bpf.c bpf, test: add couple of test cases 2015-12-18 16:04:51 -05:00
test_firmware.c test: firmware_class: add asynchronous request trigger 2016-01-07 13:44:22 -07:00
test_hexdump.c test_hexdump: print statistics at the end 2016-01-20 17:09:18 -08:00
test_kasan.c lib: test_kasan: add some testcases 2015-11-05 19:34:48 -08:00
test_module.c
test_printf.c lib/test_printf.c: test dentry printing 2016-01-16 11:17:29 -08:00
test_rhashtable.c rhashtable-test: allow to retry even if -ENOMEM was returned 2015-11-23 12:36:08 -05:00
test_static_key_base.c locking/static_keys: Provide a selftest 2015-08-03 11:51:12 +02:00
test_static_keys.c locking/static_keys: Make verify_keys() static 2015-08-05 09:53:40 +02:00
test_user_copy.c
test-kstrtox.c kstrto*: accept "-0" for signed conversion 2015-09-10 13:29:01 -07:00
test-string_helpers.c lib/test-string_helpers.c: fix and improve string_get_size() tests 2016-02-03 08:28:43 -08:00
textsearch.c
timerqueue.c timerqueue: Let timerqueue_add/del return information 2015-04-22 17:06:49 +02:00
ts_bm.c
ts_fsm.c
ts_kmp.c
ubsan.c UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
ubsan.h UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
ucs2_string.c
usercopy.c
uuid.c
vsprintf.c lib/vsprintf: factor out %pN[F] handler as netdev_bits() 2016-01-16 11:17:30 -08:00