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Thomas Richter 0dd1979f7f perf test: Fix test case Merge cpu map 
Commit a2408a7036 ("perf evlist: Maintain evlist->all_cpus")
introduces a test case for cpumap merge operation, see functions
perf_cpu_map__merge() and test__cpu_map_merge().

The test case fails on s390 with this error message:

 [root@m35lp76 perf]# ./perf test -Fvvvvv 52
 52: Merge cpu map                                         :
 --- start ---
 cpumask list: 1-2,4-5,7
 perf: /root/linux/tools/include/linux/refcount.h:131:\
          refcount_sub_and_test: Assertion `!(new > val)' failed.
 Aborted (core dumped)
 [root@m35lp76 perf]#

The root cause is in the function test__cpu_map_merge():
It creates two cpu_maps named 'a' and 'b':

  struct perf_cpu_map *a = perf_cpu_map__new("4,2,1");
  struct perf_cpu_map *b = perf_cpu_map__new("4,5,7");

and creates a third map named 'c' which is the result of
the merge of maps a and b:

  struct perf_cpu_map *c = perf_cpu_map__merge(a, b);

After some verifaction of the merged cpu_map all three
of them are have their reference count reduced and are
freed:

   perf_cpu_map__put(a); (1)
   perf_cpu_map__put(b);
   perf_cpu_map__put(c);

The release of perf_cpu_map__put(a) is wrong. The map
is already released and free'ed as part of the function

  perf_cpu_map__merge(struct perf_cpu_map *orig,
  |	              struct perf_cpu_map *other)
  +--> perf_cpu_map__put(orig);
       |
       +--> cpu_map__delete(orig)

At the end perf_cpu_map_put() is called for map 'orig'
alias 'a' and since the reference count is 1, the map
is deleted, as can be seen by the following gdb trace:

 (gdb) where
 #0  tcache_put (tc_idx=0, chunk=0x156cc30) at malloc.c:2940
 #1  _int_free (av=0x3fffd49ee80 <main_arena>, p=0x156cc30,
		     have_lock=<optimized out>) at malloc.c:4222
 #2  0x00000000012d5e78 in cpu_map__delete (map=0x156cc40) at cpumap.c:31
 #3  0x00000000012d5f7a in perf_cpu_map__put (map=0x156cc40) at cpumap.c:45
 #4  0x00000000012d723a in perf_cpu_map__merge (orig=0x156cc40,
     other=0x156cc60) at cpumap.c:343
 #5  0x000000000110cdd0 in test__cpu_map_merge (
     test=0x14ea6c8 <generic_tests+2856>, subtest=-1) at tests/cpumap.c:128

Thus the perf_cpu_map__put(a) (see (1) above) frees map 'a'
a second time and causes the failure. Fix this be removing that
function call.

Output after:
  [root@m35lp76 perf]# ./perf test -Fvvvvv 52
  52: Merge cpu map                                         :
  --- start ---
  cpumask list: 1-2,4-5,7
  ---- end ----
  Merge cpu map: Ok
  [root@m35lp76 perf]#

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: sumanthk@linux.ibm.com
Link: http://lore.kernel.org/lkml/20200120132011.64698-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-01-30 11:55:02 +01:00
arch Linux 5.5-rc7 2020-01-20 08:43:44 +01:00
block block: fix an integer overflow in logical block size 2020-01-15 21:43:09 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
drivers Linux 5.5-rc7 2020-01-20 08:43:44 +01:00
fs Linux 5.5-rc7 2020-01-20 08:43:44 +01:00
include Linux 5.5-rc7 2020-01-20 08:43:44 +01:00
init mm, debug_pagealloc: don't rely on static keys too early 2020-01-13 18:19:02 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel Merge branch 'core/kprobes' into perf/core, to pick up fixes 2020-01-28 07:59:05 +01:00
lib lib/vdso: Make __cvdso_clock_getres() static 2020-01-10 19:29:01 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid 2020-01-13 18:19:02 -08:00
net Linux 5.5-rc7 2020-01-20 08:43:44 +01:00
samples samples/seccomp: Zero out members based on seccomp_notif_sizes 2020-01-02 13:03:39 -08:00
scripts Kbuild fixes for v5.5 (2nd) 2020-01-03 11:21:25 -08:00
security + Bug fixes 2020-01-04 19:28:30 -08:00
sound sound fixes for 5.5-rc7 2020-01-17 08:38:35 -08:00
tools perf test: Fix test case Merge cpu map 2020-01-30 11:55:02 +01:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap MAINTAINERS: update my email address 2020-01-11 14:33:39 -08:00
COPYING
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
Makefile Linux 5.5-rc7 2020-01-19 16:02:49 -08:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.