[peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 5620 bytes --]

CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: Yafang Shao <laoar.shao@gmail.com>
CC: Peter Zijlstra <peterz@infradead.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
head:   2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d
commit: 445d9e8ba05d5e9e4b26956b7fe529223e29d8d1 [13/19] sched: make struct sched_statistics independent of fair sched class
:::::: branch date: 10 hours ago
:::::: commit date: 10 hours ago
config: x86_64-randconfig-m001-20210910 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

vim +/se +453 kernel/sched/debug.c

3866e845ed5222 kernel/sched/debug.c Steven Rostedt (Red Hat  2016-02-22  439) 
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  440  #ifdef CONFIG_FAIR_GROUP_SCHED
5091faa449ee0b kernel/sched_debug.c Mike Galbraith           2010-11-30  441  static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  442  {
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  443  	struct sched_entity *se = tg->se[cpu];
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05 @444  	struct sched_statistics *stats = __schedstats_from_se(se);
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  445  
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  446  #define P(F)		SEQ_printf(m, "  .%-30s: %lld\n",	#F, (long long)F)
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  447  #define P_SCHEDSTAT(F)	SEQ_printf(m, "  .%-30s: %lld\n",	\
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  448  		#F, (long long)schedstat_val(stats->F))
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  449  #define PN(F)		SEQ_printf(m, "  .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  450  #define PN_SCHEDSTAT(F)	SEQ_printf(m, "  .%-30s: %lld.%06ld\n", \
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  451  		#F, SPLIT_NS((long long)schedstat_val(stats->F)))
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  452  
cd126afe838d7e kernel/sched/debug.c Yuyang Du                2015-07-15 @453  	if (!se)
18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  454  		return;
18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  455  
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  456  	PN(se->exec_start);
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  457  	PN(se->vruntime);
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  458  	PN(se->sum_exec_runtime);
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  459  
cb2517653fccaf kernel/sched/debug.c Mel Gorman               2016-02-05  460  	if (schedstat_enabled()) {
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  461  		PN_SCHEDSTAT(wait_start);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  462  		PN_SCHEDSTAT(sleep_start);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  463  		PN_SCHEDSTAT(block_start);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  464  		PN_SCHEDSTAT(sleep_max);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  465  		PN_SCHEDSTAT(block_max);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  466  		PN_SCHEDSTAT(exec_max);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  467  		PN_SCHEDSTAT(slice_max);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  468  		PN_SCHEDSTAT(wait_max);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  469  		PN_SCHEDSTAT(wait_sum);
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  470  		P_SCHEDSTAT(wait_count);
cb2517653fccaf kernel/sched/debug.c Mel Gorman               2016-02-05  471  	}
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  472  
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  473  	P(se->load.weight);
9d85f21c94f7f7 kernel/sched/debug.c Paul Turner              2012-10-04  474  #ifdef CONFIG_SMP
9d89c257dfb9c5 kernel/sched/debug.c Yuyang Du                2015-07-15  475  	P(se->avg.load_avg);
9d89c257dfb9c5 kernel/sched/debug.c Yuyang Du                2015-07-15  476  	P(se->avg.util_avg);
9f68395333ad7f kernel/sched/debug.c Vincent Guittot          2020-02-24  477  	P(se->avg.runnable_avg);
9d85f21c94f7f7 kernel/sched/debug.c Paul Turner              2012-10-04  478  #endif
4fa8d299b43a91 kernel/sched/debug.c Josh Poimboeuf           2016-06-17  479  

:::::: The code at line 453 was first introduced by commit
:::::: cd126afe838d7ea9b971cdea087fd498a7293c7f sched/fair: Remove rq's runnable avg

:::::: TO: Yuyang Du <yuyang.du@intel.com>
:::::: CC: Ingo Molnar <mingo@kernel.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

[-- Attachment #2: config.gz --]
[-- Type: application/gzip, Size: 29328 bytes --]

[peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[Dan Carpenter]

[-- Attachment #1: Type: text/plain, Size: 3275 bytes --]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
head:   2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d
commit: 445d9e8ba05d5e9e4b26956b7fe529223e29d8d1 [13/19] sched: make struct sched_statistics independent of fair sched class
config: x86_64-randconfig-m001-20210910 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

vim +/se +453 kernel/sched/debug.c

3866e845ed5222 kernel/sched/debug.c Steven Rostedt (Red Hat  2016-02-22  439) 
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  440  #ifdef CONFIG_FAIR_GROUP_SCHED
5091faa449ee0b kernel/sched_debug.c Mike Galbraith           2010-11-30  441  static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  442  {
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  443  	struct sched_entity *se = tg->se[cpu];
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05 @444  	struct sched_statistics *stats = __schedstats_from_se(se);
                                                                                                                                      ^^
New unchecked dereference.

ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  445  
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  446  #define P(F)		SEQ_printf(m, "  .%-30s: %lld\n",	#F, (long long)F)
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  447  #define P_SCHEDSTAT(F)	SEQ_printf(m, "  .%-30s: %lld\n",	\
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  448  		#F, (long long)schedstat_val(stats->F))
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  449  #define PN(F)		SEQ_printf(m, "  .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  450  #define PN_SCHEDSTAT(F)	SEQ_printf(m, "  .%-30s: %lld.%06ld\n", \
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  451  		#F, SPLIT_NS((long long)schedstat_val(stats->F)))
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  452  
cd126afe838d7e kernel/sched/debug.c Yuyang Du                2015-07-15 @453  	if (!se)
                                                                                    ^^^
The old code assumed "se" can be NULL.

18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  454  		return;
18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  455  
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  456  	PN(se->exec_start);
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  457  	PN(se->vruntime);

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

[peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
head:   2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d
commit: 445d9e8ba05d5e9e4b26956b7fe529223e29d8d1 [13/19] sched: make struct sched_statistics independent of fair sched class
config: x86_64-randconfig-m001-20210910 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

vim +/se +453 kernel/sched/debug.c

3866e845ed5222 kernel/sched/debug.c Steven Rostedt (Red Hat  2016-02-22  439) 
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  440  #ifdef CONFIG_FAIR_GROUP_SCHED
5091faa449ee0b kernel/sched_debug.c Mike Galbraith           2010-11-30  441  static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  442  {
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  443  	struct sched_entity *se = tg->se[cpu];
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05 @444  	struct sched_statistics *stats = __schedstats_from_se(se);
                                                                                                                                      ^^
New unchecked dereference.

ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  445  
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  446  #define P(F)		SEQ_printf(m, "  .%-30s: %lld\n",	#F, (long long)F)
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  447  #define P_SCHEDSTAT(F)	SEQ_printf(m, "  .%-30s: %lld\n",	\
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  448  		#F, (long long)schedstat_val(stats->F))
97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  449  #define PN(F)		SEQ_printf(m, "  .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  450  #define PN_SCHEDSTAT(F)	SEQ_printf(m, "  .%-30s: %lld.%06ld\n", \
445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  451  		#F, SPLIT_NS((long long)schedstat_val(stats->F)))
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  452  
cd126afe838d7e kernel/sched/debug.c Yuyang Du                2015-07-15 @453  	if (!se)
                                                                                    ^^^
The old code assumed "se" can be NULL.

18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  454  		return;
18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  455  
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  456  	PN(se->exec_start);
ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  457  	PN(se->vruntime);

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Re: [peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[Yafang Shao]

On Mon, Sep 13, 2021 at 4:48 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
> head:   2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d
> commit: 445d9e8ba05d5e9e4b26956b7fe529223e29d8d1 [13/19] sched: make struct sched_statistics independent of fair sched class
> config: x86_64-randconfig-m001-20210910 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> smatch warnings:
> kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)
>

Sorry, my bad.

Hi Peter,

Could you pls. help amend below change to the original commit ?

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 52b4426414c0..d59f33ac06fe 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -440,11 +440,8 @@ void dirty_sched_domain_sysctl(int cpu)
 #ifdef CONFIG_FAIR_GROUP_SCHED
 static void print_cfs_group_stats(struct seq_file *m, int cpu, struct
task_group *tg)
 {
-       struct sched_statistics __maybe_unused *stats;
        struct sched_entity *se = tg->se[cpu];

-       stats = __schedstats_from_se(se);
-
 #define P(F)           SEQ_printf(m, "  .%-30s: %lld\n",       #F,
(long long)F)
 #define P_SCHEDSTAT(F) SEQ_printf(m, "  .%-30s: %lld\n",       \
                #F, (long long)schedstat_val(stats->F))
@@ -460,6 +457,8 @@ static void print_cfs_group_stats(struct seq_file
*m, int cpu, struct task_group
        PN(se->sum_exec_runtime);

        if (schedstat_enabled()) {
+               struct sched_statistics *stats =  __schedstats_from_se(se);
+
                PN_SCHEDSTAT(wait_start);
                PN_SCHEDSTAT(sleep_start);
                PN_SCHEDSTAT(block_start);



> vim +/se +453 kernel/sched/debug.c
>
> 3866e845ed5222 kernel/sched/debug.c Steven Rostedt (Red Hat  2016-02-22  439)
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  440  #ifdef CONFIG_FAIR_GROUP_SCHED
> 5091faa449ee0b kernel/sched_debug.c Mike Galbraith           2010-11-30  441  static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  442  {
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  443    struct sched_entity *se = tg->se[cpu];
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05 @444    struct sched_statistics *stats = __schedstats_from_se(se);
>                                                                                                                                       ^^
> New unchecked dereference.
>
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  445
> 97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  446  #define P(F)              SEQ_printf(m, "  .%-30s: %lld\n",       #F, (long long)F)
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  447  #define P_SCHEDSTAT(F)    SEQ_printf(m, "  .%-30s: %lld\n",       \
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  448            #F, (long long)schedstat_val(stats->F))
> 97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  449  #define PN(F)             SEQ_printf(m, "  .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  450  #define PN_SCHEDSTAT(F)   SEQ_printf(m, "  .%-30s: %lld.%06ld\n", \
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  451            #F, SPLIT_NS((long long)schedstat_val(stats->F)))
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  452
> cd126afe838d7e kernel/sched/debug.c Yuyang Du                2015-07-15 @453    if (!se)
>                                                                                     ^^^
> The old code assumed "se" can be NULL.
>
> 18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  454            return;
> 18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  455
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  456    PN(se->exec_start);
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  457    PN(se->vruntime);
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>


--
Thanks
Yafang

Re: [peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[Yafang Shao]

[-- Attachment #1: Type: text/plain, Size: 4723 bytes --]

On Mon, Sep 13, 2021 at 4:48 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
> head:   2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d
> commit: 445d9e8ba05d5e9e4b26956b7fe529223e29d8d1 [13/19] sched: make struct sched_statistics independent of fair sched class
> config: x86_64-randconfig-m001-20210910 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> smatch warnings:
> kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)
>

Sorry, my bad.

Hi Peter,

Could you pls. help amend below change to the original commit ?

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 52b4426414c0..d59f33ac06fe 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -440,11 +440,8 @@ void dirty_sched_domain_sysctl(int cpu)
 #ifdef CONFIG_FAIR_GROUP_SCHED
 static void print_cfs_group_stats(struct seq_file *m, int cpu, struct
task_group *tg)
 {
-       struct sched_statistics __maybe_unused *stats;
        struct sched_entity *se = tg->se[cpu];

-       stats = __schedstats_from_se(se);
-
 #define P(F)           SEQ_printf(m, "  .%-30s: %lld\n",       #F,
(long long)F)
 #define P_SCHEDSTAT(F) SEQ_printf(m, "  .%-30s: %lld\n",       \
                #F, (long long)schedstat_val(stats->F))
@@ -460,6 +457,8 @@ static void print_cfs_group_stats(struct seq_file
*m, int cpu, struct task_group
        PN(se->sum_exec_runtime);

        if (schedstat_enabled()) {
+               struct sched_statistics *stats =  __schedstats_from_se(se);
+
                PN_SCHEDSTAT(wait_start);
                PN_SCHEDSTAT(sleep_start);
                PN_SCHEDSTAT(block_start);



> vim +/se +453 kernel/sched/debug.c
>
> 3866e845ed5222 kernel/sched/debug.c Steven Rostedt (Red Hat  2016-02-22  439)
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  440  #ifdef CONFIG_FAIR_GROUP_SCHED
> 5091faa449ee0b kernel/sched_debug.c Mike Galbraith           2010-11-30  441  static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  442  {
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  443    struct sched_entity *se = tg->se[cpu];
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05 @444    struct sched_statistics *stats = __schedstats_from_se(se);
>                                                                                                                                       ^^
> New unchecked dereference.
>
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  445
> 97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  446  #define P(F)              SEQ_printf(m, "  .%-30s: %lld\n",       #F, (long long)F)
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  447  #define P_SCHEDSTAT(F)    SEQ_printf(m, "  .%-30s: %lld\n",       \
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  448            #F, (long long)schedstat_val(stats->F))
> 97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar              2018-03-03  449  #define PN(F)             SEQ_printf(m, "  .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  450  #define PN_SCHEDSTAT(F)   SEQ_printf(m, "  .%-30s: %lld.%06ld\n", \
> 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao              2021-09-05  451            #F, SPLIT_NS((long long)schedstat_val(stats->F)))
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  452
> cd126afe838d7e kernel/sched/debug.c Yuyang Du                2015-07-15 @453    if (!se)
>                                                                                     ^^^
> The old code assumed "se" can be NULL.
>
> 18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  454            return;
> 18bf2805d9b30c kernel/sched/debug.c Ben Segall               2012-10-04  455
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  456    PN(se->exec_start);
> ff9b48c3598732 kernel/sched_debug.c Bharata B Rao            2008-11-10  457    PN(se->vruntime);
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
>


--
Thanks
Yafang

Re: [peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[Peter Zijlstra]

On Mon, Sep 13, 2021 at 07:04:14PM +0800, Yafang Shao wrote:
> Hi Peter,
> 
> Could you pls. help amend below change to the original commit ?

Yep, will do, thanks!

Re: [peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444)

[Peter Zijlstra]

[-- Attachment #1: Type: text/plain, Size: 169 bytes --]

On Mon, Sep 13, 2021 at 07:04:14PM +0800, Yafang Shao wrote:
> Hi Peter,
> 
> Could you pls. help amend below change to the original commit ?

Yep, will do, thanks!