diff mbox series

[v5,3/5] writeback: fix build problems of "writeback: support retrieving per group debug writeback stats of bdi"

Message ID 20240423034643.141219-4-shikemeng@huaweicloud.com (mailing list archive)
State New
Headers show
Series Improve visibility of writeback | expand

Commit Message

Kemeng Shi April 23, 2024, 3:46 a.m. UTC 
Fix two build problems:
1. implicit declaration of function 'cgroup_ino'.
2. unused variable 'stats'.

After this fix, No build problem is found when CGROUPS is disabled.
The wb_stats could be successfully retrieved when CGROUP_WRITEBACK is
disabled:
cat wb_stats
WbCgIno:                    1
WbWriteback:                0 kB
WbReclaimable:         685440 kB
WbDirtyThresh:      195530960 kB
WbDirtied:             691488 kB
WbWritten:               6048 kB
WbWriteBandwidth:      102400 kBps
b_dirty:                    2
b_io:                       0
b_more_io:                  0
b_dirty_time:               0
state:                      5

cat wb_stats
WbCgIno:                    1
WbWriteback:                0 kB
WbReclaimable:         818944 kB
WbDirtyThresh:      195527484 kB
WbDirtied:             824992 kB
WbWritten:               6048 kB
WbWriteBandwidth:      102400 kBps
b_dirty:                    2
b_io:                       0
b_more_io:                  0
b_dirty_time:               0
state:                      5

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
---
 mm/backing-dev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Kemeng Shi April 23, 2024, 3:53 a.m. UTC | #1 
on 4/23/2024 11:46 AM, Kemeng Shi wrote:
> Fix two build problems:
> 1. implicit declaration of function 'cgroup_ino'.
> 2. unused variable 'stats'.
> 
> After this fix, No build problem is found when CGROUPS is disabled.
> The wb_stats could be successfully retrieved when CGROUP_WRITEBACK is
> disabled:
> cat wb_stats
> WbCgIno:                    1
> WbWriteback:                0 kB
> WbReclaimable:         685440 kB
> WbDirtyThresh:      195530960 kB
> WbDirtied:             691488 kB
> WbWritten:               6048 kB
> WbWriteBandwidth:      102400 kBps
> b_dirty:                    2
> b_io:                       0
> b_more_io:                  0
> b_dirty_time:               0
> state:                      5
> 
> cat wb_stats
> WbCgIno:                    1
> WbWriteback:                0 kB
> WbReclaimable:         818944 kB
> WbDirtyThresh:      195527484 kB
> WbDirtied:             824992 kB
> WbWritten:               6048 kB
> WbWriteBandwidth:      102400 kBps
> b_dirty:                    2
> b_io:                       0
> b_more_io:                  0
> b_dirty_time:               0
> state:                      5
> 
> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reported-by: SeongJae Park <sj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Sorry for missing reported-by tags.

> ---
>  mm/backing-dev.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 6ecd11bdce6e..e61bbb1bd622 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -172,7 +172,11 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb,
>  		   "b_more_io:         %10lu\n"
>  		   "b_dirty_time:      %10lu\n"
>  		   "state:             %10lx\n\n",
> +#ifdef CONFIG_CGROUP_WRITEBACK
>  		   cgroup_ino(wb->memcg_css->cgroup),
> +#else
> +		   1ul,
> +#endif
>  		   K(stats->nr_writeback),
>  		   K(stats->nr_reclaimable),
>  		   K(stats->wb_thresh),
> @@ -192,7 +196,6 @@ static int cgwb_debug_stats_show(struct seq_file *m, void *v)
>  	unsigned long background_thresh;
>  	unsigned long dirty_thresh;
>  	struct bdi_writeback *wb;
> -	struct wb_stats stats;
>  
>  	global_dirty_limits(&background_thresh, &dirty_thresh);
>  
>
Johannes Weiner April 24, 2024, 1:27 p.m. UTC | #2 
Hi Kemeng,

On Tue, Apr 23, 2024 at 11:46:41AM +0800, Kemeng Shi wrote:
> Fix two build problems:
> 1. implicit declaration of function 'cgroup_ino'.

I just ran into this as well, with defconfig on mm-everything:

/home/hannes/src/linux/linux/mm/backing-dev.c: In function 'wb_stats_show':
/home/hannes/src/linux/linux/mm/backing-dev.c:175:33: error: 'struct bdi_writeback' has no member named 'memcg_css'
  175 |                    cgroup_ino(wb->memcg_css->cgroup),
      |                                 ^~
make[3]: *** [/home/hannes/src/linux/linux/scripts/Makefile.build:244: mm/backing-dev.o] Error 1

> ---
>  mm/backing-dev.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 6ecd11bdce6e..e61bbb1bd622 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -172,7 +172,11 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb,
>  		   "b_more_io:         %10lu\n"
>  		   "b_dirty_time:      %10lu\n"
>  		   "state:             %10lx\n\n",
> +#ifdef CONFIG_CGROUP_WRITEBACK
>  		   cgroup_ino(wb->memcg_css->cgroup),
> +#else
> +		   1ul,
> +#endif
>  		   K(stats->nr_writeback),
>  		   K(stats->nr_reclaimable),
>  		   K(stats->wb_thresh),
> @@ -192,7 +196,6 @@ static int cgwb_debug_stats_show(struct seq_file *m, void *v)
>  	unsigned long background_thresh;
>  	unsigned long dirty_thresh;
>  	struct bdi_writeback *wb;
> -	struct wb_stats stats;
>  
>  	global_dirty_limits(&background_thresh, &dirty_thresh);

The fix looks right to me, but it needs to be folded into the previous
patch. No patch should knowingly introduce an issue that is fixed
later on. This will break bisection.
Kemeng Shi April 25, 2024, 1:22 a.m. UTC | #3 
Hi Johannes,
on 4/24/2024 9:27 PM, Johannes Weiner wrote:
> Hi Kemeng,
> 
> On Tue, Apr 23, 2024 at 11:46:41AM +0800, Kemeng Shi wrote:
>> Fix two build problems:
>> 1. implicit declaration of function 'cgroup_ino'.
> 
> I just ran into this as well, with defconfig on mm-everything:
Sorry for this.
> 
> /home/hannes/src/linux/linux/mm/backing-dev.c: In function 'wb_stats_show':
> /home/hannes/src/linux/linux/mm/backing-dev.c:175:33: error: 'struct bdi_writeback' has no member named 'memcg_css'
>   175 |                    cgroup_ino(wb->memcg_css->cgroup),
>       |                                 ^~
> make[3]: *** [/home/hannes/src/linux/linux/scripts/Makefile.build:244: mm/backing-dev.o] Error 1
> 
>> ---
>>  mm/backing-dev.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
>> index 6ecd11bdce6e..e61bbb1bd622 100644
>> --- a/mm/backing-dev.c
>> +++ b/mm/backing-dev.c
>> @@ -172,7 +172,11 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb,
>>  		   "b_more_io:         %10lu\n"
>>  		   "b_dirty_time:      %10lu\n"
>>  		   "state:             %10lx\n\n",
>> +#ifdef CONFIG_CGROUP_WRITEBACK
>>  		   cgroup_ino(wb->memcg_css->cgroup),
>> +#else
>> +		   1ul,
>> +#endif
>>  		   K(stats->nr_writeback),
>>  		   K(stats->nr_reclaimable),
>>  		   K(stats->wb_thresh),
>> @@ -192,7 +196,6 @@ static int cgwb_debug_stats_show(struct seq_file *m, void *v)
>>  	unsigned long background_thresh;
>>  	unsigned long dirty_thresh;
>>  	struct bdi_writeback *wb;
>> -	struct wb_stats stats;
>>  
>>  	global_dirty_limits(&background_thresh, &dirty_thresh);
> 
> The fix looks right to me, but it needs to be folded into the previous
> patch. No patch should knowingly introduce an issue that is fixed
> later on. This will break bisection.
As I'm not sure if previous patch is already applied to tree, so I
make this fix a individual patch and mentioned in cover letter that
this could be folded if previous patch is not in tree or this could
be applied individually to fix the introduced issue. As Androw told
me that little fixups would be preferred instead of entire resend in
current stage, I guess a new series with this patch foled should not
be necessary. If a new series is still needed, please let me konw.
I would like to it.

Thanks.
diff mbox series

Patch

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 6ecd11bdce6e..e61bbb1bd622 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -172,7 +172,11 @@  static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb,
 		   "b_more_io:         %10lu\n"
 		   "b_dirty_time:      %10lu\n"
 		   "state:             %10lx\n\n",
+#ifdef CONFIG_CGROUP_WRITEBACK
 		   cgroup_ino(wb->memcg_css->cgroup),
+#else
+		   1ul,
+#endif
 		   K(stats->nr_writeback),
 		   K(stats->nr_reclaimable),
 		   K(stats->wb_thresh),
@@ -192,7 +196,6 @@  static int cgwb_debug_stats_show(struct seq_file *m, void *v)
 	unsigned long background_thresh;
 	unsigned long dirty_thresh;
 	struct bdi_writeback *wb;
-	struct wb_stats stats;
 
 	global_dirty_limits(&background_thresh, &dirty_thresh);