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[patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when cpusets are disabled

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  [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when cpusets  are disabled David Rientjes <rientjes@google.com> - 2017-01-18 23:00 +0100
    Re: [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when  cpusets are disabled Vlastimil Babka <vbabka@suse.cz> - 2017-01-19 08:40 +0100
      Re: [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when  cpusets are disabled Michal Hocko <mhocko@kernel.org> - 2017-01-19 10:00 +0100
      [patch] mm, oom: header nodemask is NULL when cpusets are disabled David Rientjes <rientjes@google.com> - 2017-01-20 00:00 +0100
        Re: [patch] mm, oom: header nodemask is NULL when cpusets are disabled "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-01-20 08:20 +0100
          [patch -mm] mm, oom: header nodemask is NULL when cpusets are disabled  fix David Rientjes <rientjes@google.com> - 2017-01-20 11:10 +0100
        Re: [patch] mm, oom: header nodemask is NULL when cpusets are  disabled Vlastimil Babka <vbabka@suse.cz> - 2017-01-20 10:20 +0100
          Re: [patch] mm, oom: header nodemask is NULL when cpusets are  disabled David Rientjes <rientjes@google.com> - 2017-01-20 11:10 +0100
        Re: [patch] mm, oom: header nodemask is NULL when cpusets are  disabled Michal Hocko <mhocko@kernel.org> - 2017-01-24 11:20 +0100

#1562207 — [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when cpusets are disabled

The patch "mm, page_alloc: warn_alloc print nodemask" implicitly sets the 
allocation nodemask to cpuset_current_mems_allowed when there is no 
effective mempolicy.  cpuset_current_mems_allowed is only effective when 
cpusets are enabled, which is also printed by warn_alloc(), so setting 
the nodemask to cpuset_current_mems_allowed is redundant and prevents 
debugging issues where ac->nodemask is not set properly in the page 
allocator.

This provides better debugging output since 
cpuset_print_current_mems_allowed() is already provided.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 mm/page_alloc.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3037,7 +3037,6 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
 	va_list args;
 	static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL,
 				      DEFAULT_RATELIMIT_BURST);
-	nodemask_t *nm = (nodemask) ? nodemask : &cpuset_current_mems_allowed;
 
 	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) ||
 	    debug_guardpage_minorder() > 0)
@@ -3051,11 +3050,16 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
 	pr_cont("%pV", &vaf);
 	va_end(args);
 
-	pr_cont(", mode:%#x(%pGg), nodemask=%*pbl\n", gfp_mask, &gfp_mask, nodemask_pr_args(nm));
+	pr_cont(", mode:%#x(%pGg), nodemask=", gfp_mask, &gfp_mask);
+	if (nodemask)
+		pr_cont("%*pbl\n", nodemask_pr_args(nodemask));
+	else
+		pr_cont("(null)\n");
+
 	cpuset_print_current_mems_allowed();
 
 	dump_stack();
-	warn_alloc_show_mem(gfp_mask, nm);
+	warn_alloc_show_mem(gfp_mask, nodemask);
 }
 
 static inline struct page *

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#1562442 — Re: [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when cpusets are disabled

On 01/18/2017 10:51 PM, David Rientjes wrote:
> The patch "mm, page_alloc: warn_alloc print nodemask" implicitly sets the 
> allocation nodemask to cpuset_current_mems_allowed when there is no 
> effective mempolicy.  cpuset_current_mems_allowed is only effective when 
> cpusets are enabled, which is also printed by warn_alloc(), so setting 
> the nodemask to cpuset_current_mems_allowed is redundant and prevents 
> debugging issues where ac->nodemask is not set properly in the page 
> allocator.
> 
> This provides better debugging output since 
> cpuset_print_current_mems_allowed() is already provided.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>

Yes, with my current cpuset vs mempolicy debugging experience, this is
more useful (except how both nodemask and mems_allowed can change under
us, so what we print here is not necessarily the same that what
get_page_from_freelist() has seen, but that's another thing...).

But I would suggest you change the oom killer's dump_header() the same
way than warn_alloc().

Thanks,
Vlastimil

> ---
>  mm/page_alloc.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3037,7 +3037,6 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
>  	va_list args;
>  	static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL,
>  				      DEFAULT_RATELIMIT_BURST);
> -	nodemask_t *nm = (nodemask) ? nodemask : &cpuset_current_mems_allowed;
>  
>  	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) ||
>  	    debug_guardpage_minorder() > 0)
> @@ -3051,11 +3050,16 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
>  	pr_cont("%pV", &vaf);
>  	va_end(args);
>  
> -	pr_cont(", mode:%#x(%pGg), nodemask=%*pbl\n", gfp_mask, &gfp_mask, nodemask_pr_args(nm));
> +	pr_cont(", mode:%#x(%pGg), nodemask=", gfp_mask, &gfp_mask);
> +	if (nodemask)
> +		pr_cont("%*pbl\n", nodemask_pr_args(nodemask));
> +	else
> +		pr_cont("(null)\n");
> +
>  	cpuset_print_current_mems_allowed();
>  
>  	dump_stack();
> -	warn_alloc_show_mem(gfp_mask, nm);
> +	warn_alloc_show_mem(gfp_mask, nodemask);
>  }
>  
>  static inline struct page *
> 

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#1562481 — Re: [patch -mm] mm, page_alloc: warn_alloc nodemask is NULL when cpusets are disabled

On Thu 19-01-17 08:29:45, Vlastimil Babka wrote:
> On 01/18/2017 10:51 PM, David Rientjes wrote:
> > The patch "mm, page_alloc: warn_alloc print nodemask" implicitly sets the 
> > allocation nodemask to cpuset_current_mems_allowed when there is no 
> > effective mempolicy.  cpuset_current_mems_allowed is only effective when 
> > cpusets are enabled, which is also printed by warn_alloc(), so setting 
> > the nodemask to cpuset_current_mems_allowed is redundant and prevents 
> > debugging issues where ac->nodemask is not set properly in the page 
> > allocator.
> > 
> > This provides better debugging output since 
> > cpuset_print_current_mems_allowed() is already provided.
> > 
> > Signed-off-by: David Rientjes <rientjes@google.com>
> 
> Yes, with my current cpuset vs mempolicy debugging experience, this is
> more useful (except how both nodemask and mems_allowed can change under
> us, so what we print here is not necessarily the same that what
> get_page_from_freelist() has seen, but that's another thing...).
> 
> But I would suggest you change the oom killer's dump_header() the same
> way than warn_alloc().

Yes please

-- 
Michal Hocko
SUSE Labs

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#1563178 — [patch] mm, oom: header nodemask is NULL when cpusets are disabled

Commit 82e7d3abec86 ("oom: print nodemask in the oom report") implicitly 
sets the allocation nodemask to cpuset_current_mems_allowed when there is 
no effective mempolicy.  cpuset_current_mems_allowed is only effective 
when cpusets are enabled, which is also printed by dump_header(), so 
setting the nodemask to cpuset_current_mems_allowed is redundant and 
prevents debugging issues where ac->nodemask is not set properly in the 
page allocator.

This provides better debugging output since 
cpuset_print_current_mems_allowed() is already provided.

Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: David Rientjes <rientjes@google.com>
---
 mm/oom_kill.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -403,12 +403,14 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
 
 static void dump_header(struct oom_control *oc, struct task_struct *p)
 {
-	nodemask_t *nm = (oc->nodemask) ? oc->nodemask : &cpuset_current_mems_allowed;
-
-	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n",
-		current->comm, oc->gfp_mask, &oc->gfp_mask,
-		nodemask_pr_args(nm), oc->order,
-		current->signal->oom_score_adj);
+	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=",
+		current->comm, oc->gfp_mask, &oc->gfp_mask);
+	if (oc->nodemask)
+		pr_cont("%*pbl", nodemask_pr_args(oc->nodemask));
+	else
+		pr_cont("(null)\n");
+	pr_cont(",  order=%d, oom_score_adj=%hd\n",
+		oc->order, current->signal->oom_score_adj);
 	if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
 		pr_warn("COMPACTION is disabled!!!\n");
 
@@ -417,7 +419,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
 	if (oc->memcg)
 		mem_cgroup_print_oom_info(oc->memcg, p);
 	else
-		show_mem(SHOW_MEM_FILTER_NODES, nm);
+		show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask);
 	if (sysctl_oom_dump_tasks)
 		dump_tasks(oc->memcg, oc->nodemask);
 }

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#1563338 — Re: [patch] mm, oom: header nodemask is NULL when cpusets are disabled

On Friday, January 20, 2017 6:58 AM David Rientjes wrote: 
> 
> Commit 82e7d3abec86 ("oom: print nodemask in the oom report") implicitly
> sets the allocation nodemask to cpuset_current_mems_allowed when there is
> no effective mempolicy.  cpuset_current_mems_allowed is only effective
> when cpusets are enabled, which is also printed by dump_header(), so
> setting the nodemask to cpuset_current_mems_allowed is redundant and
> prevents debugging issues where ac->nodemask is not set properly in the
> page allocator.
> 
> This provides better debugging output since
> cpuset_print_current_mems_allowed() is already provided.
> 
> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

>  mm/oom_kill.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -403,12 +403,14 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
> 
>  static void dump_header(struct oom_control *oc, struct task_struct *p)
>  {
> -	nodemask_t *nm = (oc->nodemask) ? oc->nodemask : &cpuset_current_mems_allowed;
> -
> -	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n",
> -		current->comm, oc->gfp_mask, &oc->gfp_mask,
> -		nodemask_pr_args(nm), oc->order,
> -		current->signal->oom_score_adj);
> +	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=",
> +		current->comm, oc->gfp_mask, &oc->gfp_mask);
> +	if (oc->nodemask)
> +		pr_cont("%*pbl", nodemask_pr_args(oc->nodemask));
> +	else
> +		pr_cont("(null)\n");

Nit: no newline needed.

> +	pr_cont(",  order=%d, oom_score_adj=%hd\n",
> +		oc->order, current->signal->oom_score_adj);
>  	if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
>  		pr_warn("COMPACTION is disabled!!!\n");
> 
> @@ -417,7 +419,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
>  	if (oc->memcg)
>  		mem_cgroup_print_oom_info(oc->memcg, p);
>  	else
> -		show_mem(SHOW_MEM_FILTER_NODES, nm);
> +		show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask);
>  	if (sysctl_oom_dump_tasks)
>  		dump_tasks(oc->memcg, oc->nodemask);
>  }
> 

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#1563438 — [patch -mm] mm, oom: header nodemask is NULL when cpusets are disabled fix

Newline per Hillf

Signed-off-by: David Rientjes <rientjes@google.com>
---
 mm/oom_kill.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1767e50844ac..51c091849dcb 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -408,7 +408,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
 	if (oc->nodemask)
 		pr_cont("%*pbl", nodemask_pr_args(oc->nodemask));
 	else
-		pr_cont("(null)\n");
+		pr_cont("(null)");
 	pr_cont(",  order=%d, oom_score_adj=%hd\n",
 		oc->order, current->signal->oom_score_adj);
 	if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)

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#1563404 — Re: [patch] mm, oom: header nodemask is NULL when cpusets are disabled

On 01/19/2017 11:57 PM, David Rientjes wrote:
> Commit 82e7d3abec86 ("oom: print nodemask in the oom report") implicitly 
> sets the allocation nodemask to cpuset_current_mems_allowed when there is 
> no effective mempolicy.  cpuset_current_mems_allowed is only effective 
> when cpusets are enabled, which is also printed by dump_header(), so 
> setting the nodemask to cpuset_current_mems_allowed is redundant and 
> prevents debugging issues where ac->nodemask is not set properly in the 
> page allocator.
> 
> This provides better debugging output since 
> cpuset_print_current_mems_allowed() is already provided.
> 
> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  mm/oom_kill.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -403,12 +403,14 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
>  
>  static void dump_header(struct oom_control *oc, struct task_struct *p)
>  {
> -	nodemask_t *nm = (oc->nodemask) ? oc->nodemask : &cpuset_current_mems_allowed;
> -
> -	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n",
> -		current->comm, oc->gfp_mask, &oc->gfp_mask,
> -		nodemask_pr_args(nm), oc->order,
> -		current->signal->oom_score_adj);
> +	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=",
> +		current->comm, oc->gfp_mask, &oc->gfp_mask);
> +	if (oc->nodemask)
> +		pr_cont("%*pbl", nodemask_pr_args(oc->nodemask));
> +	else
> +		pr_cont("(null)\n");
> +	pr_cont(",  order=%d, oom_score_adj=%hd\n",
> +		oc->order, current->signal->oom_score_adj);
>  	if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
>  		pr_warn("COMPACTION is disabled!!!\n");
>  
> @@ -417,7 +419,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
>  	if (oc->memcg)
>  		mem_cgroup_print_oom_info(oc->memcg, p);
>  	else
> -		show_mem(SHOW_MEM_FILTER_NODES, nm);
> +		show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask);
>  	if (sysctl_oom_dump_tasks)
>  		dump_tasks(oc->memcg, oc->nodemask);
>  }
> 

Could we simplify both patches with something like this?
Although the sizeof("null") is not the nicest thing, because it relies on knowledge
that pointer() in lib/vsprintf.c uses this string. Maybe Rasmus has some better idea?

Thanks,
Vlastimil

diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index f746e44d4046..4add88ef63f0 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -103,7 +103,7 @@ extern nodemask_t _unused_nodemask_arg_;
  *
  * Can be used to provide arguments for '%*pb[l]' when printing a nodemask.
  */
-#define nodemask_pr_args(maskp)		MAX_NUMNODES, (maskp)->bits
+#define nodemask_pr_args(maskp)		((maskp) ? MAX_NUMNODES : (int) sizeof("null")), ((maskp) ? (maskp)->bits : NULL)
 
 /*
  * The inline keyword gives the compiler room to decide to inline, or

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#1563432 — Re: [patch] mm, oom: header nodemask is NULL when cpusets are disabled

On Fri, 20 Jan 2017, Vlastimil Babka wrote:

> Could we simplify both patches with something like this?
> Although the sizeof("null") is not the nicest thing, because it relies on knowledge
> that pointer() in lib/vsprintf.c uses this string. Maybe Rasmus has some better idea?
> 
> Thanks,
> Vlastimil
> 
> diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
> index f746e44d4046..4add88ef63f0 100644
> --- a/include/linux/nodemask.h
> +++ b/include/linux/nodemask.h
> @@ -103,7 +103,7 @@ extern nodemask_t _unused_nodemask_arg_;
>   *
>   * Can be used to provide arguments for '%*pb[l]' when printing a nodemask.
>   */
> -#define nodemask_pr_args(maskp)		MAX_NUMNODES, (maskp)->bits
> +#define nodemask_pr_args(maskp)		((maskp) ? MAX_NUMNODES : (int) sizeof("null")), ((maskp) ? (maskp)->bits : NULL)
>  
>  /*
>   * The inline keyword gives the compiler room to decide to inline, or
> 

That's creative.  I'm not sure if it's worth it considering 
nodemask_pr_args() is usually used in a context where we know we have a 
nodemask :)  These would be the only two exceptions.

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#1565755 — Re: [patch] mm, oom: header nodemask is NULL when cpusets are disabled

On Thu 19-01-17 14:57:36, David Rientjes wrote:
> Commit 82e7d3abec86 ("oom: print nodemask in the oom report") implicitly 
> sets the allocation nodemask to cpuset_current_mems_allowed when there is 
> no effective mempolicy.  cpuset_current_mems_allowed is only effective 
> when cpusets are enabled, which is also printed by dump_header(), so 
> setting the nodemask to cpuset_current_mems_allowed is redundant and 
> prevents debugging issues where ac->nodemask is not set properly in the 
> page allocator.
> 
> This provides better debugging output since 
> cpuset_print_current_mems_allowed() is already provided.
> 
> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: David Rientjes <rientjes@google.com>

With the removed \n addressed in the follow up fix
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/oom_kill.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -403,12 +403,14 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
>  
>  static void dump_header(struct oom_control *oc, struct task_struct *p)
>  {
> -	nodemask_t *nm = (oc->nodemask) ? oc->nodemask : &cpuset_current_mems_allowed;
> -
> -	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n",
> -		current->comm, oc->gfp_mask, &oc->gfp_mask,
> -		nodemask_pr_args(nm), oc->order,
> -		current->signal->oom_score_adj);
> +	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=",
> +		current->comm, oc->gfp_mask, &oc->gfp_mask);
> +	if (oc->nodemask)
> +		pr_cont("%*pbl", nodemask_pr_args(oc->nodemask));
> +	else
> +		pr_cont("(null)\n");
> +	pr_cont(",  order=%d, oom_score_adj=%hd\n",
> +		oc->order, current->signal->oom_score_adj);
>  	if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
>  		pr_warn("COMPACTION is disabled!!!\n");
>  
> @@ -417,7 +419,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
>  	if (oc->memcg)
>  		mem_cgroup_print_oom_info(oc->memcg, p);
>  	else
> -		show_mem(SHOW_MEM_FILTER_NODES, nm);
> +		show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask);
>  	if (sysctl_oom_dump_tasks)
>  		dump_tasks(oc->memcg, oc->nodemask);
>  }

-- 
Michal Hocko
SUSE Labs

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