Date:   Tue, 10 Jul 2018 14:03:12 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     ufo19890607@...il.com
Cc:     akpm@...ux-foundation.org, rientjes@...gle.com,
        kirill.shutemov@...ux.intel.com, aarcange@...hat.com,
        penguin-kernel@...ove.sakura.ne.jp, guro@...com,
        yang.s@...baba-inc.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, yuzhoujian@...ichuxing.com
Subject: Re: [PATCH v13 1/2] Reorganize the oom report in dump_header

On Tue 10-07-18 18:19:47, ufo19890607@...il.com wrote:
> From: yuzhoujian <yuzhoujian@...ichuxing.com>
> 
> OOM report contains several sections. The first one is the allocation
> context that has triggered the OOM. Then we have cpuset context
> followed by the stack trace of the OOM path. Followed by the oom
> eligible tasks and the information about the chosen oom victim.
> 
> One thing that makes parsing more awkward than necessary is that we do
> not have a single and easily parsable line about the oom context. This
> patch is reorganizing the oom report to
> 1) who invoked oom and what was the allocation request
>         [  126.168182] panic invoked oom-killer: gfp_mask=0x6280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), order=0, oom_score_adj=0
> 
> 2) OOM stack trace
>         [  126.169806] CPU: 23 PID: 8668 Comm: panic Not tainted 4.18.0-rc4+ #44
>         [  126.170494] Hardware name: Inspur SA5212M4/YZMB-00370-107, BIOS 4.1.10 11/14/2016
>         [  126.171197] Call Trace:
>         [  126.171901]  dump_stack+0x5a/0x73
>         [  126.172593]  dump_header+0x58/0x2dc
>         [  126.173294]  oom_kill_process+0x228/0x420
>         [  126.173999]  ? oom_badness+0x2a/0x130
>         [  126.174705]  out_of_memory+0x11a/0x4a0
>         [  126.175415]  __alloc_pages_slowpath+0x7cc/0xa1e
>         [  126.176128]  ? __alloc_pages_slowpath+0x194/0xa1e
>         [  126.176853]  ? page_counter_try_charge+0x54/0xc0
>         [  126.177580]  __alloc_pages_nodemask+0x277/0x290
>         [  126.178319]  alloc_pages_vma+0x73/0x180
>         [  126.179058]  do_anonymous_page+0xed/0x5a0
>         [  126.179825]  __handle_mm_fault+0xbb3/0xe70
>         [  126.180566]  handle_mm_fault+0xfa/0x210
>         [  126.181313]  __do_page_fault+0x233/0x4c0
>         [  126.182063]  do_page_fault+0x32/0x140
>         [  126.182812]  ? page_fault+0x8/0x30
>         [  126.183560]  page_fault+0x1e/0x30
> 
> 3) oom context (contrains and the chosen victim).
>         [  126.190619] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0-1,task=panic,pid=10235,uid=    0
> 
> An admin can easily get the full oom context at a single line which
> makes parsing much easier.
> 
> Signed-off-by: yuzhoujian <yuzhoujian@...ichuxing.com>

OK, this looks better
Acked-by: Michal Hocko <mhocko@...e.com>

> ---
> Changes since v12:
> - print the cpuset and memory allocation information after oom victim comm, pid.
> 
> Changes since v11:
> - move the array of const char oom_constraint_text to oom_kill.c
> - add the cpuset information in the one line output.
> 
> Changes since v10:
> - divide the patch v8 into two parts. One part is to add the array of const char and put enum
>   oom_constaint into oom.h; the other adds a new func to print the missing information for the system-
>   wide oom report.
> 
> Changes since v9:
> - divide the patch v8 into two parts. One part is to move enum oom_constraint into memcontrol.h; the
>   other refactors the output info in the dump_header.
> - replace orgin_memcg and kill_memcg with oom_memcg and task_memcg resptively.
> 
> Changes since v8:
> - add the constraint in the oom_control structure.
> - put enum oom_constraint and constraint array into the oom.h file.
> - simplify the description for mem_cgroup_print_oom_context.
> 
> Changes since v7:
> - add the constraint parameter to dump_header and oom_kill_process.
> - remove the static char array in the mem_cgroup_print_oom_context, and
>   invoke pr_cont_cgroup_path to print memcg' name.
> - combine the patchset v6 into one.
> 
> Changes since v6:
> - divide the patch v5 into two parts. One part is to add an array of const char and
>   put enum oom_constraint into the memcontrol.h; the other refactors the output
>   in the dump_header.
> - limit the memory usage for the static char array by using NAME_MAX in the mem_cgroup_print_oom_context.
> - eliminate the spurious spaces in the oom's output and fix the spelling of "constrain".
> 
> Changes since v5:
> - add an array of const char for each constraint.
> - replace all of the pr_cont with a single line print of the pr_info.
> - put enum oom_constraint into the memcontrol.c file for printing oom constraint.
> 
> Changes since v4:
> - rename the helper's name to mem_cgroup_print_oom_context.
> - rename the mem_cgroup_print_oom_info to mem_cgroup_print_oom_meminfo.
> - add the constrain info in the dump_header.
> 
> Changes since v3:
> - rename the helper's name to mem_cgroup_print_oom_memcg_name.
> - add the rcu lock held to the helper.
> - remove the print info of memcg's name in mem_cgroup_print_oom_info.
> 
> Changes since v2:
> - add the mem_cgroup_print_memcg_name helper to print the memcg's
>   name which contains the task that will be killed by the oom-killer.
> 
> Changes since v1:
> - replace adding mem_cgroup_print_oom_info with printing the memcg's
>   name only.
> 
>  include/linux/oom.h    | 10 ++++++++++
>  kernel/cgroup/cpuset.c |  4 ++--
>  mm/oom_kill.c          | 37 +++++++++++++++++++++----------------
>  mm/page_alloc.c        |  4 ++--
>  4 files changed, 35 insertions(+), 20 deletions(-)
> 
> diff --git a/include/linux/oom.h b/include/linux/oom.h
> index 6adac113e96d..3e5e01619bc8 100644
> --- a/include/linux/oom.h
> +++ b/include/linux/oom.h
> @@ -15,6 +15,13 @@ struct notifier_block;
>  struct mem_cgroup;
>  struct task_struct;
>  
> +enum oom_constraint {
> +	CONSTRAINT_NONE,
> +	CONSTRAINT_CPUSET,
> +	CONSTRAINT_MEMORY_POLICY,
> +	CONSTRAINT_MEMCG,
> +};
> +
>  /*
>   * Details of the page allocation that triggered the oom killer that are used to
>   * determine what should be killed.
> @@ -42,6 +49,9 @@ struct oom_control {
>  	unsigned long totalpages;
>  	struct task_struct *chosen;
>  	unsigned long chosen_points;
> +
> +	/* Used to print the constraint info. */
> +	enum oom_constraint constraint;
>  };
>  
>  extern struct mutex oom_lock;
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 266f10cb7222..9510a5b32eaf 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -2666,9 +2666,9 @@ void cpuset_print_current_mems_allowed(void)
>  	rcu_read_lock();
>  
>  	cgrp = task_cs(current)->css.cgroup;
> -	pr_info("%s cpuset=", current->comm);
> +	pr_cont(",cpuset=");
>  	pr_cont_cgroup_name(cgrp);
> -	pr_cont(" mems_allowed=%*pbl\n",
> +	pr_cont(",mems_allowed=%*pbl",
>  		nodemask_pr_args(&current->mems_allowed));
>  
>  	rcu_read_unlock();
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 84081e77bc51..531b2c86d4db 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -237,11 +237,11 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
>  	return points > 0 ? points : 1;
>  }
>  
> -enum oom_constraint {
> -	CONSTRAINT_NONE,
> -	CONSTRAINT_CPUSET,
> -	CONSTRAINT_MEMORY_POLICY,
> -	CONSTRAINT_MEMCG,
> +static const char * const oom_constraint_text[] = {
> +	[CONSTRAINT_NONE] = "CONSTRAINT_NONE",
> +	[CONSTRAINT_CPUSET] = "CONSTRAINT_CPUSET",
> +	[CONSTRAINT_MEMORY_POLICY] = "CONSTRAINT_MEMORY_POLICY",
> +	[CONSTRAINT_MEMCG] = "CONSTRAINT_MEMCG",
>  };
>  
>  /*
> @@ -421,15 +421,21 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
>  
>  static void dump_header(struct oom_control *oc, struct task_struct *p)
>  {
> -	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(oc->nodemask), oc->order,
> +	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%hd\n",
> +		current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order,
>  			current->signal->oom_score_adj);
>  	if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
>  		pr_warn("COMPACTION is disabled!!!\n");
>  
> -	cpuset_print_current_mems_allowed();
>  	dump_stack();
> +
> +	/* one line summary of the oom killer context. */
> +	pr_info("oom-kill:constraint=%s,nodemask=%*pbl",
> +			oom_constraint_text[oc->constraint],
> +			nodemask_pr_args(oc->nodemask));
> +	cpuset_print_current_mems_allowed();
> +	pr_cont(",task=%s,pid=%5d,uid=%5d\n", p->comm, p->pid,
> +		from_kuid(&init_user_ns, task_uid(p)));
>  	if (is_memcg_oom(oc))
>  		mem_cgroup_print_oom_info(oc->memcg, p);
>  	else {
> @@ -973,8 +979,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
>  /*
>   * Determines whether the kernel must panic because of the panic_on_oom sysctl.
>   */
> -static void check_panic_on_oom(struct oom_control *oc,
> -			       enum oom_constraint constraint)
> +static void check_panic_on_oom(struct oom_control *oc)
>  {
>  	if (likely(!sysctl_panic_on_oom))
>  		return;
> @@ -984,7 +989,7 @@ static void check_panic_on_oom(struct oom_control *oc,
>  		 * does not panic for cpuset, mempolicy, or memcg allocation
>  		 * failures.
>  		 */
> -		if (constraint != CONSTRAINT_NONE)
> +		if (oc->constraint != CONSTRAINT_NONE)
>  			return;
>  	}
>  	/* Do not panic for oom kills triggered by sysrq */
> @@ -1021,8 +1026,8 @@ EXPORT_SYMBOL_GPL(unregister_oom_notifier);
>  bool out_of_memory(struct oom_control *oc)
>  {
>  	unsigned long freed = 0;
> -	enum oom_constraint constraint = CONSTRAINT_NONE;
>  
> +	oc->constraint = CONSTRAINT_NONE;
>  	if (oom_killer_disabled)
>  		return false;
>  
> @@ -1057,10 +1062,10 @@ bool out_of_memory(struct oom_control *oc)
>  	 * Check if there were limitations on the allocation (only relevant for
>  	 * NUMA and memcg) that may require different handling.
>  	 */
> -	constraint = constrained_alloc(oc);
> -	if (constraint != CONSTRAINT_MEMORY_POLICY)
> +	oc->constraint = constrained_alloc(oc);
> +	if (oc->constraint != CONSTRAINT_MEMORY_POLICY)
>  		oc->nodemask = NULL;
> -	check_panic_on_oom(oc, constraint);
> +	check_panic_on_oom(oc);
>  
>  	if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task &&
>  	    current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) &&
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 1521100f1e63..194e0763fd5f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3416,13 +3416,13 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
>  	va_start(args, fmt);
>  	vaf.fmt = fmt;
>  	vaf.va = &args;
> -	pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl\n",
> +	pr_warn("%s: %pV,mode:%#x(%pGg),nodemask=%*pbl",
>  			current->comm, &vaf, gfp_mask, &gfp_mask,
>  			nodemask_pr_args(nodemask));
>  	va_end(args);
>  
>  	cpuset_print_current_mems_allowed();
> -
> +	pr_cont("\n");
>  	dump_stack();
>  	warn_alloc_show_mem(gfp_mask, nodemask);
>  }
> -- 
> 2.14.1
> 

-- 
Michal Hocko
SUSE Labs

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