Commit 9b6aa892 authored by Yosry Ahmed's avatar Yosry Ahmed Committed by Lu Jialin
Browse files

memcg: use seq_buf_do_printk() with mem_cgroup_print_oom_meminfo() 

mainline inclusion
from mainline-v6.5-rc1
commit 5b42360c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8C7BS

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5b42360c73b0679505dac6ec44d234cfec61120c

-------------------------------------------------

Currently, we format all the memcg stats into a buffer in
mem_cgroup_print_oom_meminfo() and use pr_info() to dump it to the logs.
However, this buffer is large in size.  Although it is currently working
as intended, ther is a dependency between the memcg stats buffer and the
printk record size limit.

If we add more stats in the future and the buffer becomes larger than the
printk record size limit, or if the prink record size limit is reduced,
the logs may be truncated.

It is safer to use seq_buf_do_printk(), which will automatically break up
the buffer at line breaks and issue small printk() calls.

Refactor the code to move the seq_buf from memory_stat_format() to its
callers, and use seq_buf_do_printk() to print the seq_buf in
mem_cgroup_print_oom_meminfo().

Link: https://lkml.kernel.org/r/20230428132406.2540811-2-yosryahmed@google.com


Signed-off-by: default avatarYosry Ahmed <yosryahmed@google.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Reviewed-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: default avatarShakeel Butt <shakeelb@google.com>
Reviewed-by: default avatarMuchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Conflict:
	mm/memcontrol.c
Signed-off-by: default avatarLu Jialin <lujialin4@huawei.com>
parent b5e03080

mm/memcontrol.c

+22 −21
Original line number Diff line number Diff line
@@ -1514,13 +1514,10 @@ static int __init memory_stats_init(void) 
}

pure_initcall(memory_stats_init);



static void memory_stat_format(struct mem_cgroup *memcg, char *buf, int bufsize)

static void memory_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)

{

	struct seq_buf s;

	int i;



	seq_buf_init(&s, buf, bufsize);



	/*

	 * Provide statistics on the state of the memory subsystem as

	 * well as cumulative event counters that show past behavior.
@@ -1538,47 +1535,47 @@ static void memory_stat_format(struct mem_cgroup *memcg, char *buf, int bufsize) 


		size = memcg_page_state(memcg, memory_stats[i].idx);

		size *= memory_stats[i].ratio;

		seq_buf_printf(&s, "%s %llu\n", memory_stats[i].name, size);

		seq_buf_printf(s, "%s %llu\n", memory_stats[i].name, size);



		if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) {

			size = memcg_page_state(memcg, NR_SLAB_RECLAIMABLE_B) +

			       memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE_B);

			seq_buf_printf(&s, "slab %llu\n", size);

			seq_buf_printf(s, "slab %llu\n", size);

		}

	}



	/* Accumulated memory events */



	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGFAULT),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(PGFAULT),

		       memcg_events(memcg, PGFAULT));

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGMAJFAULT),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(PGMAJFAULT),

		       memcg_events(memcg, PGMAJFAULT));

	seq_buf_printf(&s, "%s %lu\n",  vm_event_name(PGREFILL),

	seq_buf_printf(s, "%s %lu\n",  vm_event_name(PGREFILL),

		       memcg_events(memcg, PGREFILL));

	seq_buf_printf(&s, "pgscan %lu\n",

	seq_buf_printf(s, "pgscan %lu\n",

		       memcg_events(memcg, PGSCAN_KSWAPD) +

		       memcg_events(memcg, PGSCAN_DIRECT));

	seq_buf_printf(&s, "pgsteal %lu\n",

	seq_buf_printf(s, "pgsteal %lu\n",

		       memcg_events(memcg, PGSTEAL_KSWAPD) +

		       memcg_events(memcg, PGSTEAL_DIRECT));

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGACTIVATE),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(PGACTIVATE),

		       memcg_events(memcg, PGACTIVATE));

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGDEACTIVATE),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(PGDEACTIVATE),

		       memcg_events(memcg, PGDEACTIVATE));

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGLAZYFREE),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(PGLAZYFREE),

		       memcg_events(memcg, PGLAZYFREE));

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGLAZYFREED),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(PGLAZYFREED),

		       memcg_events(memcg, PGLAZYFREED));



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(THP_FAULT_ALLOC),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(THP_FAULT_ALLOC),

		       memcg_events(memcg, THP_FAULT_ALLOC));

	seq_buf_printf(&s, "%s %lu\n", vm_event_name(THP_COLLAPSE_ALLOC),

	seq_buf_printf(s, "%s %lu\n", vm_event_name(THP_COLLAPSE_ALLOC),

		       memcg_events(memcg, THP_COLLAPSE_ALLOC));

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



	/* The above should easily fit into one page */

	WARN_ON_ONCE(seq_buf_has_overflowed(&s));

	WARN_ON_ONCE(seq_buf_has_overflowed(s));

}



#define K(x) ((x) << (PAGE_SHIFT-10))
@@ -1617,6 +1614,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) 
	/* Use static buffer, for the caller is holding oom_lock. */

	static char buf[PAGE_SIZE];

	static char pathbuf[PATH_MAX];

	struct seq_buf s;



	lockdep_assert_held(&oom_lock);
@@ -1639,8 +1637,9 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) 
	pr_info("Memory cgroup stats for ");

	pr_cont_cgroup_path(memcg->css.cgroup);

	pr_cont(":");

	memory_stat_format(memcg, buf, sizeof(buf));

	pr_info("%s", buf);

	seq_buf_init(&s, buf, sizeof(buf));

	memory_stat_format(memcg, &s);

	seq_buf_do_printk(&s, KERN_INFO);



	mem_cgroup_print_memfs_info(memcg, pathbuf, NULL);

}
@@ -7425,10 +7424,12 @@ static int memory_stat_show(struct seq_file *m, void *v) 
{

	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);

	char *buf = kmalloc(PAGE_SIZE, GFP_KERNEL);

	struct seq_buf s;



	if (!buf)

		return -ENOMEM;

	memory_stat_format(memcg, buf, PAGE_SIZE);

	seq_buf_init(&s, buf, PAGE_SIZE);

	memory_stat_format(memcg, &s);

	seq_puts(m, buf);

	kfree(buf);

	return 0;