From: Yosry Ahmed yosryahmed@google.com
mainline inclusion from mainline-v6.5-rc1 commit 5b42360c73b0679505dac6ec44d234cfec61120c category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8C7BS
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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: Yosry Ahmed yosryahmed@google.com Acked-by: Michal Hocko mhocko@suse.com Reviewed-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Shakeel Butt shakeelb@google.com Reviewed-by: Muchun 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: Andrew Morton akpm@linux-foundation.org Conflict: mm/memcontrol.c Signed-off-by: Lu Jialin lujialin4@huawei.com --- mm/memcontrol.c | 43 ++++++++++++++++++++++--------------------- 1 file changed, 22 insertions(+), 21 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7f3832cedfdf..6d2685e2839c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1493,13 +1493,10 @@ 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. @@ -1517,47 +1514,47 @@ 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)) @@ -1596,6 +1593,7 @@ 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);
@@ -1618,8 +1616,9 @@ 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); } @@ -6638,10 +6637,12 @@ 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;