Commit 009c22bb authored by Yu Liao's avatar Yu Liao Committed by Yongqiang Liu
Browse files

mm: clear_freelist_page: Provide timeout mechanism for worker runtime 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I558LD


CVE: NA

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

In the case of large memory, the clear freelist will hold zone lock
for a long time. As a result, the process may be blocked unless clear
freelist thread exit, and causing the system to be reset by the watchdog.

Provide a mechanism to stop clear freelist threads when elapsed time
exceeds cfp_timeout, which can be set by module_param().

Signed-off-by: default avatarYu Liao <liaoyu15@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarYongqiang Liu <liuyongqiang13@huawei.com>
parent a5aba824

mm/clear_freelist_page.c

+16 −0
Original line number Diff line number Diff line
@@ -13,8 +13,10 @@ 
#include <linux/sched.h>

#include <linux/atomic.h>

#include <linux/nmi.h>

#include <linux/sched/clock.h>

#include <linux/module.h>



#define CFP_DEFAULT_TIMEOUT 2000

#define for_each_populated_zone_pgdat(pgdat, zone) \

	for (zone = pgdat->node_zones;      \

		zone;                  \
@@ -32,6 +34,7 @@ static DECLARE_WAIT_QUEUE_HEAD(clear_freelist_wait); 
static DEFINE_MUTEX(clear_freelist_lock);

static atomic_t clear_freelist_workers;

static atomic_t clear_pages_num;

static ulong cfp_timeout_ms = CFP_DEFAULT_TIMEOUT;

static int one = 1;



/*
@@ -51,15 +54,25 @@ static struct zone *next_pgdat_zone(struct zone *zone) 
static void clear_pgdat_freelist_pages(struct work_struct *work)

{

	struct pgdat_entry *entry = container_of(work, struct pgdat_entry, work);

	u64 cfp_timeout_ns = cfp_timeout_ms * NSEC_PER_MSEC;

	struct pglist_data *pgdat = entry->pgdat;

	unsigned long flags, order, t;

	struct page *page;

	struct zone *zone;

	u64 start, now;



	start = sched_clock();



	for_each_populated_zone_pgdat(pgdat, zone) {

		spin_lock_irqsave(&zone->lock, flags);

		for_each_migratetype_order(order, t) {

			list_for_each_entry(page, &zone->free_area[order].free_list[t], lru) {

				now = sched_clock();

				if (unlikely(now - start > cfp_timeout_ns)) {

					spin_unlock_irqrestore(&zone->lock, flags);

					goto out;

				}



#ifdef CONFIG_KMAP_LOCAL

				int i;
@@ -77,6 +90,8 @@ static void clear_pgdat_freelist_pages(struct work_struct *work) 


		cond_resched();

	}



out:

	kfree(entry);



	if (atomic_dec_and_test(&clear_freelist_workers))
@@ -170,3 +185,4 @@ static int __init clear_freelist_init(void) 
	return 0;

}

module_init(clear_freelist_init);

module_param(cfp_timeout_ms, ulong, 0644);