1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Implement the manual drop-all-pagecache function
 4 */
 5
 6#include <linux/pagemap.h>
 7#include <linux/kernel.h>
 8#include <linux/mm.h>
 9#include <linux/fs.h>
10#include <linux/writeback.h>
11#include <linux/sysctl.h>
12#include <linux/gfp.h>
13#include <linux/swap.h>
14#include "internal.h"
15
16/* A global variable is a bit ugly, but it keeps the code simple */
17int sysctl_drop_caches;
18
19static void drop_pagecache_sb(struct super_block *sb, void *unused)
20{
21	struct inode *inode, *toput_inode = NULL;
22
23	spin_lock(&sb->s_inode_list_lock);
24	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
25		spin_lock(&inode->i_lock);
26		/*
27		 * We must skip inodes in unusual state. We may also skip
28		 * inodes without pages but we deliberately won't in case
29		 * we need to reschedule to avoid softlockups.
30		 */
31		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
32		    (mapping_empty(inode->i_mapping) && !need_resched())) {
33			spin_unlock(&inode->i_lock);
34			continue;
35		}
36		__iget(inode);
37		spin_unlock(&inode->i_lock);
38		spin_unlock(&sb->s_inode_list_lock);
39
40		invalidate_mapping_pages(inode->i_mapping, 0, -1);
41		iput(toput_inode);
42		toput_inode = inode;
43
44		cond_resched();
45		spin_lock(&sb->s_inode_list_lock);
46	}
47	spin_unlock(&sb->s_inode_list_lock);
48	iput(toput_inode);
49}
50
51int drop_caches_sysctl_handler(struct ctl_table *table, int write,
52		void *buffer, size_t *length, loff_t *ppos)
53{
54	int ret;
55
56	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
57	if (ret)
58		return ret;
59	if (write) {
60		static int stfu;
61
62		if (sysctl_drop_caches & 1) {
63			lru_add_drain_all();
64			iterate_supers(drop_pagecache_sb, NULL);
65			count_vm_event(DROP_PAGECACHE);
66		}
67		if (sysctl_drop_caches & 2) {
68			drop_slab();
69			count_vm_event(DROP_SLAB);
70		}
71		if (!stfu) {
72			pr_info("%s (%d): drop_caches: %d\n",
73				current->comm, task_pid_nr(current),
74				sysctl_drop_caches);
75		}
76		stfu |= sysctl_drop_caches & 4;
77	}
78	return 0;
79}

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Implement the manual drop-all-pagecache function
 4 */
 5
 
 6#include <linux/kernel.h>
 7#include <linux/mm.h>
 8#include <linux/fs.h>
 9#include <linux/writeback.h>
10#include <linux/sysctl.h>
11#include <linux/gfp.h>
 
12#include "internal.h"
13
14/* A global variable is a bit ugly, but it keeps the code simple */
15int sysctl_drop_caches;
16
17static void drop_pagecache_sb(struct super_block *sb, void *unused)
18{
19	struct inode *inode, *toput_inode = NULL;
20
21	spin_lock(&sb->s_inode_list_lock);
22	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
23		spin_lock(&inode->i_lock);
24		/*
25		 * We must skip inodes in unusual state. We may also skip
26		 * inodes without pages but we deliberately won't in case
27		 * we need to reschedule to avoid softlockups.
28		 */
29		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
30		    (inode->i_mapping->nrpages == 0 && !need_resched())) {
31			spin_unlock(&inode->i_lock);
32			continue;
33		}
34		__iget(inode);
35		spin_unlock(&inode->i_lock);
36		spin_unlock(&sb->s_inode_list_lock);
37
38		invalidate_mapping_pages(inode->i_mapping, 0, -1);
39		iput(toput_inode);
40		toput_inode = inode;
41
42		cond_resched();
43		spin_lock(&sb->s_inode_list_lock);
44	}
45	spin_unlock(&sb->s_inode_list_lock);
46	iput(toput_inode);
47}
48
49int drop_caches_sysctl_handler(struct ctl_table *table, int write,
50		void *buffer, size_t *length, loff_t *ppos)
51{
52	int ret;
53
54	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
55	if (ret)
56		return ret;
57	if (write) {
58		static int stfu;
59
60		if (sysctl_drop_caches & 1) {
 
61			iterate_supers(drop_pagecache_sb, NULL);
62			count_vm_event(DROP_PAGECACHE);
63		}
64		if (sysctl_drop_caches & 2) {
65			drop_slab();
66			count_vm_event(DROP_SLAB);
67		}
68		if (!stfu) {
69			pr_info("%s (%d): drop_caches: %d\n",
70				current->comm, task_pid_nr(current),
71				sysctl_drop_caches);
72		}
73		stfu |= sysctl_drop_caches & 4;
74	}
75	return 0;
76}