1 // SPDX-License-Identifier: GPL-2.0
3 * Implement the manual drop-all-pagecache function
6 #include <linux/kernel.h>
9 #include <linux/writeback.h>
10 #include <linux/sysctl.h>
11 #include <linux/gfp.h>
14 /* A global variable is a bit ugly, but it keeps the code simple */
15 int sysctl_drop_caches;
17 static void drop_pagecache_sb(struct super_block *sb, void *unused)
19 struct inode *inode, *toput_inode = NULL;
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);
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.
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);
35 spin_unlock(&inode->i_lock);
36 spin_unlock(&sb->s_inode_list_lock);
38 invalidate_mapping_pages(inode->i_mapping, 0, -1);
43 spin_lock(&sb->s_inode_list_lock);
45 spin_unlock(&sb->s_inode_list_lock);
49 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
50 void *buffer, size_t *length, loff_t *ppos)
54 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
60 if (sysctl_drop_caches & 1) {
61 iterate_supers(drop_pagecache_sb, NULL);
62 count_vm_event(DROP_PAGECACHE);
64 if (sysctl_drop_caches & 2) {
66 count_vm_event(DROP_SLAB);
69 pr_info("%s (%d): drop_caches: %d\n",
70 current->comm, task_pid_nr(current),
73 stfu |= sysctl_drop_caches & 4;