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 */ 15 int sysctl_drop_caches; 16 17 static 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 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || 25 (inode->i_mapping->nrpages == 0)) { 26 spin_unlock(&inode->i_lock); 27 continue; 28 } 29 __iget(inode); 30 spin_unlock(&inode->i_lock); 31 spin_unlock(&sb->s_inode_list_lock); 32 33 invalidate_mapping_pages(inode->i_mapping, 0, -1); 34 iput(toput_inode); 35 toput_inode = inode; 36 37 spin_lock(&sb->s_inode_list_lock); 38 } 39 spin_unlock(&sb->s_inode_list_lock); 40 iput(toput_inode); 41 } 42 43 int drop_caches_sysctl_handler(struct ctl_table *table, int write, 44 void __user *buffer, size_t *length, loff_t *ppos) 45 { 46 int ret; 47 48 ret = proc_dointvec_minmax(table, write, buffer, length, ppos); 49 if (ret) 50 return ret; 51 if (write) { 52 static int stfu; 53 54 if (sysctl_drop_caches & 1) { 55 iterate_supers(drop_pagecache_sb, NULL); 56 count_vm_event(DROP_PAGECACHE); 57 } 58 if (sysctl_drop_caches & 2) { 59 drop_slab(); 60 count_vm_event(DROP_SLAB); 61 } 62 if (!stfu) { 63 pr_info("%s (%d): drop_caches: %d\n", 64 current->comm, task_pid_nr(current), 65 sysctl_drop_caches); 66 } 67 stfu |= sysctl_drop_caches & 4; 68 } 69 return 0; 70 } 71