1 /* 2 * Implement the manual drop-all-pagecache function 3 */ 4 5 #include <linux/kernel.h> 6 #include <linux/mm.h> 7 #include <linux/fs.h> 8 #include <linux/writeback.h> 9 #include <linux/sysctl.h> 10 #include <linux/gfp.h> 11 #include "internal.h" 12 13 /* A global variable is a bit ugly, but it keeps the code simple */ 14 int sysctl_drop_caches; 15 16 static void drop_pagecache_sb(struct super_block *sb, void *unused) 17 { 18 struct inode *inode, *toput_inode = NULL; 19 20 spin_lock(&inode_sb_list_lock); 21 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 22 spin_lock(&inode->i_lock); 23 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || 24 (inode->i_mapping->nrpages == 0)) { 25 spin_unlock(&inode->i_lock); 26 continue; 27 } 28 __iget(inode); 29 spin_unlock(&inode->i_lock); 30 spin_unlock(&inode_sb_list_lock); 31 invalidate_mapping_pages(inode->i_mapping, 0, -1); 32 iput(toput_inode); 33 toput_inode = inode; 34 spin_lock(&inode_sb_list_lock); 35 } 36 spin_unlock(&inode_sb_list_lock); 37 iput(toput_inode); 38 } 39 40 static void drop_slab(void) 41 { 42 int nr_objects; 43 struct shrink_control shrink = { 44 .gfp_mask = GFP_KERNEL, 45 }; 46 47 nodes_setall(shrink.nodes_to_scan); 48 do { 49 nr_objects = shrink_slab(&shrink, 1000, 1000); 50 } while (nr_objects > 10); 51 } 52 53 int drop_caches_sysctl_handler(struct ctl_table *table, int write, 54 void __user *buffer, size_t *length, loff_t *ppos) 55 { 56 int ret; 57 58 ret = proc_dointvec_minmax(table, write, buffer, length, ppos); 59 if (ret) 60 return ret; 61 if (write) { 62 static int stfu; 63 64 if (sysctl_drop_caches & 1) { 65 iterate_supers(drop_pagecache_sb, NULL); 66 count_vm_event(DROP_PAGECACHE); 67 } 68 if (sysctl_drop_caches & 2) { 69 drop_slab(); 70 count_vm_event(DROP_SLAB); 71 } 72 if (!stfu) { 73 pr_info("%s (%d): drop_caches: %d\n", 74 current->comm, task_pid_nr(current), 75 sysctl_drop_caches); 76 } 77 stfu |= sysctl_drop_caches & 4; 78 } 79 return 0; 80 } 81