mm, oom: fix race when specifying a thread as the oom origin

[deliverable/linux.git] / mm / swapfile.c

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 14e254c768fc5090e9c2276085b3c6f96c6255f6..e97a0e5aea912cf0c0109164811d650cc0b2219e 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1443,13 +1443,12 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
        return generic_swapfile_activate(sis, swap_file, span);
 }
 
-static void enable_swap_info(struct swap_info_struct *p, int prio,
+static void _enable_swap_info(struct swap_info_struct *p, int prio,
                                unsigned char *swap_map,
                                unsigned long *frontswap_map)
 {
        int i, prev;
 
-       spin_lock(&swap_lock);
        if (prio >= 0)
                p->prio = prio;
        else
@@ -1472,10 +1471,25 @@ static void enable_swap_info(struct swap_info_struct *p, int prio,
                swap_list.head = swap_list.next = p->type;
        else
                swap_info[prev]->next = p->type;
+}
+
+static void enable_swap_info(struct swap_info_struct *p, int prio,
+                               unsigned char *swap_map,
+                               unsigned long *frontswap_map)
+{
+       spin_lock(&swap_lock);
+       _enable_swap_info(p, prio, swap_map, frontswap_map);
        frontswap_init(p->type);
        spin_unlock(&swap_lock);
 }
 
+static void reinsert_swap_info(struct swap_info_struct *p)
+{
+       spin_lock(&swap_lock);
+       _enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p));
+       spin_unlock(&swap_lock);
+}
+
 SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 {
        struct swap_info_struct *p = NULL;
@@ -1483,8 +1497,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
        struct file *swap_file, *victim;
        struct address_space *mapping;
        struct inode *inode;
-       char *pathname;
-       int oom_score_adj;
+       struct filename *pathname;
        int i, type, prev;
        int err;
 
@@ -1494,12 +1507,10 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
        BUG_ON(!current->mm);
 
        pathname = getname(specialfile);
-       err = PTR_ERR(pathname);
        if (IS_ERR(pathname))
-               goto out;
+               return PTR_ERR(pathname);
 
-       victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
-       putname(pathname);
+       victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0);
        err = PTR_ERR(victim);
        if (IS_ERR(victim))
                goto out;
@@ -1545,19 +1556,13 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
        p->flags &= ~SWP_WRITEOK;
        spin_unlock(&swap_lock);
 
-       oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX);
+       set_current_oom_origin();
        err = try_to_unuse(type, false, 0); /* force all pages to be unused */
-       compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX, oom_score_adj);
+       clear_current_oom_origin();
 
        if (err) {
-               /*
-                * reading p->prio and p->swap_map outside the lock is
-                * safe here because only sys_swapon and sys_swapoff
-                * change them, and there can be no other sys_swapon or
-                * sys_swapoff for this swap_info_struct at this point.
-                */
                /* re-insert swap space back into swap_list */
-               enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p));
+               reinsert_swap_info(p);
                goto out_dput;
        }
 
@@ -1609,6 +1614,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 out_dput:
        filp_close(victim, NULL);
 out:
+       putname(pathname);
        return err;
 }
 
@@ -1936,7 +1942,7 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p,
 SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 {
        struct swap_info_struct *p;
-       char *name;
+       struct filename *name;
        struct file *swap_file = NULL;
        struct address_space *mapping;
        int i;
@@ -1967,7 +1973,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
                name = NULL;
                goto bad_swap;
        }
-       swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
+       swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0);
        if (IS_ERR(swap_file)) {
                error = PTR_ERR(swap_file);
                swap_file = NULL;
@@ -2053,7 +2059,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 
        printk(KERN_INFO "Adding %uk swap on %s.  "
                        "Priority:%d extents:%d across:%lluk %s%s%s\n",
-               p->pages<<(PAGE_SHIFT-10), name, p->prio,
+               p->pages<<(PAGE_SHIFT-10), name->name, p->prio,
                nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
                (p->flags & SWP_SOLIDSTATE) ? "SS" : "",
                (p->flags & SWP_DISCARDABLE) ? "D" : "",