android_kernel_xiaomi_sm8350/kernel/cpuset.c
Eric Dumazet 5160ee6fc8 [PATCH] shrink dentry struct
Some long time ago, dentry struct was carefully tuned so that on 32 bits
UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple
of memory cache lines.

Then RCU was added and dentry struct enlarged by two pointers, with nice
results for SMP, but not so good on UP, because breaking the above tuning
(128 + 8 = 136 bytes)

This patch reverts this unwanted side effect, by using an union (d_u),
where d_rcu and d_child are placed so that these two fields can share their
memory needs.

At the time d_free() is called (and d_rcu is really used), d_child is known
to be empty and not touched by the dentry freeing.

Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so
the previous content of d_child is not needed if said dentry was unhashed
but still accessed by a CPU because of RCU constraints)

As dentry cache easily contains millions of entries, a size reduction is
worth the extra complexity of the ugly C union.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Paul Jackson <pj@sgi.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Cc: James Morris <jmorris@namei.org>
Cc: Stephen Smalley <sds@epoch.ncsc.mil>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 20:13:58 -08:00

2294 lines
64 KiB
C

/*
* kernel/cpuset.c
*
* Processor and Memory placement constraints for sets of tasks.
*
* Copyright (C) 2003 BULL SA.
* Copyright (C) 2004 Silicon Graphics, Inc.
*
* Portions derived from Patrick Mochel's sysfs code.
* sysfs is Copyright (c) 2001-3 Patrick Mochel
* Portions Copyright (c) 2004 Silicon Graphics, Inc.
*
* 2003-10-10 Written by Simon Derr <simon.derr@bull.net>
* 2003-10-22 Updates by Stephen Hemminger.
* 2004 May-July Rework by Paul Jackson <pj@sgi.com>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of the Linux
* distribution for more details.
*/
#include <linux/config.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/cpuset.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/mempolicy.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/backing-dev.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>
#define CPUSET_SUPER_MAGIC 0x27e0eb
/*
* Tracks how many cpusets are currently defined in system.
* When there is only one cpuset (the root cpuset) we can
* short circuit some hooks.
*/
int number_of_cpusets __read_mostly;
/* See "Frequency meter" comments, below. */
struct fmeter {
int cnt; /* unprocessed events count */
int val; /* most recent output value */
time_t time; /* clock (secs) when val computed */
spinlock_t lock; /* guards read or write of above */
};
struct cpuset {
unsigned long flags; /* "unsigned long" so bitops work */
cpumask_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
/*
* Count is atomic so can incr (fork) or decr (exit) without a lock.
*/
atomic_t count; /* count tasks using this cpuset */
/*
* We link our 'sibling' struct into our parents 'children'.
* Our children link their 'sibling' into our 'children'.
*/
struct list_head sibling; /* my parents children */
struct list_head children; /* my children */
struct cpuset *parent; /* my parent */
struct dentry *dentry; /* cpuset fs entry */
/*
* Copy of global cpuset_mems_generation as of the most
* recent time this cpuset changed its mems_allowed.
*/
int mems_generation;
struct fmeter fmeter; /* memory_pressure filter */
};
/* bits in struct cpuset flags field */
typedef enum {
CS_CPU_EXCLUSIVE,
CS_MEM_EXCLUSIVE,
CS_MEMORY_MIGRATE,
CS_REMOVED,
CS_NOTIFY_ON_RELEASE
} cpuset_flagbits_t;
/* convenient tests for these bits */
static inline int is_cpu_exclusive(const struct cpuset *cs)
{
return !!test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
}
static inline int is_mem_exclusive(const struct cpuset *cs)
{
return !!test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
}
static inline int is_removed(const struct cpuset *cs)
{
return !!test_bit(CS_REMOVED, &cs->flags);
}
static inline int notify_on_release(const struct cpuset *cs)
{
return !!test_bit(CS_NOTIFY_ON_RELEASE, &cs->flags);
}
static inline int is_memory_migrate(const struct cpuset *cs)
{
return !!test_bit(CS_MEMORY_MIGRATE, &cs->flags);
}
/*
* Increment this atomic integer everytime any cpuset changes its
* mems_allowed value. Users of cpusets can track this generation
* number, and avoid having to lock and reload mems_allowed unless
* the cpuset they're using changes generation.
*
* A single, global generation is needed because attach_task() could
* reattach a task to a different cpuset, which must not have its
* generation numbers aliased with those of that tasks previous cpuset.
*
* Generations are needed for mems_allowed because one task cannot
* modify anothers memory placement. So we must enable every task,
* on every visit to __alloc_pages(), to efficiently check whether
* its current->cpuset->mems_allowed has changed, requiring an update
* of its current->mems_allowed.
*/
static atomic_t cpuset_mems_generation = ATOMIC_INIT(1);
static struct cpuset top_cpuset = {
.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
.cpus_allowed = CPU_MASK_ALL,
.mems_allowed = NODE_MASK_ALL,
.count = ATOMIC_INIT(0),
.sibling = LIST_HEAD_INIT(top_cpuset.sibling),
.children = LIST_HEAD_INIT(top_cpuset.children),
};
static struct vfsmount *cpuset_mount;
static struct super_block *cpuset_sb;
/*
* We have two global cpuset semaphores below. They can nest.
* It is ok to first take manage_sem, then nest callback_sem. We also
* require taking task_lock() when dereferencing a tasks cpuset pointer.
* See "The task_lock() exception", at the end of this comment.
*
* A task must hold both semaphores to modify cpusets. If a task
* holds manage_sem, then it blocks others wanting that semaphore,
* ensuring that it is the only task able to also acquire callback_sem
* and be able to modify cpusets. It can perform various checks on
* the cpuset structure first, knowing nothing will change. It can
* also allocate memory while just holding manage_sem. While it is
* performing these checks, various callback routines can briefly
* acquire callback_sem to query cpusets. Once it is ready to make
* the changes, it takes callback_sem, blocking everyone else.
*
* Calls to the kernel memory allocator can not be made while holding
* callback_sem, as that would risk double tripping on callback_sem
* from one of the callbacks into the cpuset code from within
* __alloc_pages().
*
* If a task is only holding callback_sem, then it has read-only
* access to cpusets.
*
* The task_struct fields mems_allowed and mems_generation may only
* be accessed in the context of that task, so require no locks.
*
* Any task can increment and decrement the count field without lock.
* So in general, code holding manage_sem or callback_sem can't rely
* on the count field not changing. However, if the count goes to
* zero, then only attach_task(), which holds both semaphores, can
* increment it again. Because a count of zero means that no tasks
* are currently attached, therefore there is no way a task attached
* to that cpuset can fork (the other way to increment the count).
* So code holding manage_sem or callback_sem can safely assume that
* if the count is zero, it will stay zero. Similarly, if a task
* holds manage_sem or callback_sem on a cpuset with zero count, it
* knows that the cpuset won't be removed, as cpuset_rmdir() needs
* both of those semaphores.
*
* A possible optimization to improve parallelism would be to make
* callback_sem a R/W semaphore (rwsem), allowing the callback routines
* to proceed in parallel, with read access, until the holder of
* manage_sem needed to take this rwsem for exclusive write access
* and modify some cpusets.
*
* The cpuset_common_file_write handler for operations that modify
* the cpuset hierarchy holds manage_sem across the entire operation,
* single threading all such cpuset modifications across the system.
*
* The cpuset_common_file_read() handlers only hold callback_sem across
* small pieces of code, such as when reading out possibly multi-word
* cpumasks and nodemasks.
*
* The fork and exit callbacks cpuset_fork() and cpuset_exit(), don't
* (usually) take either semaphore. These are the two most performance
* critical pieces of code here. The exception occurs on cpuset_exit(),
* when a task in a notify_on_release cpuset exits. Then manage_sem
* is taken, and if the cpuset count is zero, a usermode call made
* to /sbin/cpuset_release_agent with the name of the cpuset (path
* relative to the root of cpuset file system) as the argument.
*
* A cpuset can only be deleted if both its 'count' of using tasks
* is zero, and its list of 'children' cpusets is empty. Since all
* tasks in the system use _some_ cpuset, and since there is always at
* least one task in the system (init, pid == 1), therefore, top_cpuset
* always has either children cpusets and/or using tasks. So we don't
* need a special hack to ensure that top_cpuset cannot be deleted.
*
* The above "Tale of Two Semaphores" would be complete, but for:
*
* The task_lock() exception
*
* The need for this exception arises from the action of attach_task(),
* which overwrites one tasks cpuset pointer with another. It does
* so using both semaphores, however there are several performance
* critical places that need to reference task->cpuset without the
* expense of grabbing a system global semaphore. Therefore except as
* noted below, when dereferencing or, as in attach_task(), modifying
* a tasks cpuset pointer we use task_lock(), which acts on a spinlock
* (task->alloc_lock) already in the task_struct routinely used for
* such matters.
*
* P.S. One more locking exception. RCU is used to guard the
* update of a tasks cpuset pointer by attach_task() and the
* access of task->cpuset->mems_generation via that pointer in
* the routine cpuset_update_task_memory_state().
*/
static DECLARE_MUTEX(manage_sem);
static DECLARE_MUTEX(callback_sem);
/*
* A couple of forward declarations required, due to cyclic reference loop:
* cpuset_mkdir -> cpuset_create -> cpuset_populate_dir -> cpuset_add_file
* -> cpuset_create_file -> cpuset_dir_inode_operations -> cpuset_mkdir.
*/
static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode);
static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry);
static struct backing_dev_info cpuset_backing_dev_info = {
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
};
static struct inode *cpuset_new_inode(mode_t mode)
{
struct inode *inode = new_inode(cpuset_sb);
if (inode) {
inode->i_mode = mode;
inode->i_uid = current->fsuid;
inode->i_gid = current->fsgid;
inode->i_blksize = PAGE_CACHE_SIZE;
inode->i_blocks = 0;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_mapping->backing_dev_info = &cpuset_backing_dev_info;
}
return inode;
}
static void cpuset_diput(struct dentry *dentry, struct inode *inode)
{
/* is dentry a directory ? if so, kfree() associated cpuset */
if (S_ISDIR(inode->i_mode)) {
struct cpuset *cs = dentry->d_fsdata;
BUG_ON(!(is_removed(cs)));
kfree(cs);
}
iput(inode);
}
static struct dentry_operations cpuset_dops = {
.d_iput = cpuset_diput,
};
static struct dentry *cpuset_get_dentry(struct dentry *parent, const char *name)
{
struct dentry *d = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(d))
d->d_op = &cpuset_dops;
return d;
}
static void remove_dir(struct dentry *d)
{
struct dentry *parent = dget(d->d_parent);
d_delete(d);
simple_rmdir(parent->d_inode, d);
dput(parent);
}
/*
* NOTE : the dentry must have been dget()'ed
*/
static void cpuset_d_remove_dir(struct dentry *dentry)
{
struct list_head *node;
spin_lock(&dcache_lock);
node = dentry->d_subdirs.next;
while (node != &dentry->d_subdirs) {
struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
list_del_init(node);
if (d->d_inode) {
d = dget_locked(d);
spin_unlock(&dcache_lock);
d_delete(d);
simple_unlink(dentry->d_inode, d);
dput(d);
spin_lock(&dcache_lock);
}
node = dentry->d_subdirs.next;
}
list_del_init(&dentry->d_u.d_child);
spin_unlock(&dcache_lock);
remove_dir(dentry);
}
static struct super_operations cpuset_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
};
static int cpuset_fill_super(struct super_block *sb, void *unused_data,
int unused_silent)
{
struct inode *inode;
struct dentry *root;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = CPUSET_SUPER_MAGIC;
sb->s_op = &cpuset_ops;
cpuset_sb = sb;
inode = cpuset_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR);
if (inode) {
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directories start off with i_nlink == 2 (for "." entry) */
inode->i_nlink++;
} else {
return -ENOMEM;
}
root = d_alloc_root(inode);
if (!root) {
iput(inode);
return -ENOMEM;
}
sb->s_root = root;
return 0;
}
static struct super_block *cpuset_get_sb(struct file_system_type *fs_type,
int flags, const char *unused_dev_name,
void *data)
{
return get_sb_single(fs_type, flags, data, cpuset_fill_super);
}
static struct file_system_type cpuset_fs_type = {
.name = "cpuset",
.get_sb = cpuset_get_sb,
.kill_sb = kill_litter_super,
};
/* struct cftype:
*
* The files in the cpuset filesystem mostly have a very simple read/write
* handling, some common function will take care of it. Nevertheless some cases
* (read tasks) are special and therefore I define this structure for every
* kind of file.
*
*
* When reading/writing to a file:
* - the cpuset to use in file->f_dentry->d_parent->d_fsdata
* - the 'cftype' of the file is file->f_dentry->d_fsdata
*/
struct cftype {
char *name;
int private;
int (*open) (struct inode *inode, struct file *file);
ssize_t (*read) (struct file *file, char __user *buf, size_t nbytes,
loff_t *ppos);
int (*write) (struct file *file, const char __user *buf, size_t nbytes,
loff_t *ppos);
int (*release) (struct inode *inode, struct file *file);
};
static inline struct cpuset *__d_cs(struct dentry *dentry)
{
return dentry->d_fsdata;
}
static inline struct cftype *__d_cft(struct dentry *dentry)
{
return dentry->d_fsdata;
}
/*
* Call with manage_sem held. Writes path of cpuset into buf.
* Returns 0 on success, -errno on error.
*/
static int cpuset_path(const struct cpuset *cs, char *buf, int buflen)
{
char *start;
start = buf + buflen;
*--start = '\0';
for (;;) {
int len = cs->dentry->d_name.len;
if ((start -= len) < buf)
return -ENAMETOOLONG;
memcpy(start, cs->dentry->d_name.name, len);
cs = cs->parent;
if (!cs)
break;
if (!cs->parent)
continue;
if (--start < buf)
return -ENAMETOOLONG;
*start = '/';
}
memmove(buf, start, buf + buflen - start);
return 0;
}
/*
* Notify userspace when a cpuset is released, by running
* /sbin/cpuset_release_agent with the name of the cpuset (path
* relative to the root of cpuset file system) as the argument.
*
* Most likely, this user command will try to rmdir this cpuset.
*
* This races with the possibility that some other task will be
* attached to this cpuset before it is removed, or that some other
* user task will 'mkdir' a child cpuset of this cpuset. That's ok.
* The presumed 'rmdir' will fail quietly if this cpuset is no longer
* unused, and this cpuset will be reprieved from its death sentence,
* to continue to serve a useful existence. Next time it's released,
* we will get notified again, if it still has 'notify_on_release' set.
*
* The final arg to call_usermodehelper() is 0, which means don't
* wait. The separate /sbin/cpuset_release_agent task is forked by
* call_usermodehelper(), then control in this thread returns here,
* without waiting for the release agent task. We don't bother to
* wait because the caller of this routine has no use for the exit
* status of the /sbin/cpuset_release_agent task, so no sense holding
* our caller up for that.
*
* When we had only one cpuset semaphore, we had to call this
* without holding it, to avoid deadlock when call_usermodehelper()
* allocated memory. With two locks, we could now call this while
* holding manage_sem, but we still don't, so as to minimize
* the time manage_sem is held.
*/
static void cpuset_release_agent(const char *pathbuf)
{
char *argv[3], *envp[3];
int i;
if (!pathbuf)
return;
i = 0;
argv[i++] = "/sbin/cpuset_release_agent";
argv[i++] = (char *)pathbuf;
argv[i] = NULL;
i = 0;
/* minimal command environment */
envp[i++] = "HOME=/";
envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
envp[i] = NULL;
call_usermodehelper(argv[0], argv, envp, 0);
kfree(pathbuf);
}
/*
* Either cs->count of using tasks transitioned to zero, or the
* cs->children list of child cpusets just became empty. If this
* cs is notify_on_release() and now both the user count is zero and
* the list of children is empty, prepare cpuset path in a kmalloc'd
* buffer, to be returned via ppathbuf, so that the caller can invoke
* cpuset_release_agent() with it later on, once manage_sem is dropped.
* Call here with manage_sem held.
*
* This check_for_release() routine is responsible for kmalloc'ing
* pathbuf. The above cpuset_release_agent() is responsible for
* kfree'ing pathbuf. The caller of these routines is responsible
* for providing a pathbuf pointer, initialized to NULL, then
* calling check_for_release() with manage_sem held and the address
* of the pathbuf pointer, then dropping manage_sem, then calling
* cpuset_release_agent() with pathbuf, as set by check_for_release().
*/
static void check_for_release(struct cpuset *cs, char **ppathbuf)
{
if (notify_on_release(cs) && atomic_read(&cs->count) == 0 &&
list_empty(&cs->children)) {
char *buf;
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!buf)
return;
if (cpuset_path(cs, buf, PAGE_SIZE) < 0)
kfree(buf);
else
*ppathbuf = buf;
}
}
/*
* Return in *pmask the portion of a cpusets's cpus_allowed that
* are online. If none are online, walk up the cpuset hierarchy
* until we find one that does have some online cpus. If we get
* all the way to the top and still haven't found any online cpus,
* return cpu_online_map. Or if passed a NULL cs from an exit'ing
* task, return cpu_online_map.
*
* One way or another, we guarantee to return some non-empty subset
* of cpu_online_map.
*
* Call with callback_sem held.
*/
static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask)
{
while (cs && !cpus_intersects(cs->cpus_allowed, cpu_online_map))
cs = cs->parent;
if (cs)
cpus_and(*pmask, cs->cpus_allowed, cpu_online_map);
else
*pmask = cpu_online_map;
BUG_ON(!cpus_intersects(*pmask, cpu_online_map));
}
/*
* Return in *pmask the portion of a cpusets's mems_allowed that
* are online. If none are online, walk up the cpuset hierarchy
* until we find one that does have some online mems. If we get
* all the way to the top and still haven't found any online mems,
* return node_online_map.
*
* One way or another, we guarantee to return some non-empty subset
* of node_online_map.
*
* Call with callback_sem held.
*/
static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
{
while (cs && !nodes_intersects(cs->mems_allowed, node_online_map))
cs = cs->parent;
if (cs)
nodes_and(*pmask, cs->mems_allowed, node_online_map);
else
*pmask = node_online_map;
BUG_ON(!nodes_intersects(*pmask, node_online_map));
}
/**
* cpuset_update_task_memory_state - update task memory placement
*
* If the current tasks cpusets mems_allowed changed behind our
* backs, update current->mems_allowed, mems_generation and task NUMA
* mempolicy to the new value.
*
* Task mempolicy is updated by rebinding it relative to the
* current->cpuset if a task has its memory placement changed.
* Do not call this routine if in_interrupt().
*
* Call without callback_sem or task_lock() held. May be called
* with or without manage_sem held. Doesn't need task_lock to guard
* against another task changing a non-NULL cpuset pointer to NULL,
* as that is only done by a task on itself, and if the current task
* is here, it is not simultaneously in the exit code NULL'ing its
* cpuset pointer. This routine also might acquire callback_sem and
* current->mm->mmap_sem during call.
*
* Reading current->cpuset->mems_generation doesn't need task_lock
* to guard the current->cpuset derefence, because it is guarded
* from concurrent freeing of current->cpuset by attach_task(),
* using RCU.
*
* The rcu_dereference() is technically probably not needed,
* as I don't actually mind if I see a new cpuset pointer but
* an old value of mems_generation. However this really only
* matters on alpha systems using cpusets heavily. If I dropped
* that rcu_dereference(), it would save them a memory barrier.
* For all other arch's, rcu_dereference is a no-op anyway, and for
* alpha systems not using cpusets, another planned optimization,
* avoiding the rcu critical section for tasks in the root cpuset
* which is statically allocated, so can't vanish, will make this
* irrelevant. Better to use RCU as intended, than to engage in
* some cute trick to save a memory barrier that is impossible to
* test, for alpha systems using cpusets heavily, which might not
* even exist.
*
* This routine is needed to update the per-task mems_allowed data,
* within the tasks context, when it is trying to allocate memory
* (in various mm/mempolicy.c routines) and notices that some other
* task has been modifying its cpuset.
*/
void cpuset_update_task_memory_state()
{
int my_cpusets_mem_gen;
struct task_struct *tsk = current;
struct cpuset *cs;
if (tsk->cpuset == &top_cpuset) {
/* Don't need rcu for top_cpuset. It's never freed. */
my_cpusets_mem_gen = top_cpuset.mems_generation;
} else {
rcu_read_lock();
cs = rcu_dereference(tsk->cpuset);
my_cpusets_mem_gen = cs->mems_generation;
rcu_read_unlock();
}
if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
down(&callback_sem);
task_lock(tsk);
cs = tsk->cpuset; /* Maybe changed when task not locked */
guarantee_online_mems(cs, &tsk->mems_allowed);
tsk->cpuset_mems_generation = cs->mems_generation;
task_unlock(tsk);
up(&callback_sem);
mpol_rebind_task(tsk, &tsk->mems_allowed);
}
}
/*
* is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
*
* One cpuset is a subset of another if all its allowed CPUs and
* Memory Nodes are a subset of the other, and its exclusive flags
* are only set if the other's are set. Call holding manage_sem.
*/
static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
{
return cpus_subset(p->cpus_allowed, q->cpus_allowed) &&
nodes_subset(p->mems_allowed, q->mems_allowed) &&
is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
is_mem_exclusive(p) <= is_mem_exclusive(q);
}
/*
* validate_change() - Used to validate that any proposed cpuset change
* follows the structural rules for cpusets.
*
* If we replaced the flag and mask values of the current cpuset
* (cur) with those values in the trial cpuset (trial), would
* our various subset and exclusive rules still be valid? Presumes
* manage_sem held.
*
* 'cur' is the address of an actual, in-use cpuset. Operations
* such as list traversal that depend on the actual address of the
* cpuset in the list must use cur below, not trial.
*
* 'trial' is the address of bulk structure copy of cur, with
* perhaps one or more of the fields cpus_allowed, mems_allowed,
* or flags changed to new, trial values.
*
* Return 0 if valid, -errno if not.
*/
static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
{
struct cpuset *c, *par;
/* Each of our child cpusets must be a subset of us */
list_for_each_entry(c, &cur->children, sibling) {
if (!is_cpuset_subset(c, trial))
return -EBUSY;
}
/* Remaining checks don't apply to root cpuset */
if ((par = cur->parent) == NULL)
return 0;
/* We must be a subset of our parent cpuset */
if (!is_cpuset_subset(trial, par))
return -EACCES;
/* If either I or some sibling (!= me) is exclusive, we can't overlap */
list_for_each_entry(c, &par->children, sibling) {
if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
c != cur &&
cpus_intersects(trial->cpus_allowed, c->cpus_allowed))
return -EINVAL;
if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
c != cur &&
nodes_intersects(trial->mems_allowed, c->mems_allowed))
return -EINVAL;
}
return 0;
}
/*
* For a given cpuset cur, partition the system as follows
* a. All cpus in the parent cpuset's cpus_allowed that are not part of any
* exclusive child cpusets
* b. All cpus in the current cpuset's cpus_allowed that are not part of any
* exclusive child cpusets
* Build these two partitions by calling partition_sched_domains
*
* Call with manage_sem held. May nest a call to the
* lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
*/
static void update_cpu_domains(struct cpuset *cur)
{
struct cpuset *c, *par = cur->parent;
cpumask_t pspan, cspan;
if (par == NULL || cpus_empty(cur->cpus_allowed))
return;
/*
* Get all cpus from parent's cpus_allowed not part of exclusive
* children
*/
pspan = par->cpus_allowed;
list_for_each_entry(c, &par->children, sibling) {
if (is_cpu_exclusive(c))
cpus_andnot(pspan, pspan, c->cpus_allowed);
}
if (is_removed(cur) || !is_cpu_exclusive(cur)) {
cpus_or(pspan, pspan, cur->cpus_allowed);
if (cpus_equal(pspan, cur->cpus_allowed))
return;
cspan = CPU_MASK_NONE;
} else {
if (cpus_empty(pspan))
return;
cspan = cur->cpus_allowed;
/*
* Get all cpus from current cpuset's cpus_allowed not part
* of exclusive children
*/
list_for_each_entry(c, &cur->children, sibling) {
if (is_cpu_exclusive(c))
cpus_andnot(cspan, cspan, c->cpus_allowed);
}
}
lock_cpu_hotplug();
partition_sched_domains(&pspan, &cspan);
unlock_cpu_hotplug();
}
/*
* Call with manage_sem held. May take callback_sem during call.
*/
static int update_cpumask(struct cpuset *cs, char *buf)
{
struct cpuset trialcs;
int retval, cpus_unchanged;
trialcs = *cs;
retval = cpulist_parse(buf, trialcs.cpus_allowed);
if (retval < 0)
return retval;
cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
if (cpus_empty(trialcs.cpus_allowed))
return -ENOSPC;
retval = validate_change(cs, &trialcs);
if (retval < 0)
return retval;
cpus_unchanged = cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed);
down(&callback_sem);
cs->cpus_allowed = trialcs.cpus_allowed;
up(&callback_sem);
if (is_cpu_exclusive(cs) && !cpus_unchanged)
update_cpu_domains(cs);
return 0;
}
/*
* Handle user request to change the 'mems' memory placement
* of a cpuset. Needs to validate the request, update the
* cpusets mems_allowed and mems_generation, and for each
* task in the cpuset, rebind any vma mempolicies and if
* the cpuset is marked 'memory_migrate', migrate the tasks
* pages to the new memory.
*
* Call with manage_sem held. May take callback_sem during call.
* Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
* lock each such tasks mm->mmap_sem, scan its vma's and rebind
* their mempolicies to the cpusets new mems_allowed.
*/
static int update_nodemask(struct cpuset *cs, char *buf)
{
struct cpuset trialcs;
nodemask_t oldmem;
struct task_struct *g, *p;
struct mm_struct **mmarray;
int i, n, ntasks;
int migrate;
int fudge;
int retval;
trialcs = *cs;
retval = nodelist_parse(buf, trialcs.mems_allowed);
if (retval < 0)
goto done;
nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
oldmem = cs->mems_allowed;
if (nodes_equal(oldmem, trialcs.mems_allowed)) {
retval = 0; /* Too easy - nothing to do */
goto done;
}
if (nodes_empty(trialcs.mems_allowed)) {
retval = -ENOSPC;
goto done;
}
retval = validate_change(cs, &trialcs);
if (retval < 0)
goto done;
down(&callback_sem);
cs->mems_allowed = trialcs.mems_allowed;
atomic_inc(&cpuset_mems_generation);
cs->mems_generation = atomic_read(&cpuset_mems_generation);
up(&callback_sem);
set_cpuset_being_rebound(cs); /* causes mpol_copy() rebind */
fudge = 10; /* spare mmarray[] slots */
fudge += cpus_weight(cs->cpus_allowed); /* imagine one fork-bomb/cpu */
retval = -ENOMEM;
/*
* Allocate mmarray[] to hold mm reference for each task
* in cpuset cs. Can't kmalloc GFP_KERNEL while holding
* tasklist_lock. We could use GFP_ATOMIC, but with a
* few more lines of code, we can retry until we get a big
* enough mmarray[] w/o using GFP_ATOMIC.
*/
while (1) {
ntasks = atomic_read(&cs->count); /* guess */
ntasks += fudge;
mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
if (!mmarray)
goto done;
write_lock_irq(&tasklist_lock); /* block fork */
if (atomic_read(&cs->count) <= ntasks)
break; /* got enough */
write_unlock_irq(&tasklist_lock); /* try again */
kfree(mmarray);
}
n = 0;
/* Load up mmarray[] with mm reference for each task in cpuset. */
do_each_thread(g, p) {
struct mm_struct *mm;
if (n >= ntasks) {
printk(KERN_WARNING
"Cpuset mempolicy rebind incomplete.\n");
continue;
}
if (p->cpuset != cs)
continue;
mm = get_task_mm(p);
if (!mm)
continue;
mmarray[n++] = mm;
} while_each_thread(g, p);
write_unlock_irq(&tasklist_lock);
/*
* Now that we've dropped the tasklist spinlock, we can
* rebind the vma mempolicies of each mm in mmarray[] to their
* new cpuset, and release that mm. The mpol_rebind_mm()
* call takes mmap_sem, which we couldn't take while holding
* tasklist_lock. Forks can happen again now - the mpol_copy()
* cpuset_being_rebound check will catch such forks, and rebind
* their vma mempolicies too. Because we still hold the global
* cpuset manage_sem, we know that no other rebind effort will
* be contending for the global variable cpuset_being_rebound.
* It's ok if we rebind the same mm twice; mpol_rebind_mm()
* is idempotent. Also migrate pages in each mm to new nodes.
*/
migrate = is_memory_migrate(cs);
for (i = 0; i < n; i++) {
struct mm_struct *mm = mmarray[i];
mpol_rebind_mm(mm, &cs->mems_allowed);
if (migrate) {
do_migrate_pages(mm, &oldmem, &cs->mems_allowed,
MPOL_MF_MOVE_ALL);
}
mmput(mm);
}
/* We're done rebinding vma's to this cpusets new mems_allowed. */
kfree(mmarray);
set_cpuset_being_rebound(NULL);
retval = 0;
done:
return retval;
}
/*
* Call with manage_sem held.
*/
static int update_memory_pressure_enabled(struct cpuset *cs, char *buf)
{
if (simple_strtoul(buf, NULL, 10) != 0)
cpuset_memory_pressure_enabled = 1;
else
cpuset_memory_pressure_enabled = 0;
return 0;
}
/*
* update_flag - read a 0 or a 1 in a file and update associated flag
* bit: the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE,
* CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE)
* cs: the cpuset to update
* buf: the buffer where we read the 0 or 1
*
* Call with manage_sem held.
*/
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf)
{
int turning_on;
struct cpuset trialcs;
int err, cpu_exclusive_changed;
turning_on = (simple_strtoul(buf, NULL, 10) != 0);
trialcs = *cs;
if (turning_on)
set_bit(bit, &trialcs.flags);
else
clear_bit(bit, &trialcs.flags);
err = validate_change(cs, &trialcs);
if (err < 0)
return err;
cpu_exclusive_changed =
(is_cpu_exclusive(cs) != is_cpu_exclusive(&trialcs));
down(&callback_sem);
if (turning_on)
set_bit(bit, &cs->flags);
else
clear_bit(bit, &cs->flags);
up(&callback_sem);
if (cpu_exclusive_changed)
update_cpu_domains(cs);
return 0;
}
/*
* Frequency meter - How fast is some event occuring?
*
* These routines manage a digitally filtered, constant time based,
* event frequency meter. There are four routines:
* fmeter_init() - initialize a frequency meter.
* fmeter_markevent() - called each time the event happens.
* fmeter_getrate() - returns the recent rate of such events.
* fmeter_update() - internal routine used to update fmeter.
*
* A common data structure is passed to each of these routines,
* which is used to keep track of the state required to manage the
* frequency meter and its digital filter.
*
* The filter works on the number of events marked per unit time.
* The filter is single-pole low-pass recursive (IIR). The time unit
* is 1 second. Arithmetic is done using 32-bit integers scaled to
* simulate 3 decimal digits of precision (multiplied by 1000).
*
* With an FM_COEF of 933, and a time base of 1 second, the filter
* has a half-life of 10 seconds, meaning that if the events quit
* happening, then the rate returned from the fmeter_getrate()
* will be cut in half each 10 seconds, until it converges to zero.
*
* It is not worth doing a real infinitely recursive filter. If more
* than FM_MAXTICKS ticks have elapsed since the last filter event,
* just compute FM_MAXTICKS ticks worth, by which point the level
* will be stable.
*
* Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
* arithmetic overflow in the fmeter_update() routine.
*
* Given the simple 32 bit integer arithmetic used, this meter works
* best for reporting rates between one per millisecond (msec) and
* one per 32 (approx) seconds. At constant rates faster than one
* per msec it maxes out at values just under 1,000,000. At constant
* rates between one per msec, and one per second it will stabilize
* to a value N*1000, where N is the rate of events per second.
* At constant rates between one per second and one per 32 seconds,
* it will be choppy, moving up on the seconds that have an event,
* and then decaying until the next event. At rates slower than
* about one in 32 seconds, it decays all the way back to zero between
* each event.
*/
#define FM_COEF 933 /* coefficient for half-life of 10 secs */
#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
#define FM_SCALE 1000 /* faux fixed point scale */
/* Initialize a frequency meter */
static void fmeter_init(struct fmeter *fmp)
{
fmp->cnt = 0;
fmp->val = 0;
fmp->time = 0;
spin_lock_init(&fmp->lock);
}
/* Internal meter update - process cnt events and update value */
static void fmeter_update(struct fmeter *fmp)
{
time_t now = get_seconds();
time_t ticks = now - fmp->time;
if (ticks == 0)
return;
ticks = min(FM_MAXTICKS, ticks);
while (ticks-- > 0)
fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
fmp->time = now;
fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
fmp->cnt = 0;
}
/* Process any previous ticks, then bump cnt by one (times scale). */
static void fmeter_markevent(struct fmeter *fmp)
{
spin_lock(&fmp->lock);
fmeter_update(fmp);
fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
spin_unlock(&fmp->lock);
}
/* Process any previous ticks, then return current value. */
static int fmeter_getrate(struct fmeter *fmp)
{
int val;
spin_lock(&fmp->lock);
fmeter_update(fmp);
val = fmp->val;
spin_unlock(&fmp->lock);
return val;
}
/*
* Attack task specified by pid in 'pidbuf' to cpuset 'cs', possibly
* writing the path of the old cpuset in 'ppathbuf' if it needs to be
* notified on release.
*
* Call holding manage_sem. May take callback_sem and task_lock of
* the task 'pid' during call.
*/
static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
{
pid_t pid;
struct task_struct *tsk;
struct cpuset *oldcs;
cpumask_t cpus;
nodemask_t from, to;
struct mm_struct *mm;
if (sscanf(pidbuf, "%d", &pid) != 1)
return -EIO;
if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
return -ENOSPC;
if (pid) {
read_lock(&tasklist_lock);
tsk = find_task_by_pid(pid);
if (!tsk || tsk->flags & PF_EXITING) {
read_unlock(&tasklist_lock);
return -ESRCH;
}
get_task_struct(tsk);
read_unlock(&tasklist_lock);
if ((current->euid) && (current->euid != tsk->uid)
&& (current->euid != tsk->suid)) {
put_task_struct(tsk);
return -EACCES;
}
} else {
tsk = current;
get_task_struct(tsk);
}
down(&callback_sem);
task_lock(tsk);
oldcs = tsk->cpuset;
if (!oldcs) {
task_unlock(tsk);
up(&callback_sem);
put_task_struct(tsk);
return -ESRCH;
}
atomic_inc(&cs->count);
rcu_assign_pointer(tsk->cpuset, cs);
task_unlock(tsk);
guarantee_online_cpus(cs, &cpus);
set_cpus_allowed(tsk, cpus);
from = oldcs->mems_allowed;
to = cs->mems_allowed;
up(&callback_sem);
mm = get_task_mm(tsk);
if (mm) {
mpol_rebind_mm(mm, &to);
mmput(mm);
}
if (is_memory_migrate(cs))
do_migrate_pages(tsk->mm, &from, &to, MPOL_MF_MOVE_ALL);
put_task_struct(tsk);
synchronize_rcu();
if (atomic_dec_and_test(&oldcs->count))
check_for_release(oldcs, ppathbuf);
return 0;
}
/* The various types of files and directories in a cpuset file system */
typedef enum {
FILE_ROOT,
FILE_DIR,
FILE_MEMORY_MIGRATE,
FILE_CPULIST,
FILE_MEMLIST,
FILE_CPU_EXCLUSIVE,
FILE_MEM_EXCLUSIVE,
FILE_NOTIFY_ON_RELEASE,
FILE_MEMORY_PRESSURE_ENABLED,
FILE_MEMORY_PRESSURE,
FILE_TASKLIST,
} cpuset_filetype_t;
static ssize_t cpuset_common_file_write(struct file *file, const char __user *userbuf,
size_t nbytes, loff_t *unused_ppos)
{
struct cpuset *cs = __d_cs(file->f_dentry->d_parent);
struct cftype *cft = __d_cft(file->f_dentry);
cpuset_filetype_t type = cft->private;
char *buffer;
char *pathbuf = NULL;
int retval = 0;
/* Crude upper limit on largest legitimate cpulist user might write. */
if (nbytes > 100 + 6 * NR_CPUS)
return -E2BIG;
/* +1 for nul-terminator */
if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
return -ENOMEM;
if (copy_from_user(buffer, userbuf, nbytes)) {
retval = -EFAULT;
goto out1;
}
buffer[nbytes] = 0; /* nul-terminate */
down(&manage_sem);
if (is_removed(cs)) {
retval = -ENODEV;
goto out2;
}
switch (type) {
case FILE_CPULIST:
retval = update_cpumask(cs, buffer);
break;
case FILE_MEMLIST:
retval = update_nodemask(cs, buffer);
break;
case FILE_CPU_EXCLUSIVE:
retval = update_flag(CS_CPU_EXCLUSIVE, cs, buffer);
break;
case FILE_MEM_EXCLUSIVE:
retval = update_flag(CS_MEM_EXCLUSIVE, cs, buffer);
break;
case FILE_NOTIFY_ON_RELEASE:
retval = update_flag(CS_NOTIFY_ON_RELEASE, cs, buffer);
break;
case FILE_MEMORY_MIGRATE:
retval = update_flag(CS_MEMORY_MIGRATE, cs, buffer);
break;
case FILE_MEMORY_PRESSURE_ENABLED:
retval = update_memory_pressure_enabled(cs, buffer);
break;
case FILE_MEMORY_PRESSURE:
retval = -EACCES;
break;
case FILE_TASKLIST:
retval = attach_task(cs, buffer, &pathbuf);
break;
default:
retval = -EINVAL;
goto out2;
}
if (retval == 0)
retval = nbytes;
out2:
up(&manage_sem);
cpuset_release_agent(pathbuf);
out1:
kfree(buffer);
return retval;
}
static ssize_t cpuset_file_write(struct file *file, const char __user *buf,
size_t nbytes, loff_t *ppos)
{
ssize_t retval = 0;
struct cftype *cft = __d_cft(file->f_dentry);
if (!cft)
return -ENODEV;
/* special function ? */
if (cft->write)
retval = cft->write(file, buf, nbytes, ppos);
else
retval = cpuset_common_file_write(file, buf, nbytes, ppos);
return retval;
}
/*
* These ascii lists should be read in a single call, by using a user
* buffer large enough to hold the entire map. If read in smaller
* chunks, there is no guarantee of atomicity. Since the display format
* used, list of ranges of sequential numbers, is variable length,
* and since these maps can change value dynamically, one could read
* gibberish by doing partial reads while a list was changing.
* A single large read to a buffer that crosses a page boundary is
* ok, because the result being copied to user land is not recomputed
* across a page fault.
*/
static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
{
cpumask_t mask;
down(&callback_sem);
mask = cs->cpus_allowed;
up(&callback_sem);
return cpulist_scnprintf(page, PAGE_SIZE, mask);
}
static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
{
nodemask_t mask;
down(&callback_sem);
mask = cs->mems_allowed;
up(&callback_sem);
return nodelist_scnprintf(page, PAGE_SIZE, mask);
}
static ssize_t cpuset_common_file_read(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
struct cftype *cft = __d_cft(file->f_dentry);
struct cpuset *cs = __d_cs(file->f_dentry->d_parent);
cpuset_filetype_t type = cft->private;
char *page;
ssize_t retval = 0;
char *s;
if (!(page = (char *)__get_free_page(GFP_KERNEL)))
return -ENOMEM;
s = page;
switch (type) {
case FILE_CPULIST:
s += cpuset_sprintf_cpulist(s, cs);
break;
case FILE_MEMLIST:
s += cpuset_sprintf_memlist(s, cs);
break;
case FILE_CPU_EXCLUSIVE:
*s++ = is_cpu_exclusive(cs) ? '1' : '0';
break;
case FILE_MEM_EXCLUSIVE:
*s++ = is_mem_exclusive(cs) ? '1' : '0';
break;
case FILE_NOTIFY_ON_RELEASE:
*s++ = notify_on_release(cs) ? '1' : '0';
break;
case FILE_MEMORY_MIGRATE:
*s++ = is_memory_migrate(cs) ? '1' : '0';
break;
case FILE_MEMORY_PRESSURE_ENABLED:
*s++ = cpuset_memory_pressure_enabled ? '1' : '0';
break;
case FILE_MEMORY_PRESSURE:
s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter));
break;
default:
retval = -EINVAL;
goto out;
}
*s++ = '\n';
retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
out:
free_page((unsigned long)page);
return retval;
}
static ssize_t cpuset_file_read(struct file *file, char __user *buf, size_t nbytes,
loff_t *ppos)
{
ssize_t retval = 0;
struct cftype *cft = __d_cft(file->f_dentry);
if (!cft)
return -ENODEV;
/* special function ? */
if (cft->read)
retval = cft->read(file, buf, nbytes, ppos);
else
retval = cpuset_common_file_read(file, buf, nbytes, ppos);
return retval;
}
static int cpuset_file_open(struct inode *inode, struct file *file)
{
int err;
struct cftype *cft;
err = generic_file_open(inode, file);
if (err)
return err;
cft = __d_cft(file->f_dentry);
if (!cft)
return -ENODEV;
if (cft->open)
err = cft->open(inode, file);
else
err = 0;
return err;
}
static int cpuset_file_release(struct inode *inode, struct file *file)
{
struct cftype *cft = __d_cft(file->f_dentry);
if (cft->release)
return cft->release(inode, file);
return 0;
}
/*
* cpuset_rename - Only allow simple rename of directories in place.
*/
static int cpuset_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
if (!S_ISDIR(old_dentry->d_inode->i_mode))
return -ENOTDIR;
if (new_dentry->d_inode)
return -EEXIST;
if (old_dir != new_dir)
return -EIO;
return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
}
static struct file_operations cpuset_file_operations = {
.read = cpuset_file_read,
.write = cpuset_file_write,
.llseek = generic_file_llseek,
.open = cpuset_file_open,
.release = cpuset_file_release,
};
static struct inode_operations cpuset_dir_inode_operations = {
.lookup = simple_lookup,
.mkdir = cpuset_mkdir,
.rmdir = cpuset_rmdir,
.rename = cpuset_rename,
};
static int cpuset_create_file(struct dentry *dentry, int mode)
{
struct inode *inode;
if (!dentry)
return -ENOENT;
if (dentry->d_inode)
return -EEXIST;
inode = cpuset_new_inode(mode);
if (!inode)
return -ENOMEM;
if (S_ISDIR(mode)) {
inode->i_op = &cpuset_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* start off with i_nlink == 2 (for "." entry) */
inode->i_nlink++;
} else if (S_ISREG(mode)) {
inode->i_size = 0;
inode->i_fop = &cpuset_file_operations;
}
d_instantiate(dentry, inode);
dget(dentry); /* Extra count - pin the dentry in core */
return 0;
}
/*
* cpuset_create_dir - create a directory for an object.
* cs: the cpuset we create the directory for.
* It must have a valid ->parent field
* And we are going to fill its ->dentry field.
* name: The name to give to the cpuset directory. Will be copied.
* mode: mode to set on new directory.
*/
static int cpuset_create_dir(struct cpuset *cs, const char *name, int mode)
{
struct dentry *dentry = NULL;
struct dentry *parent;
int error = 0;
parent = cs->parent->dentry;
dentry = cpuset_get_dentry(parent, name);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
error = cpuset_create_file(dentry, S_IFDIR | mode);
if (!error) {
dentry->d_fsdata = cs;
parent->d_inode->i_nlink++;
cs->dentry = dentry;
}
dput(dentry);
return error;
}
static int cpuset_add_file(struct dentry *dir, const struct cftype *cft)
{
struct dentry *dentry;
int error;
down(&dir->d_inode->i_sem);
dentry = cpuset_get_dentry(dir, cft->name);
if (!IS_ERR(dentry)) {
error = cpuset_create_file(dentry, 0644 | S_IFREG);
if (!error)
dentry->d_fsdata = (void *)cft;
dput(dentry);
} else
error = PTR_ERR(dentry);
up(&dir->d_inode->i_sem);
return error;
}
/*
* Stuff for reading the 'tasks' file.
*
* Reading this file can return large amounts of data if a cpuset has
* *lots* of attached tasks. So it may need several calls to read(),
* but we cannot guarantee that the information we produce is correct
* unless we produce it entirely atomically.
*
* Upon tasks file open(), a struct ctr_struct is allocated, that
* will have a pointer to an array (also allocated here). The struct
* ctr_struct * is stored in file->private_data. Its resources will
* be freed by release() when the file is closed. The array is used
* to sprintf the PIDs and then used by read().
*/
/* cpusets_tasks_read array */
struct ctr_struct {
char *buf;
int bufsz;
};
/*
* Load into 'pidarray' up to 'npids' of the tasks using cpuset 'cs'.
* Return actual number of pids loaded. No need to task_lock(p)
* when reading out p->cpuset, as we don't really care if it changes
* on the next cycle, and we are not going to try to dereference it.
*/
static inline int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs)
{
int n = 0;
struct task_struct *g, *p;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (p->cpuset == cs) {
pidarray[n++] = p->pid;
if (unlikely(n == npids))
goto array_full;
}
} while_each_thread(g, p);
array_full:
read_unlock(&tasklist_lock);
return n;
}
static int cmppid(const void *a, const void *b)
{
return *(pid_t *)a - *(pid_t *)b;
}
/*
* Convert array 'a' of 'npids' pid_t's to a string of newline separated
* decimal pids in 'buf'. Don't write more than 'sz' chars, but return
* count 'cnt' of how many chars would be written if buf were large enough.
*/
static int pid_array_to_buf(char *buf, int sz, pid_t *a, int npids)
{
int cnt = 0;
int i;
for (i = 0; i < npids; i++)
cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]);
return cnt;
}
/*
* Handle an open on 'tasks' file. Prepare a buffer listing the
* process id's of tasks currently attached to the cpuset being opened.
*
* Does not require any specific cpuset semaphores, and does not take any.
*/
static int cpuset_tasks_open(struct inode *unused, struct file *file)
{
struct cpuset *cs = __d_cs(file->f_dentry->d_parent);
struct ctr_struct *ctr;
pid_t *pidarray;
int npids;
char c;
if (!(file->f_mode & FMODE_READ))
return 0;
ctr = kmalloc(sizeof(*ctr), GFP_KERNEL);
if (!ctr)
goto err0;
/*
* If cpuset gets more users after we read count, we won't have
* enough space - tough. This race is indistinguishable to the
* caller from the case that the additional cpuset users didn't
* show up until sometime later on.
*/
npids = atomic_read(&cs->count);
pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL);
if (!pidarray)
goto err1;
npids = pid_array_load(pidarray, npids, cs);
sort(pidarray, npids, sizeof(pid_t), cmppid, NULL);
/* Call pid_array_to_buf() twice, first just to get bufsz */
ctr->bufsz = pid_array_to_buf(&c, sizeof(c), pidarray, npids) + 1;
ctr->buf = kmalloc(ctr->bufsz, GFP_KERNEL);
if (!ctr->buf)
goto err2;
ctr->bufsz = pid_array_to_buf(ctr->buf, ctr->bufsz, pidarray, npids);
kfree(pidarray);
file->private_data = ctr;
return 0;
err2:
kfree(pidarray);
err1:
kfree(ctr);
err0:
return -ENOMEM;
}
static ssize_t cpuset_tasks_read(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
struct ctr_struct *ctr = file->private_data;
if (*ppos + nbytes > ctr->bufsz)
nbytes = ctr->bufsz - *ppos;
if (copy_to_user(buf, ctr->buf + *ppos, nbytes))
return -EFAULT;
*ppos += nbytes;
return nbytes;
}
static int cpuset_tasks_release(struct inode *unused_inode, struct file *file)
{
struct ctr_struct *ctr;
if (file->f_mode & FMODE_READ) {
ctr = file->private_data;
kfree(ctr->buf);
kfree(ctr);
}
return 0;
}
/*
* for the common functions, 'private' gives the type of file
*/
static struct cftype cft_tasks = {
.name = "tasks",
.open = cpuset_tasks_open,
.read = cpuset_tasks_read,
.release = cpuset_tasks_release,
.private = FILE_TASKLIST,
};
static struct cftype cft_cpus = {
.name = "cpus",
.private = FILE_CPULIST,
};
static struct cftype cft_mems = {
.name = "mems",
.private = FILE_MEMLIST,
};
static struct cftype cft_cpu_exclusive = {
.name = "cpu_exclusive",
.private = FILE_CPU_EXCLUSIVE,
};
static struct cftype cft_mem_exclusive = {
.name = "mem_exclusive",
.private = FILE_MEM_EXCLUSIVE,
};
static struct cftype cft_notify_on_release = {
.name = "notify_on_release",
.private = FILE_NOTIFY_ON_RELEASE,
};
static struct cftype cft_memory_migrate = {
.name = "memory_migrate",
.private = FILE_MEMORY_MIGRATE,
};
static struct cftype cft_memory_pressure_enabled = {
.name = "memory_pressure_enabled",
.private = FILE_MEMORY_PRESSURE_ENABLED,
};
static struct cftype cft_memory_pressure = {
.name = "memory_pressure",
.private = FILE_MEMORY_PRESSURE,
};
static int cpuset_populate_dir(struct dentry *cs_dentry)
{
int err;
if ((err = cpuset_add_file(cs_dentry, &cft_cpus)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_mems)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_cpu_exclusive)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_mem_exclusive)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_notify_on_release)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_memory_migrate)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_memory_pressure)) < 0)
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0)
return err;
return 0;
}
/*
* cpuset_create - create a cpuset
* parent: cpuset that will be parent of the new cpuset.
* name: name of the new cpuset. Will be strcpy'ed.
* mode: mode to set on new inode
*
* Must be called with the semaphore on the parent inode held
*/
static long cpuset_create(struct cpuset *parent, const char *name, int mode)
{
struct cpuset *cs;
int err;
cs = kmalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return -ENOMEM;
down(&manage_sem);
cpuset_update_task_memory_state();
cs->flags = 0;
if (notify_on_release(parent))
set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags);
cs->cpus_allowed = CPU_MASK_NONE;
cs->mems_allowed = NODE_MASK_NONE;
atomic_set(&cs->count, 0);
INIT_LIST_HEAD(&cs->sibling);
INIT_LIST_HEAD(&cs->children);
atomic_inc(&cpuset_mems_generation);
cs->mems_generation = atomic_read(&cpuset_mems_generation);
fmeter_init(&cs->fmeter);
cs->parent = parent;
down(&callback_sem);
list_add(&cs->sibling, &cs->parent->children);
number_of_cpusets++;
up(&callback_sem);
err = cpuset_create_dir(cs, name, mode);
if (err < 0)
goto err;
/*
* Release manage_sem before cpuset_populate_dir() because it
* will down() this new directory's i_sem and if we race with
* another mkdir, we might deadlock.
*/
up(&manage_sem);
err = cpuset_populate_dir(cs->dentry);
/* If err < 0, we have a half-filled directory - oh well ;) */
return 0;
err:
list_del(&cs->sibling);
up(&manage_sem);
kfree(cs);
return err;
}
static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
struct cpuset *c_parent = dentry->d_parent->d_fsdata;
/* the vfs holds inode->i_sem already */
return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR);
}
static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
{
struct cpuset *cs = dentry->d_fsdata;
struct dentry *d;
struct cpuset *parent;
char *pathbuf = NULL;
/* the vfs holds both inode->i_sem already */
down(&manage_sem);
cpuset_update_task_memory_state();
if (atomic_read(&cs->count) > 0) {
up(&manage_sem);
return -EBUSY;
}
if (!list_empty(&cs->children)) {
up(&manage_sem);
return -EBUSY;
}
parent = cs->parent;
down(&callback_sem);
set_bit(CS_REMOVED, &cs->flags);
if (is_cpu_exclusive(cs))
update_cpu_domains(cs);
list_del(&cs->sibling); /* delete my sibling from parent->children */
spin_lock(&cs->dentry->d_lock);
d = dget(cs->dentry);
cs->dentry = NULL;
spin_unlock(&d->d_lock);
cpuset_d_remove_dir(d);
dput(d);
number_of_cpusets--;
up(&callback_sem);
if (list_empty(&parent->children))
check_for_release(parent, &pathbuf);
up(&manage_sem);
cpuset_release_agent(pathbuf);
return 0;
}
/*
* cpuset_init_early - just enough so that the calls to
* cpuset_update_task_memory_state() in early init code
* are harmless.
*/
int __init cpuset_init_early(void)
{
struct task_struct *tsk = current;
tsk->cpuset = &top_cpuset;
tsk->cpuset->mems_generation = atomic_read(&cpuset_mems_generation);
return 0;
}
/**
* cpuset_init - initialize cpusets at system boot
*
* Description: Initialize top_cpuset and the cpuset internal file system,
**/
int __init cpuset_init(void)
{
struct dentry *root;
int err;
top_cpuset.cpus_allowed = CPU_MASK_ALL;
top_cpuset.mems_allowed = NODE_MASK_ALL;
fmeter_init(&top_cpuset.fmeter);
atomic_inc(&cpuset_mems_generation);
top_cpuset.mems_generation = atomic_read(&cpuset_mems_generation);
init_task.cpuset = &top_cpuset;
err = register_filesystem(&cpuset_fs_type);
if (err < 0)
goto out;
cpuset_mount = kern_mount(&cpuset_fs_type);
if (IS_ERR(cpuset_mount)) {
printk(KERN_ERR "cpuset: could not mount!\n");
err = PTR_ERR(cpuset_mount);
cpuset_mount = NULL;
goto out;
}
root = cpuset_mount->mnt_sb->s_root;
root->d_fsdata = &top_cpuset;
root->d_inode->i_nlink++;
top_cpuset.dentry = root;
root->d_inode->i_op = &cpuset_dir_inode_operations;
number_of_cpusets = 1;
err = cpuset_populate_dir(root);
/* memory_pressure_enabled is in root cpuset only */
if (err == 0)
err = cpuset_add_file(root, &cft_memory_pressure_enabled);
out:
return err;
}
/**
* cpuset_init_smp - initialize cpus_allowed
*
* Description: Finish top cpuset after cpu, node maps are initialized
**/
void __init cpuset_init_smp(void)
{
top_cpuset.cpus_allowed = cpu_online_map;
top_cpuset.mems_allowed = node_online_map;
}
/**
* cpuset_fork - attach newly forked task to its parents cpuset.
* @tsk: pointer to task_struct of forking parent process.
*
* Description: A task inherits its parent's cpuset at fork().
*
* A pointer to the shared cpuset was automatically copied in fork.c
* by dup_task_struct(). However, we ignore that copy, since it was
* not made under the protection of task_lock(), so might no longer be
* a valid cpuset pointer. attach_task() might have already changed
* current->cpuset, allowing the previously referenced cpuset to
* be removed and freed. Instead, we task_lock(current) and copy
* its present value of current->cpuset for our freshly forked child.
*
* At the point that cpuset_fork() is called, 'current' is the parent
* task, and the passed argument 'child' points to the child task.
**/
void cpuset_fork(struct task_struct *child)
{
task_lock(current);
child->cpuset = current->cpuset;
atomic_inc(&child->cpuset->count);
task_unlock(current);
}
/**
* cpuset_exit - detach cpuset from exiting task
* @tsk: pointer to task_struct of exiting process
*
* Description: Detach cpuset from @tsk and release it.
*
* Note that cpusets marked notify_on_release force every task in
* them to take the global manage_sem semaphore when exiting.
* This could impact scaling on very large systems. Be reluctant to
* use notify_on_release cpusets where very high task exit scaling
* is required on large systems.
*
* Don't even think about derefencing 'cs' after the cpuset use count
* goes to zero, except inside a critical section guarded by manage_sem
* or callback_sem. Otherwise a zero cpuset use count is a license to
* any other task to nuke the cpuset immediately, via cpuset_rmdir().
*
* This routine has to take manage_sem, not callback_sem, because
* it is holding that semaphore while calling check_for_release(),
* which calls kmalloc(), so can't be called holding callback__sem().
*
* We don't need to task_lock() this reference to tsk->cpuset,
* because tsk is already marked PF_EXITING, so attach_task() won't
* mess with it, or task is a failed fork, never visible to attach_task.
**/
void cpuset_exit(struct task_struct *tsk)
{
struct cpuset *cs;
cs = tsk->cpuset;
tsk->cpuset = NULL;
if (notify_on_release(cs)) {
char *pathbuf = NULL;
down(&manage_sem);
if (atomic_dec_and_test(&cs->count))
check_for_release(cs, &pathbuf);
up(&manage_sem);
cpuset_release_agent(pathbuf);
} else {
atomic_dec(&cs->count);
}
}
/**
* cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
* @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
*
* Description: Returns the cpumask_t cpus_allowed of the cpuset
* attached to the specified @tsk. Guaranteed to return some non-empty
* subset of cpu_online_map, even if this means going outside the
* tasks cpuset.
**/
cpumask_t cpuset_cpus_allowed(struct task_struct *tsk)
{
cpumask_t mask;
down(&callback_sem);
task_lock(tsk);
guarantee_online_cpus(tsk->cpuset, &mask);
task_unlock(tsk);
up(&callback_sem);
return mask;
}
void cpuset_init_current_mems_allowed(void)
{
current->mems_allowed = NODE_MASK_ALL;
}
/**
* cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
* @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
*
* Description: Returns the nodemask_t mems_allowed of the cpuset
* attached to the specified @tsk. Guaranteed to return some non-empty
* subset of node_online_map, even if this means going outside the
* tasks cpuset.
**/
nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
nodemask_t mask;
down(&callback_sem);
task_lock(tsk);
guarantee_online_mems(tsk->cpuset, &mask);
task_unlock(tsk);
up(&callback_sem);
return mask;
}
/**
* cpuset_zonelist_valid_mems_allowed - check zonelist vs. curremt mems_allowed
* @zl: the zonelist to be checked
*
* Are any of the nodes on zonelist zl allowed in current->mems_allowed?
*/
int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl)
{
int i;
for (i = 0; zl->zones[i]; i++) {
int nid = zl->zones[i]->zone_pgdat->node_id;
if (node_isset(nid, current->mems_allowed))
return 1;
}
return 0;
}
/*
* nearest_exclusive_ancestor() - Returns the nearest mem_exclusive
* ancestor to the specified cpuset. Call holding callback_sem.
* If no ancestor is mem_exclusive (an unusual configuration), then
* returns the root cpuset.
*/
static const struct cpuset *nearest_exclusive_ancestor(const struct cpuset *cs)
{
while (!is_mem_exclusive(cs) && cs->parent)
cs = cs->parent;
return cs;
}
/**
* cpuset_zone_allowed - Can we allocate memory on zone z's memory node?
* @z: is this zone on an allowed node?
* @gfp_mask: memory allocation flags (we use __GFP_HARDWALL)
*
* If we're in interrupt, yes, we can always allocate. If zone
* z's node is in our tasks mems_allowed, yes. If it's not a
* __GFP_HARDWALL request and this zone's nodes is in the nearest
* mem_exclusive cpuset ancestor to this tasks cpuset, yes.
* Otherwise, no.
*
* GFP_USER allocations are marked with the __GFP_HARDWALL bit,
* and do not allow allocations outside the current tasks cpuset.
* GFP_KERNEL allocations are not so marked, so can escape to the
* nearest mem_exclusive ancestor cpuset.
*
* Scanning up parent cpusets requires callback_sem. The __alloc_pages()
* routine only calls here with __GFP_HARDWALL bit _not_ set if
* it's a GFP_KERNEL allocation, and all nodes in the current tasks
* mems_allowed came up empty on the first pass over the zonelist.
* So only GFP_KERNEL allocations, if all nodes in the cpuset are
* short of memory, might require taking the callback_sem semaphore.
*
* The first loop over the zonelist in mm/page_alloc.c:__alloc_pages()
* calls here with __GFP_HARDWALL always set in gfp_mask, enforcing
* hardwall cpusets - no allocation on a node outside the cpuset is
* allowed (unless in interrupt, of course).
*
* The second loop doesn't even call here for GFP_ATOMIC requests
* (if the __alloc_pages() local variable 'wait' is set). That check
* and the checks below have the combined affect in the second loop of
* the __alloc_pages() routine that:
* in_interrupt - any node ok (current task context irrelevant)
* GFP_ATOMIC - any node ok
* GFP_KERNEL - any node in enclosing mem_exclusive cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
**/
int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
{
int node; /* node that zone z is on */
const struct cpuset *cs; /* current cpuset ancestors */
int allowed = 1; /* is allocation in zone z allowed? */
if (in_interrupt())
return 1;
node = z->zone_pgdat->node_id;
if (node_isset(node, current->mems_allowed))
return 1;
if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
return 0;
if (current->flags & PF_EXITING) /* Let dying task have memory */
return 1;
/* Not hardwall and node outside mems_allowed: scan up cpusets */
down(&callback_sem);
task_lock(current);
cs = nearest_exclusive_ancestor(current->cpuset);
task_unlock(current);
allowed = node_isset(node, cs->mems_allowed);
up(&callback_sem);
return allowed;
}
/**
* cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors?
* @p: pointer to task_struct of some other task.
*
* Description: Return true if the nearest mem_exclusive ancestor
* cpusets of tasks @p and current overlap. Used by oom killer to
* determine if task @p's memory usage might impact the memory
* available to the current task.
*
* Acquires callback_sem - not suitable for calling from a fast path.
**/
int cpuset_excl_nodes_overlap(const struct task_struct *p)
{
const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */
int overlap = 0; /* do cpusets overlap? */
down(&callback_sem);
task_lock(current);
if (current->flags & PF_EXITING) {
task_unlock(current);
goto done;
}
cs1 = nearest_exclusive_ancestor(current->cpuset);
task_unlock(current);
task_lock((struct task_struct *)p);
if (p->flags & PF_EXITING) {
task_unlock((struct task_struct *)p);
goto done;
}
cs2 = nearest_exclusive_ancestor(p->cpuset);
task_unlock((struct task_struct *)p);
overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed);
done:
up(&callback_sem);
return overlap;
}
/*
* Collection of memory_pressure is suppressed unless
* this flag is enabled by writing "1" to the special
* cpuset file 'memory_pressure_enabled' in the root cpuset.
*/
int cpuset_memory_pressure_enabled __read_mostly;
/**
* cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
*
* Keep a running average of the rate of synchronous (direct)
* page reclaim efforts initiated by tasks in each cpuset.
*
* This represents the rate at which some task in the cpuset
* ran low on memory on all nodes it was allowed to use, and
* had to enter the kernels page reclaim code in an effort to
* create more free memory by tossing clean pages or swapping
* or writing dirty pages.
*
* Display to user space in the per-cpuset read-only file
* "memory_pressure". Value displayed is an integer
* representing the recent rate of entry into the synchronous
* (direct) page reclaim by any task attached to the cpuset.
**/
void __cpuset_memory_pressure_bump(void)
{
struct cpuset *cs;
task_lock(current);
cs = current->cpuset;
fmeter_markevent(&cs->fmeter);
task_unlock(current);
}
/*
* proc_cpuset_show()
* - Print tasks cpuset path into seq_file.
* - Used for /proc/<pid>/cpuset.
* - No need to task_lock(tsk) on this tsk->cpuset reference, as it
* doesn't really matter if tsk->cpuset changes after we read it,
* and we take manage_sem, keeping attach_task() from changing it
* anyway.
*/
static int proc_cpuset_show(struct seq_file *m, void *v)
{
struct cpuset *cs;
struct task_struct *tsk;
char *buf;
int retval = 0;
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!buf)
return -ENOMEM;
tsk = m->private;
down(&manage_sem);
cs = tsk->cpuset;
if (!cs) {
retval = -EINVAL;
goto out;
}
retval = cpuset_path(cs, buf, PAGE_SIZE);
if (retval < 0)
goto out;
seq_puts(m, buf);
seq_putc(m, '\n');
out:
up(&manage_sem);
kfree(buf);
return retval;
}
static int cpuset_open(struct inode *inode, struct file *file)
{
struct task_struct *tsk = PROC_I(inode)->task;
return single_open(file, proc_cpuset_show, tsk);
}
struct file_operations proc_cpuset_operations = {
.open = cpuset_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
char *cpuset_task_status_allowed(struct task_struct *task, char *buffer)
{
buffer += sprintf(buffer, "Cpus_allowed:\t");
buffer += cpumask_scnprintf(buffer, PAGE_SIZE, task->cpus_allowed);
buffer += sprintf(buffer, "\n");
buffer += sprintf(buffer, "Mems_allowed:\t");
buffer += nodemask_scnprintf(buffer, PAGE_SIZE, task->mems_allowed);
buffer += sprintf(buffer, "\n");
return buffer;
}