* Processor and Memory placement constraints for sets of tasks.
*
* Copyright (C) 2003 BULL SA.
- * Copyright (C) 2004 Silicon Graphics, Inc.
+ * Copyright (C) 2004-2006 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>
+ * 2003-10-10 Written by Simon Derr.
* 2003-10-22 Updates by Stephen Hemminger.
- * 2004 May-July Rework by Paul Jackson <pj@sgi.com>
+ * 2004 May-July Rework by Paul Jackson.
*
* 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
#include <asm/uaccess.h>
#include <asm/atomic.h>
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
#define CPUSET_SUPER_MAGIC 0x27e0eb
CS_MEM_EXCLUSIVE,
CS_MEMORY_MIGRATE,
CS_REMOVED,
- CS_NOTIFY_ON_RELEASE
+ CS_NOTIFY_ON_RELEASE,
+ CS_SPREAD_PAGE,
+ CS_SPREAD_SLAB,
} 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);
+ 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);
+ return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
}
static inline int is_removed(const struct cpuset *cs)
{
- return !!test_bit(CS_REMOVED, &cs->flags);
+ 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);
+ 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);
+ return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
+}
+
+static inline int is_spread_page(const struct cpuset *cs)
+{
+ return test_bit(CS_SPREAD_PAGE, &cs->flags);
+}
+
+static inline int is_spread_slab(const struct cpuset *cs)
+{
+ return test_bit(CS_SPREAD_SLAB, &cs->flags);
}
/*
- * Increment this atomic integer everytime any cpuset changes its
+ * Increment this 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.
* 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.
+ *
+ * Since cpuset_mems_generation is guarded by manage_mutex,
+ * there is no need to mark it atomic.
*/
-static atomic_t cpuset_mems_generation = ATOMIC_INIT(1);
+static int cpuset_mems_generation;
static struct cpuset top_cpuset = {
.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
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
+ * We have two global cpuset mutexes below. They can nest.
+ * It is ok to first take manage_mutex, then nest callback_mutex. 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
+ * A task must hold both mutexes to modify cpusets. If a task
+ * holds manage_mutex, then it blocks others wanting that mutex,
+ * ensuring that it is the only task able to also acquire callback_mutex
* 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
+ * also allocate memory while just holding manage_mutex. 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.
+ * acquire callback_mutex to query cpusets. Once it is ready to make
+ * the changes, it takes callback_mutex, 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
+ * callback_mutex, as that would risk double tripping on callback_mutex
* 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
+ * If a task is only holding callback_mutex, 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
+ * So in general, code holding manage_mutex or callback_mutex 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
+ * zero, then only attach_task(), which holds both mutexes, 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
+ * So code holding manage_mutex or callback_mutex 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
+ * holds manage_mutex or callback_mutex 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.
+ * both of those mutexes.
*
* The cpuset_common_file_write handler for operations that modify
- * the cpuset hierarchy holds manage_sem across the entire operation,
+ * the cpuset hierarchy holds manage_mutex across the entire operation,
* single threading all such cpuset modifications across the system.
*
- * The cpuset_common_file_read() handlers only hold callback_sem across
+ * The cpuset_common_file_read() handlers only hold callback_mutex 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
+ * (usually) take either mutex. 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
+ * when a task in a notify_on_release cpuset exits. Then manage_mutex
* 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.
*
* 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
+ * so using both mutexes, 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
+ * expense of grabbing a system global mutex. 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
* the routine cpuset_update_task_memory_state().
*/
-static DECLARE_MUTEX(manage_sem);
-static DECLARE_MUTEX(callback_sem);
+static DEFINE_MUTEX(manage_mutex);
+static DEFINE_MUTEX(callback_mutex);
/*
* A couple of forward declarations required, due to cyclic reference loop:
}
/*
- * Call with manage_sem held. Writes path of cpuset into buf.
+ * Call with manage_mutex held. Writes path of cpuset into buf.
* Returns 0 on success, -errno on error.
*/
* 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
+ * When we had only one cpuset mutex, 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.
+ * holding manage_mutex, but we still don't, so as to minimize
+ * the time manage_mutex is held.
*/
static void cpuset_release_agent(const char *pathbuf)
* 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.
+ * cpuset_release_agent() with it later on, once manage_mutex is dropped.
+ * Call here with manage_mutex 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
+ * calling check_for_release() with manage_mutex held and the address
+ * of the pathbuf pointer, then dropping manage_mutex, then calling
* cpuset_release_agent() with pathbuf, as set by check_for_release().
*/
* One way or another, we guarantee to return some non-empty subset
* of cpu_online_map.
*
- * Call with callback_sem held.
+ * Call with callback_mutex held.
*/
static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask)
* One way or another, we guarantee to return some non-empty subset
* of node_online_map.
*
- * Call with callback_sem held.
+ * Call with callback_mutex held.
*/
static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
* 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
+ * Call without callback_mutex or task_lock() held. May be
+ * called with or without manage_mutex held. Thanks in part to
+ * 'the_top_cpuset_hack', the tasks cpuset pointer will never
+ * be NULL. This routine also might acquire callback_mutex and
* current->mm->mmap_sem during call.
*
* Reading current->cpuset->mems_generation doesn't need task_lock
}
if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
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;
+ if (is_spread_page(cs))
+ tsk->flags |= PF_SPREAD_PAGE;
+ else
+ tsk->flags &= ~PF_SPREAD_PAGE;
+ if (is_spread_slab(cs))
+ tsk->flags |= PF_SPREAD_SLAB;
+ else
+ tsk->flags &= ~PF_SPREAD_SLAB;
task_unlock(tsk);
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
mpol_rebind_task(tsk, &tsk->mems_allowed);
}
}
*
* 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.
+ * are only set if the other's are set. Call holding manage_mutex.
*/
static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
* 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.
+ * manage_mutex held.
*
* 'cur' is the address of an actual, in-use cpuset. Operations
* such as list traversal that depend on the actual address of the
* exclusive child cpusets
* Build these two partitions by calling partition_sched_domains
*
- * Call with manage_sem held. May nest a call to the
+ * Call with manage_mutex held. May nest a call to the
* lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
*/
}
/*
- * Call with manage_sem held. May take callback_sem during call.
+ * Call with manage_mutex held. May take callback_mutex during call.
*/
static int update_cpumask(struct cpuset *cs, char *buf)
if (retval < 0)
return retval;
cpus_unchanged = cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed);
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
cs->cpus_allowed = trialcs.cpus_allowed;
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
if (is_cpu_exclusive(cs) && !cpus_unchanged)
update_cpu_domains(cs);
return 0;
}
+/*
+ * cpuset_migrate_mm
+ *
+ * Migrate memory region from one set of nodes to another.
+ *
+ * Temporarilly set tasks mems_allowed to target nodes of migration,
+ * so that the migration code can allocate pages on these nodes.
+ *
+ * Call holding manage_mutex, so our current->cpuset won't change
+ * during this call, as manage_mutex holds off any attach_task()
+ * calls. Therefore we don't need to take task_lock around the
+ * call to guarantee_online_mems(), as we know no one is changing
+ * our tasks cpuset.
+ *
+ * Hold callback_mutex around the two modifications of our tasks
+ * mems_allowed to synchronize with cpuset_mems_allowed().
+ *
+ * While the mm_struct we are migrating is typically from some
+ * other task, the task_struct mems_allowed that we are hacking
+ * is for our current task, which must allocate new pages for that
+ * migrating memory region.
+ *
+ * We call cpuset_update_task_memory_state() before hacking
+ * our tasks mems_allowed, so that we are assured of being in
+ * sync with our tasks cpuset, and in particular, callbacks to
+ * cpuset_update_task_memory_state() from nested page allocations
+ * won't see any mismatch of our cpuset and task mems_generation
+ * values, so won't overwrite our hacked tasks mems_allowed
+ * nodemask.
+ */
+
+static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
+ const nodemask_t *to)
+{
+ struct task_struct *tsk = current;
+
+ cpuset_update_task_memory_state();
+
+ mutex_lock(&callback_mutex);
+ tsk->mems_allowed = *to;
+ mutex_unlock(&callback_mutex);
+
+ do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
+
+ mutex_lock(&callback_mutex);
+ guarantee_online_mems(tsk->cpuset, &tsk->mems_allowed);
+ mutex_unlock(&callback_mutex);
+}
+
/*
* Handle user request to change the 'mems' memory placement
* of a cpuset. Needs to validate the request, update the
* 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.
+ * Call with manage_mutex held. May take callback_mutex 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.
if (retval < 0)
goto done;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
cs->mems_allowed = trialcs.mems_allowed;
- atomic_inc(&cpuset_mems_generation);
- cs->mems_generation = atomic_read(&cpuset_mems_generation);
- up(&callback_sem);
+ cs->mems_generation = cpuset_mems_generation++;
+ mutex_unlock(&callback_mutex);
set_cpuset_being_rebound(cs); /* causes mpol_copy() rebind */
* 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
+ * cpuset manage_mutex, 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.
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);
- }
+ if (migrate)
+ cpuset_migrate_mm(mm, &oldmem, &cs->mems_allowed);
mmput(mm);
}
}
/*
- * Call with manage_sem held.
+ * Call with manage_mutex held.
*/
static int update_memory_pressure_enabled(struct cpuset *cs, char *buf)
/*
* 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_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE,
+ * CS_SPREAD_PAGE, CS_SPREAD_SLAB)
* cs: the cpuset to update
* buf: the buffer where we read the 0 or 1
*
- * Call with manage_sem held.
+ * Call with manage_mutex held.
*/
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf)
return err;
cpu_exclusive_changed =
(is_cpu_exclusive(cs) != is_cpu_exclusive(&trialcs));
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
if (turning_on)
set_bit(bit, &cs->flags);
else
clear_bit(bit, &cs->flags);
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
if (cpu_exclusive_changed)
update_cpu_domains(cs);
* 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
+ * Call holding manage_mutex. May take callback_mutex and task_lock of
* the task 'pid' during call.
*/
get_task_struct(tsk);
}
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
task_lock(tsk);
oldcs = tsk->cpuset;
if (!oldcs) {
task_unlock(tsk);
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
put_task_struct(tsk);
return -ESRCH;
}
from = oldcs->mems_allowed;
to = cs->mems_allowed;
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
mm = get_task_mm(tsk);
if (mm) {
mpol_rebind_mm(mm, &to);
+ if (is_memory_migrate(cs))
+ cpuset_migrate_mm(mm, &from, &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))
FILE_NOTIFY_ON_RELEASE,
FILE_MEMORY_PRESSURE_ENABLED,
FILE_MEMORY_PRESSURE,
+ FILE_SPREAD_PAGE,
+ FILE_SPREAD_SLAB,
FILE_TASKLIST,
} cpuset_filetype_t;
}
buffer[nbytes] = 0; /* nul-terminate */
- down(&manage_sem);
+ mutex_lock(&manage_mutex);
if (is_removed(cs)) {
retval = -ENODEV;
case FILE_MEMORY_PRESSURE:
retval = -EACCES;
break;
+ case FILE_SPREAD_PAGE:
+ retval = update_flag(CS_SPREAD_PAGE, cs, buffer);
+ cs->mems_generation = cpuset_mems_generation++;
+ break;
+ case FILE_SPREAD_SLAB:
+ retval = update_flag(CS_SPREAD_SLAB, cs, buffer);
+ cs->mems_generation = cpuset_mems_generation++;
+ break;
case FILE_TASKLIST:
retval = attach_task(cs, buffer, &pathbuf);
break;
if (retval == 0)
retval = nbytes;
out2:
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
cpuset_release_agent(pathbuf);
out1:
kfree(buffer);
{
cpumask_t mask;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
mask = cs->cpus_allowed;
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
return cpulist_scnprintf(page, PAGE_SIZE, mask);
}
{
nodemask_t mask;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
mask = cs->mems_allowed;
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
return nodelist_scnprintf(page, PAGE_SIZE, mask);
}
case FILE_MEMORY_PRESSURE:
s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter));
break;
+ case FILE_SPREAD_PAGE:
+ *s++ = is_spread_page(cs) ? '1' : '0';
+ break;
+ case FILE_SPREAD_SLAB:
+ *s++ = is_spread_slab(cs) ? '1' : '0';
+ break;
default:
retval = -EINVAL;
goto out;
* 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.
+ * Does not require any specific cpuset mutexes, and does not take any.
*/
static int cpuset_tasks_open(struct inode *unused, struct file *file)
{
.private = FILE_MEMORY_PRESSURE,
};
+static struct cftype cft_spread_page = {
+ .name = "memory_spread_page",
+ .private = FILE_SPREAD_PAGE,
+};
+
+static struct cftype cft_spread_slab = {
+ .name = "memory_spread_slab",
+ .private = FILE_SPREAD_SLAB,
+};
+
static int cpuset_populate_dir(struct dentry *cs_dentry)
{
int err;
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_memory_pressure)) < 0)
return err;
+ if ((err = cpuset_add_file(cs_dentry, &cft_spread_page)) < 0)
+ return err;
+ if ((err = cpuset_add_file(cs_dentry, &cft_spread_slab)) < 0)
+ return err;
if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0)
return err;
return 0;
* 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
+ * Must be called with the mutex on the parent inode held
*/
static long cpuset_create(struct cpuset *parent, const char *name, int mode)
if (!cs)
return -ENOMEM;
- down(&manage_sem);
+ mutex_lock(&manage_mutex);
cpuset_update_task_memory_state();
cs->flags = 0;
if (notify_on_release(parent))
set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags);
+ if (is_spread_page(parent))
+ set_bit(CS_SPREAD_PAGE, &cs->flags);
+ if (is_spread_slab(parent))
+ set_bit(CS_SPREAD_SLAB, &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);
+ cs->mems_generation = cpuset_mems_generation++;
fmeter_init(&cs->fmeter);
cs->parent = parent;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
list_add(&cs->sibling, &cs->parent->children);
number_of_cpusets++;
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
err = cpuset_create_dir(cs, name, mode);
if (err < 0)
goto err;
/*
- * Release manage_sem before cpuset_populate_dir() because it
+ * Release manage_mutex before cpuset_populate_dir() because it
* will down() this new directory's i_mutex and if we race with
* another mkdir, we might deadlock.
*/
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
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);
+ mutex_unlock(&manage_mutex);
kfree(cs);
return err;
}
/* the vfs holds both inode->i_mutex already */
- down(&manage_sem);
+ mutex_lock(&manage_mutex);
cpuset_update_task_memory_state();
if (atomic_read(&cs->count) > 0) {
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
return -EBUSY;
}
if (!list_empty(&cs->children)) {
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
return -EBUSY;
}
parent = cs->parent;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
set_bit(CS_REMOVED, &cs->flags);
if (is_cpu_exclusive(cs))
update_cpu_domains(cs);
cpuset_d_remove_dir(d);
dput(d);
number_of_cpusets--;
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
if (list_empty(&parent->children))
check_for_release(parent, &pathbuf);
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
cpuset_release_agent(pathbuf);
return 0;
}
struct task_struct *tsk = current;
tsk->cpuset = &top_cpuset;
- tsk->cpuset->mems_generation = atomic_read(&cpuset_mems_generation);
+ tsk->cpuset->mems_generation = cpuset_mems_generation++;
return 0;
}
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);
+ top_cpuset.mems_generation = cpuset_mems_generation++;
init_task.cpuset = &top_cpuset;
* 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.
+ * them to take the global manage_mutex mutex 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
+ * goes to zero, except inside a critical section guarded by manage_mutex
+ * or callback_mutex. 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().
+ * This routine has to take manage_mutex, not callback_mutex, because
+ * it is holding that mutex while calling check_for_release(),
+ * which calls kmalloc(), so can't be called holding callback_mutex().
*
* 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.
+ *
+ * the_top_cpuset_hack:
+ *
+ * Set the exiting tasks cpuset to the root cpuset (top_cpuset).
+ *
+ * Don't leave a task unable to allocate memory, as that is an
+ * accident waiting to happen should someone add a callout in
+ * do_exit() after the cpuset_exit() call that might allocate.
+ * If a task tries to allocate memory with an invalid cpuset,
+ * it will oops in cpuset_update_task_memory_state().
+ *
+ * We call cpuset_exit() while the task is still competent to
+ * handle notify_on_release(), then leave the task attached to
+ * the root cpuset (top_cpuset) for the remainder of its exit.
+ *
+ * To do this properly, we would increment the reference count on
+ * top_cpuset, and near the very end of the kernel/exit.c do_exit()
+ * code we would add a second cpuset function call, to drop that
+ * reference. This would just create an unnecessary hot spot on
+ * the top_cpuset reference count, to no avail.
+ *
+ * Normally, holding a reference to a cpuset without bumping its
+ * count is unsafe. The cpuset could go away, or someone could
+ * attach us to a different cpuset, decrementing the count on
+ * the first cpuset that we never incremented. But in this case,
+ * top_cpuset isn't going away, and either task has PF_EXITING set,
+ * which wards off any attach_task() attempts, or task is a failed
+ * fork, never visible to attach_task.
+ *
+ * Another way to do this would be to set the cpuset pointer
+ * to NULL here, and check in cpuset_update_task_memory_state()
+ * for a NULL pointer. This hack avoids that NULL check, for no
+ * cost (other than this way too long comment ;).
**/
void cpuset_exit(struct task_struct *tsk)
struct cpuset *cs;
cs = tsk->cpuset;
- tsk->cpuset = NULL;
+ tsk->cpuset = &top_cpuset; /* the_top_cpuset_hack - see above */
if (notify_on_release(cs)) {
char *pathbuf = NULL;
- down(&manage_sem);
+ mutex_lock(&manage_mutex);
if (atomic_dec_and_test(&cs->count))
check_for_release(cs, &pathbuf);
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
cpuset_release_agent(pathbuf);
} else {
atomic_dec(&cs->count);
{
cpumask_t mask;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
task_lock(tsk);
guarantee_online_cpus(tsk->cpuset, &mask);
task_unlock(tsk);
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
return mask;
}
{
nodemask_t mask;
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
task_lock(tsk);
guarantee_online_mems(tsk->cpuset, &mask);
task_unlock(tsk);
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
return mask;
}
/*
* nearest_exclusive_ancestor() - Returns the nearest mem_exclusive
- * ancestor to the specified cpuset. Call holding callback_sem.
+ * ancestor to the specified cpuset. Call holding callback_mutex.
* If no ancestor is mem_exclusive (an unusual configuration), then
* returns the root 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()
+ * Scanning up parent cpusets requires callback_mutex. 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:
+ * short of memory, might require taking the callback_mutex mutex.
+ *
+ * The first call here from mm/page_alloc:get_page_from_freelist()
+ * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets, so
+ * no allocation on a node outside the cpuset is allowed (unless in
+ * interrupt, of course).
+ *
+ * The second pass through get_page_from_freelist() doesn't even call
+ * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
+ * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
+ * in alloc_flags. That logic and the checks below have the combined
+ * affect 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.
+ *
+ * Rule:
+ * Don't call cpuset_zone_allowed() if you can't sleep, unless you
+ * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
+ * the code that might scan up ancestor cpusets and sleep.
**/
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? */
+ int allowed; /* is allocation in zone z allowed? */
if (in_interrupt())
return 1;
node = z->zone_pgdat->node_id;
+ might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
if (node_isset(node, current->mems_allowed))
return 1;
if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
return 1;
/* Not hardwall and node outside mems_allowed: scan up cpusets */
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
task_lock(current);
cs = nearest_exclusive_ancestor(current->cpuset);
task_unlock(current);
allowed = node_isset(node, cs->mems_allowed);
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
return allowed;
}
/**
* cpuset_lock - lock out any changes to cpuset structures
*
- * The out of memory (oom) code needs to lock down cpusets
+ * The out of memory (oom) code needs to mutex_lock cpusets
* from being changed while it scans the tasklist looking for a
- * task in an overlapping cpuset. Expose callback_sem via this
+ * task in an overlapping cpuset. Expose callback_mutex via this
* cpuset_lock() routine, so the oom code can lock it, before
* locking the task list. The tasklist_lock is a spinlock, so
- * must be taken inside callback_sem.
+ * must be taken inside callback_mutex.
*/
void cpuset_lock(void)
{
- down(&callback_sem);
+ mutex_lock(&callback_mutex);
}
/**
void cpuset_unlock(void)
{
- up(&callback_sem);
+ mutex_unlock(&callback_mutex);
}
+/**
+ * cpuset_mem_spread_node() - On which node to begin search for a page
+ *
+ * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
+ * tasks in a cpuset with is_spread_page or is_spread_slab set),
+ * and if the memory allocation used cpuset_mem_spread_node()
+ * to determine on which node to start looking, as it will for
+ * certain page cache or slab cache pages such as used for file
+ * system buffers and inode caches, then instead of starting on the
+ * local node to look for a free page, rather spread the starting
+ * node around the tasks mems_allowed nodes.
+ *
+ * We don't have to worry about the returned node being offline
+ * because "it can't happen", and even if it did, it would be ok.
+ *
+ * The routines calling guarantee_online_mems() are careful to
+ * only set nodes in task->mems_allowed that are online. So it
+ * should not be possible for the following code to return an
+ * offline node. But if it did, that would be ok, as this routine
+ * is not returning the node where the allocation must be, only
+ * the node where the search should start. The zonelist passed to
+ * __alloc_pages() will include all nodes. If the slab allocator
+ * is passed an offline node, it will fall back to the local node.
+ * See kmem_cache_alloc_node().
+ */
+
+int cpuset_mem_spread_node(void)
+{
+ int node;
+
+ node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed);
+ if (node == MAX_NUMNODES)
+ node = first_node(current->mems_allowed);
+ current->cpuset_mem_spread_rotor = node;
+ return node;
+}
+EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
+
/**
* cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors?
* @p: pointer to task_struct of some other task.
* determine if task @p's memory usage might impact the memory
* available to the current task.
*
- * Call while holding callback_sem.
+ * Call while holding callback_mutex.
**/
int cpuset_excl_nodes_overlap(const struct task_struct *p)
* - 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.
+ * and we take manage_mutex, keeping attach_task() from changing it
+ * anyway. No need to check that tsk->cpuset != NULL, thanks to
+ * the_top_cpuset_hack in cpuset_exit(), which sets an exiting tasks
+ * cpuset to top_cpuset.
*/
-
static int proc_cpuset_show(struct seq_file *m, void *v)
{
- struct cpuset *cs;
struct task_struct *tsk;
char *buf;
int retval = 0;
return -ENOMEM;
tsk = m->private;
- down(&manage_sem);
- cs = tsk->cpuset;
- if (!cs) {
- retval = -EINVAL;
- goto out;
- }
-
- retval = cpuset_path(cs, buf, PAGE_SIZE);
+ mutex_lock(&manage_mutex);
+ retval = cpuset_path(tsk->cpuset, buf, PAGE_SIZE);
if (retval < 0)
goto out;
seq_puts(m, buf);
seq_putc(m, '\n');
out:
- up(&manage_sem);
+ mutex_unlock(&manage_mutex);
kfree(buf);
return retval;
}
git.openpandora.org / pandora-kernel.git / blobdiff