diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index f42a17f88699..2c7806873bfd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -194,6 +194,7 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm) mm->mmap = NULL; mm->mmap_cache = NULL; mm->free_area_cache = oldmm->mmap_base; + mm->cached_hole_size = ~0UL; mm->map_count = 0; set_mm_counter(mm, rss, 0); set_mm_counter(mm, anon_rss, 0); @@ -249,8 +250,9 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm) /* * Link in the new vma and copy the page table entries: - * link in first so that swapoff can see swap entries, - * and try_to_unmap_one's find_vma find the new vma. + * link in first so that swapoff can see swap entries. + * Note that, exceptionally, here the vma is inserted + * without holding mm->mmap_sem. */ spin_lock(&mm->page_table_lock); *pprev = tmp; @@ -322,6 +324,7 @@ static struct mm_struct * mm_init(struct mm_struct * mm) mm->ioctx_list = NULL; mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm); mm->free_area_cache = TASK_UNMAPPED_BASE; + mm->cached_hole_size = ~0UL; if (likely(!mm_alloc_pgd(mm))) { mm->def_flags = 0; @@ -1000,9 +1003,6 @@ static task_t *copy_process(unsigned long clone_flags, p->pdeath_signal = 0; p->exit_state = 0; - /* Perform scheduler related setup */ - sched_fork(p); - /* * Ok, make it visible to the rest of the system. * We dont wake it up yet. @@ -1011,18 +1011,24 @@ static task_t *copy_process(unsigned long clone_flags, INIT_LIST_HEAD(&p->ptrace_children); INIT_LIST_HEAD(&p->ptrace_list); + /* Perform scheduler related setup. Assign this task to a CPU. */ + sched_fork(p, clone_flags); + /* Need tasklist lock for parent etc handling! */ write_lock_irq(&tasklist_lock); /* - * The task hasn't been attached yet, so cpus_allowed mask cannot - * have changed. The cpus_allowed mask of the parent may have - * changed after it was copied first time, and it may then move to - * another CPU - so we re-copy it here and set the child's CPU to - * the parent's CPU. This avoids alot of nasty races. + * The task hasn't been attached yet, so its cpus_allowed mask will + * not be changed, nor will its assigned CPU. + * + * The cpus_allowed mask of the parent may have changed after it was + * copied first time - so re-copy it here, then check the child's CPU + * to ensure it is on a valid CPU (and if not, just force it back to + * parent's CPU). This avoids alot of nasty races. */ p->cpus_allowed = current->cpus_allowed; - set_task_cpu(p, smp_processor_id()); + if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed))) + set_task_cpu(p, smp_processor_id()); /* * Check for pending SIGKILL! The new thread should not be allowed |