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fork/exec: cleanup mm initialization 

mm initialization on fork/exec is spread all over the place, which makes
the code look inconsistent.

We have mm_init(), which is supposed to init/nullify mm's internals, but
it doesn't init all the fields it should:

 - on fork ->mmap,mm_rb,vmacache_seqnum,map_count,mm_cpumask,locked_vm
   are zeroed in dup_mmap();

 - on fork ->pmd_huge_pte is zeroed in dup_mm(), immediately before
   calling mm_init();

 - ->cpu_vm_mask_var ptr is initialized by mm_init_cpumask(), which is
   called before mm_init() on both fork and exec;

 - ->context is initialized by init_new_context(), which is called after
   mm_init() on both fork and exec;

Let's consolidate all the initializations in mm_init() to make the code
look cleaner.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Vladimir Davydov 2014-08-08 14:21:56 -07:00 committed by Linus Torvalds
parent 8f053ac11f
commit 41f727fde1
3 changed files with 21 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/exec.c
View File

@ -368,10 +368,6 @@ static int bprm_mm_init(struct linux_binprm *bprm)
if (!mm)
goto err;
err = init_new_context(current, mm);
if (err)
goto err;
err = __bprm_mm_init(bprm);
if (err)
goto err;

1
include/linux/mm_types.h
View File

@ -461,6 +461,7 @@ static inline void mm_init_cpumask(struct mm_struct *mm)
#ifdef CONFIG_CPUMASK_OFFSTACK
mm->cpu_vm_mask_var = &mm->cpumask_allocation;
#endif
cpumask_clear(mm->cpu_vm_mask_var);
}
/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */

47
kernel/fork.c
View File

@ -374,12 +374,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
*/
down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
mm->locked_vm = 0;
mm->mmap = NULL;
mm->vmacache_seqnum = 0;
mm->map_count = 0;
cpumask_clear(mm_cpumask(mm));
mm->mm_rb = RB_ROOT;
rb_link = &mm->mm_rb.rb_node;
rb_parent = NULL;
pprev = &mm->mmap;
@ -538,17 +532,27 @@ static void mm_init_aio(struct mm_struct *mm)
static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
{
mm->mmap = NULL;
mm->mm_rb = RB_ROOT;
mm->vmacache_seqnum = 0;
atomic_set(&mm->mm_users, 1);
atomic_set(&mm->mm_count, 1);
init_rwsem(&mm->mmap_sem);
INIT_LIST_HEAD(&mm->mmlist);
mm->core_state = NULL;
atomic_long_set(&mm->nr_ptes, 0);
mm->map_count = 0;
mm->locked_vm = 0;
memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
spin_lock_init(&mm->page_table_lock);
mm_init_cpumask(mm);
mm_init_aio(mm);
mm_init_owner(mm, p);
mmu_notifier_mm_init(mm);
clear_tlb_flush_pending(mm);
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
mm->pmd_huge_pte = NULL;
#endif
if (current->mm) {
mm->flags = current->mm->flags & MMF_INIT_MASK;
@ -558,11 +562,17 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
mm->def_flags = 0;
}
if (likely(!mm_alloc_pgd(mm))) {
mmu_notifier_mm_init(mm);
return mm;
}
if (mm_alloc_pgd(mm))
goto fail_nopgd;
if (init_new_context(p, mm))
goto fail_nocontext;
return mm;
fail_nocontext:
mm_free_pgd(mm);
fail_nopgd:
free_mm(mm);
return NULL;
}
@ -596,7 +606,6 @@ struct mm_struct *mm_alloc(void)
return NULL;
memset(mm, 0, sizeof(*mm));
mm_init_cpumask(mm);
return mm_init(mm, current);
}
@ -828,17 +837,10 @@ static struct mm_struct *dup_mm(struct task_struct *tsk)
goto fail_nomem;
memcpy(mm, oldmm, sizeof(*mm));
mm_init_cpumask(mm);
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
mm->pmd_huge_pte = NULL;
#endif
if (!mm_init(mm, tsk))
goto fail_nomem;
if (init_new_context(tsk, mm))
goto fail_nocontext;
dup_mm_exe_file(oldmm, mm);
err = dup_mmap(mm, oldmm);
@ -860,15 +862,6 @@ free_pt:
fail_nomem:
return NULL;
fail_nocontext:
/*
* If init_new_context() failed, we cannot use mmput() to free the mm
* because it calls destroy_context()
*/
mm_free_pgd(mm);
free_mm(mm);
return NULL;
}
static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)