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>
diff --git a/kernel/fork.c b/kernel/fork.c
index f6f5086..418b52a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -374,12 +374,6 @@
*/
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 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 @@
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 @@
return NULL;
memset(mm, 0, sizeof(*mm));
- mm_init_cpumask(mm);
return mm_init(mm, current);
}
@@ -828,17 +837,10 @@
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 @@
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)