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>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 796deac19fcf..6e0b286649f1 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -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. */