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Date: Thu, 19 Jun 2014 13:07:46 +0400
From: Vladimir Davydov <vdavydov@...allels.com>
To: <akpm@...ux-foundation.org>
CC: <oleg@...hat.com>, <rientjes@...gle.com>, <cl@...ux.com>,
<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/3] 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@...allels.com>
---
fs/exec.c | 4 ----
include/linux/mm_types.h | 1 +
kernel/fork.c | 47 ++++++++++++++++++++--------------------------
3 files changed, 21 insertions(+), 31 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index a3d33fe592d6..2ef2751f5a8d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -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;
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 96c5750e3110..21bff4be4379 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. */
diff --git a/kernel/fork.c b/kernel/fork.c
index d2799d1fc952..01f0d0c56cb9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -365,12 +365,6 @@ 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;
@@ -529,17 +523,27 @@ 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;
@@ -549,11 +553,17 @@ 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;
}
@@ -587,7 +597,6 @@ struct mm_struct *mm_alloc(void)
return NULL;
memset(mm, 0, sizeof(*mm));
- mm_init_cpumask(mm);
return mm_init(mm, current);
}
@@ -819,17 +828,10 @@ 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);
@@ -851,15 +853,6 @@ 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)
--
1.7.10.4
--
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