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.

Vladimir Davydov committed 12 years ago

Commit 41f727f1 parent 8f053ac3 files · +21 −31Browse files

Unified · Split

3 files

fs/exec.c +0 −4
include/linux/mm_types.h +1 −0
kernel/fork.c +20 −27

fs/exec.c+0−4

@@ -368,10 +368,6 @@ static int bprm_mm_init(struct linux_binprm *bprm) · 367 unmodified lines
368	368	if (!mm)
369	369	goto err;
370	370
371		− err = init_new_context(current, mm);
372		− if (err)
373		− goto err;
374		−
375	371	err = __bprm_mm_init(bprm);
376	372	if (err)
377	373	goto err;

include/linux/mm_types.h+1−0

@@ -461,6 +461,7 @@ static inline void mm_init_cpumask(struct mm_struct *mm) · 460 unmodified lines
461	461	#ifdef CONFIG_CPUMASK_OFFSTACK
462	462	mm->cpu_vm_mask_var = &mm->cpumask_allocation;
463	463	#endif
	464	+ cpumask_clear(mm->cpu_vm_mask_var);
464	465	}
465	466
466	467	/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */

kernel/fork.c+20−27

@@ -374,12 +374,6 @@ static int dup_mmap(struct mm_struct mm, struct mm_struct oldmm) · 373 unmodified lines
374	374	*/
375	375	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
376	376
377		− mm->locked_vm = 0;
378		− mm->mmap = NULL;
379		− mm->vmacache_seqnum = 0;
380		− mm->map_count = 0;
381		− cpumask_clear(mm_cpumask(mm));
382		− mm->mm_rb = RB_ROOT;
383	377	rb_link = &mm->mm_rb.rb_node;
384	378	rb_parent = NULL;
385	379	pprev = &mm->mmap;
@@ -538,17 +532,27 @@ static void mm_init_aio(struct mm_struct *mm) · 152 unmodified lines
538	532
539	533	static struct mm_struct mm_init(struct mm_struct mm, struct task_struct *p)
540	534	{
	535	+ mm->mmap = NULL;
	536	+ mm->mm_rb = RB_ROOT;
	537	+ mm->vmacache_seqnum = 0;
541	538	atomic_set(&mm->mm_users, 1);
542	539	atomic_set(&mm->mm_count, 1);
543	540	init_rwsem(&mm->mmap_sem);
544	541	INIT_LIST_HEAD(&mm->mmlist);
545	542	mm->core_state = NULL;
546	543	atomic_long_set(&mm->nr_ptes, 0);
	544	+ mm->map_count = 0;
	545	+ mm->locked_vm = 0;
547	546	memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
548	547	spin_lock_init(&mm->page_table_lock);
	548	+ mm_init_cpumask(mm);
549	549	mm_init_aio(mm);
550	550	mm_init_owner(mm, p);
	551	+ mmu_notifier_mm_init(mm);
551	552	clear_tlb_flush_pending(mm);
	553	+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
	554	+ mm->pmd_huge_pte = NULL;
	555	+#endif
552	556
553	557	if (current->mm) {
554	558	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) · 3 unmodified lines
558	562	mm->def_flags = 0;
559	563	}
560	564
561		− if (likely(!mm_alloc_pgd(mm))) {
562		− mmu_notifier_mm_init(mm);
563		− return mm;
564		− }
	565	+ if (mm_alloc_pgd(mm))
	566	+ goto fail_nopgd;
	567	+
	568	+ if (init_new_context(p, mm))
	569	+ goto fail_nocontext;
565	570
	571	+ return mm;
	572	+
	573	+fail_nocontext:
	574	+ mm_free_pgd(mm);
	575	+fail_nopgd:
566	576	free_mm(mm);
567	577	return NULL;
568	578	}
@@ -596,7 +606,6 @@ struct mm_struct *mm_alloc(void) · 27 unmodified lines
596	606	return NULL;
597	607
598	608	memset(mm, 0, sizeof(*mm));
599		− mm_init_cpumask(mm);
600	609	return mm_init(mm, current);
601	610	}
602	611
@@ -828,17 +837,10 @@ static struct mm_struct dup_mm(struct task_struct tsk) · 225 unmodified lines
828	837	goto fail_nomem;
829	838
830	839	memcpy(mm, oldmm, sizeof(*mm));
831		− mm_init_cpumask(mm);
832	840
833		−#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
834		− mm->pmd_huge_pte = NULL;
835		−#endif
836	841	if (!mm_init(mm, tsk))
837	842	goto fail_nomem;
838	843
839		− if (init_new_context(tsk, mm))
840		− goto fail_nocontext;
841		−
842	844	dup_mm_exe_file(oldmm, mm);
843	845
844	846	err = dup_mmap(mm, oldmm);
@@ -860,15 +862,6 @@ free_pt: · 15 unmodified lines
860	862
861	863	fail_nomem:
862	864	return NULL;
863		−
864		−fail_nocontext:
865		− /*
866		− * If init_new_context() failed, we cannot use mmput() to free the mm
867		− * because it calls destroy_context()
868		− */
869		− mm_free_pgd(mm);
870		− free_mm(mm);
871		− return NULL;
872	865	}
873	866
874	867	static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)