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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.

Vladimir Davydov committed 12 years ago

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

Unified · Split

3 files
  1. fs/exec.c +0 −4
  2. include/linux/mm_types.h +1 −0
  3. 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 if (!mm)368 if (!mm)
369 goto err;369 goto err;
370 370
371 err = init_new_context(current, mm);
372 if (err)
373 goto err;
374
375 err = __bprm_mm_init(bprm);371 err = __bprm_mm_init(bprm);
376 if (err)372 if (err)
377 goto err;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#ifdef CONFIG_CPUMASK_OFFSTACK461#ifdef CONFIG_CPUMASK_OFFSTACK
462 mm->cpu_vm_mask_var = &mm->cpumask_allocation;462 mm->cpu_vm_mask_var = &mm->cpumask_allocation;
463#endif463#endif
464 cpumask_clear(mm->cpu_vm_mask_var);
464}465}
465 466
466/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */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 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);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 rb_link = &mm->mm_rb.rb_node;377 rb_link = &mm->mm_rb.rb_node;
384 rb_parent = NULL;378 rb_parent = NULL;
385 pprev = &mm->mmap;379 pprev = &mm->mmap;
@@ -538,17 +532,27 @@ static void mm_init_aio(struct mm_struct *mm) · 152 unmodified lines
538 532
539static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)533static 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 atomic_set(&mm->mm_users, 1);538 atomic_set(&mm->mm_users, 1);
542 atomic_set(&mm->mm_count, 1);539 atomic_set(&mm->mm_count, 1);
543 init_rwsem(&mm->mmap_sem);540 init_rwsem(&mm->mmap_sem);
544 INIT_LIST_HEAD(&mm->mmlist);541 INIT_LIST_HEAD(&mm->mmlist);
545 mm->core_state = NULL;542 mm->core_state = NULL;
546 atomic_long_set(&mm->nr_ptes, 0);543 atomic_long_set(&mm->nr_ptes, 0);
544 mm->map_count = 0;
545 mm->locked_vm = 0;
547 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));546 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
548 spin_lock_init(&mm->page_table_lock);547 spin_lock_init(&mm->page_table_lock);
548 mm_init_cpumask(mm);
549 mm_init_aio(mm);549 mm_init_aio(mm);
550 mm_init_owner(mm, p);550 mm_init_owner(mm, p);
551 mmu_notifier_mm_init(mm);
551 clear_tlb_flush_pending(mm);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 if (current->mm) {557 if (current->mm) {
554 mm->flags = current->mm->flags & MMF_INIT_MASK;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 mm->def_flags = 0;562 mm->def_flags = 0;
559 }563 }
560 564
561 if (likely(!mm_alloc_pgd(mm))) {565 if (mm_alloc_pgd(mm))
562 mmu_notifier_mm_init(mm);566 goto fail_nopgd;
563 return mm;567
564 }568 if (init_new_context(p, mm))
569 goto fail_nocontext;
565 570
571 return mm;
572
573fail_nocontext:
574 mm_free_pgd(mm);
575fail_nopgd:
566 free_mm(mm);576 free_mm(mm);
567 return NULL;577 return NULL;
568}578}
@@ -596,7 +606,6 @@ struct mm_struct *mm_alloc(void) · 27 unmodified lines
596 return NULL;606 return NULL;
597 607
598 memset(mm, 0, sizeof(*mm));608 memset(mm, 0, sizeof(*mm));
599 mm_init_cpumask(mm);
600 return mm_init(mm, current);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 goto fail_nomem;837 goto fail_nomem;
829 838
830 memcpy(mm, oldmm, sizeof(*mm));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 if (!mm_init(mm, tsk))841 if (!mm_init(mm, tsk))
837 goto fail_nomem;842 goto fail_nomem;
838 843
839 if (init_new_context(tsk, mm))
840 goto fail_nocontext;
841
842 dup_mm_exe_file(oldmm, mm);844 dup_mm_exe_file(oldmm, mm);
843 845
844 err = dup_mmap(mm, oldmm);846 err = dup_mmap(mm, oldmm);
@@ -860,15 +862,6 @@ free_pt: · 15 unmodified lines
860 862
861fail_nomem:863fail_nomem:
862 return NULL;864 return NULL;
863
864fail_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
874static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)867static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)