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[199.115.105.18]) by mx.google.com with ESMTPS id l7si7249010lbr.68.2014.06.19.02.08.04 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Jun 2014 02:08:04 -0700 (PDT) From: Vladimir Davydov Subject: [PATCH 1/3] fork/exec: cleanup mm initialization Date: Thu, 19 Jun 2014 13:07:46 +0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: oleg@redhat.com, rientjes@google.com, cl@linux.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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 --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org