From 3928d4f5ee37cdc523894f6e549e6aae521d8980 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 21 Jul 2018 13:48:51 -0700 Subject: mm: use helper functions for allocating and freeing vm_area structs The vm_area_struct is one of the most fundamental memory management objects, but the management of it is entirely open-coded evertwhere, ranging from allocation and freeing (using kmem_cache_[z]alloc and kmem_cache_free) to initializing all the fields. We want to unify this in order to end up having some unified initialization of the vmas, and the first step to this is to at least have basic allocation functions. Right now those functions are literally just wrappers around the kmem_cache_*() calls. This is a purely mechanical conversion: # new vma: kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL) -> vm_area_alloc() # copy old vma kmem_cache_alloc(vm_area_cachep, GFP_KERNEL) -> vm_area_dup(old) # free vma kmem_cache_free(vm_area_cachep, vma) -> vm_area_free(vma) to the point where the old vma passed in to the vm_area_dup() function isn't even used yet (because I've left all the old manual initialization alone). Signed-off-by: Linus Torvalds --- kernel/fork.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 9440d61b925c..0e23deb5acfc 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -303,11 +303,26 @@ struct kmem_cache *files_cachep; struct kmem_cache *fs_cachep; /* SLAB cache for vm_area_struct structures */ -struct kmem_cache *vm_area_cachep; +static struct kmem_cache *vm_area_cachep; /* SLAB cache for mm_struct structures (tsk->mm) */ static struct kmem_cache *mm_cachep; +struct vm_area_struct *vm_area_alloc(void) +{ + return kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); +} + +struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) +{ + return kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); +} + +void vm_area_free(struct vm_area_struct *vma) +{ + kmem_cache_free(vm_area_cachep, vma); +} + static void account_kernel_stack(struct task_struct *tsk, int account) { void *stack = task_stack_page(tsk); @@ -455,7 +470,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, goto fail_nomem; charge = len; } - tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); + tmp = vm_area_dup(mpnt); if (!tmp) goto fail_nomem; *tmp = *mpnt; @@ -539,7 +554,7 @@ fail_uprobe_end: fail_nomem_anon_vma_fork: mpol_put(vma_policy(tmp)); fail_nomem_policy: - kmem_cache_free(vm_area_cachep, tmp); + vm_area_free(tmp); fail_nomem: retval = -ENOMEM; vm_unacct_memory(charge); -- cgit v1.2.3 From 95faf6992df468f617edb788da8c21c6eed0dfa7 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 21 Jul 2018 14:48:45 -0700 Subject: mm: make vm_area_dup() actually copy the old vma data .. and re-initialize th eanon_vma_chain head. This removes some boiler-plate from the users, and also makes it clear why it didn't need use the 'zalloc()' version. Signed-off-by: Linus Torvalds --- kernel/fork.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 0e23deb5acfc..67253e41bfb0 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -315,7 +315,13 @@ struct vm_area_struct *vm_area_alloc(void) struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) { - return kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); + struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); + + if (new) { + *new = *orig; + INIT_LIST_HEAD(&new->anon_vma_chain); + } + return new; } void vm_area_free(struct vm_area_struct *vma) @@ -473,8 +479,6 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, tmp = vm_area_dup(mpnt); if (!tmp) goto fail_nomem; - *tmp = *mpnt; - INIT_LIST_HEAD(&tmp->anon_vma_chain); retval = vma_dup_policy(mpnt, tmp); if (retval) goto fail_nomem_policy; -- cgit v1.2.3 From 490fc053865c9cc40f1085ef8a5504f5341f79d2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 21 Jul 2018 15:24:03 -0700 Subject: mm: make vm_area_alloc() initialize core fields Like vm_area_dup(), it initializes the anon_vma_chain head, and the basic mm pointer. The rest of the fields end up being different for different users, although the plan is to also initialize the 'vm_ops' field to a dummy entry. Signed-off-by: Linus Torvalds --- kernel/fork.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 67253e41bfb0..a191c05e757d 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -308,9 +308,15 @@ static struct kmem_cache *vm_area_cachep; /* SLAB cache for mm_struct structures (tsk->mm) */ static struct kmem_cache *mm_cachep; -struct vm_area_struct *vm_area_alloc(void) +struct vm_area_struct *vm_area_alloc(struct mm_struct *mm) { - return kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); + struct vm_area_struct *vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); + + if (vma) { + vma->vm_mm = mm; + INIT_LIST_HEAD(&vma->anon_vma_chain); + } + return vma; } struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) -- cgit v1.2.3 From 027232da7c7c1c7f04383f93bd798e475dde5285 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Thu, 26 Jul 2018 16:37:25 -0700 Subject: mm: introduce vma_init() Not all VMAs allocated with vm_area_alloc(). Some of them allocated on stack or in data segment. The new helper can be use to initialize VMA properly regardless where it was allocated. Link: http://lkml.kernel.org/r/20180724121139.62570-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Acked-by: Linus Torvalds Reviewed-by: Andrew Morton Cc: Dmitry Vyukov Cc: Oleg Nesterov Cc: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index a191c05e757d..1b27babc4c78 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -312,10 +312,8 @@ struct vm_area_struct *vm_area_alloc(struct mm_struct *mm) { struct vm_area_struct *vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); - if (vma) { - vma->vm_mm = mm; - INIT_LIST_HEAD(&vma->anon_vma_chain); - } + if (vma) + vma_init(vma, mm); return vma; } -- cgit v1.2.3