diff mbox

[2/2] mm: unexport __get_user_pages_unlocked()

Message ID 20161027095141.2569-3-lstoakes@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Lorenzo Stoakes Oct. 27, 2016, 9:51 a.m. UTC 
This patch unexports the low-level __get_user_pages_unlocked() function and
replaces invocations with calls to more appropriate higher-level functions.

In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked() with
get_user_pages_unlocked() since we can now pass gup_flags.

In async_pf_execute() and process_vm_rw_single_vec() we need to pass different
tsk, mm arguments so get_user_pages_remote() is the sane replacement in these
cases (having added manual acquisition and release of mmap_sem.)

Additionally get_user_pages_remote() reintroduces use of the FOLL_TOUCH
flag. However, this flag was originally silently dropped by 1e9877902dc7e
("mm/gup: Introduce get_user_pages_remote()"), so this appears to have been
unintentional and reintroducing it is therefore not an issue.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
---
 include/linux/mm.h     |  3 ---
 mm/gup.c               |  8 ++++----
 mm/nommu.c             |  7 +++----
 mm/process_vm_access.c | 12 ++++++++----
 virt/kvm/async_pf.c    | 10 +++++++---
 virt/kvm/kvm_main.c    |  5 ++---
 6 files changed, 24 insertions(+), 21 deletions(-)

--
2.10.1
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Comments

Michal Hocko Oct. 27, 2016, 10:57 a.m. UTC | #1 
On Thu 27-10-16 10:51:41, Lorenzo Stoakes wrote:
> This patch unexports the low-level __get_user_pages_unlocked() function and
> replaces invocations with calls to more appropriate higher-level functions.
> 
> In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked() with
> get_user_pages_unlocked() since we can now pass gup_flags.
> 
> In async_pf_execute() and process_vm_rw_single_vec() we need to pass different
> tsk, mm arguments so get_user_pages_remote() is the sane replacement in these
> cases (having added manual acquisition and release of mmap_sem.)
> 
> Additionally get_user_pages_remote() reintroduces use of the FOLL_TOUCH
> flag. However, this flag was originally silently dropped by 1e9877902dc7e
> ("mm/gup: Introduce get_user_pages_remote()"), so this appears to have been
> unintentional and reintroducing it is therefore not an issue.

Looks good to me.
 
> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  include/linux/mm.h     |  3 ---
>  mm/gup.c               |  8 ++++----
>  mm/nommu.c             |  7 +++----
>  mm/process_vm_access.c | 12 ++++++++----
>  virt/kvm/async_pf.c    | 10 +++++++---
>  virt/kvm/kvm_main.c    |  5 ++---
>  6 files changed, 24 insertions(+), 21 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index cc15445..7b2d14e 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1280,9 +1280,6 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
>  			    struct vm_area_struct **vmas);
>  long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
>  		    unsigned int gup_flags, struct page **pages, int *locked);
> -long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> -			       unsigned long start, unsigned long nr_pages,
> -			       struct page **pages, unsigned int gup_flags);
>  long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
>  		    struct page **pages, unsigned int gup_flags);
>  int get_user_pages_fast(unsigned long start, int nr_pages, int write,
> diff --git a/mm/gup.c b/mm/gup.c
> index 0567851..8028af1 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -866,9 +866,10 @@ EXPORT_SYMBOL(get_user_pages_locked);
>   * caller if required (just like with __get_user_pages). "FOLL_GET"
>   * is set implicitly if "pages" is non-NULL.
>   */
> -__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> -					       unsigned long start, unsigned long nr_pages,
> -					       struct page **pages, unsigned int gup_flags)
> +static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk,
> +		struct mm_struct *mm, unsigned long start,
> +		unsigned long nr_pages, struct page **pages,
> +		unsigned int gup_flags)
>  {
>  	long ret;
>  	int locked = 1;
> @@ -880,7 +881,6 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m
>  		up_read(&mm->mmap_sem);
>  	return ret;
>  }
> -EXPORT_SYMBOL(__get_user_pages_unlocked);
> 
>  /*
>   * get_user_pages_unlocked() is suitable to replace the form:
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 8b8faaf..669437b 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -176,9 +176,9 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
>  }
>  EXPORT_SYMBOL(get_user_pages_locked);
> 
> -long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> -			       unsigned long start, unsigned long nr_pages,
> -			       struct page **pages, unsigned int gup_flags)
> +static long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> +				      unsigned long start, unsigned long nr_pages,
> +			              struct page **pages, unsigned int gup_flags)
>  {
>  	long ret;
>  	down_read(&mm->mmap_sem);
> @@ -187,7 +187,6 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
>  	up_read(&mm->mmap_sem);
>  	return ret;
>  }
> -EXPORT_SYMBOL(__get_user_pages_unlocked);
> 
>  long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
>  			     struct page **pages, unsigned int gup_flags)
> diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
> index be8dc8d..84d0c7e 100644
> --- a/mm/process_vm_access.c
> +++ b/mm/process_vm_access.c
> @@ -88,7 +88,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
>  	ssize_t rc = 0;
>  	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
>  		/ sizeof(struct pages *);
> -	unsigned int flags = FOLL_REMOTE;
> +	unsigned int flags = 0;
> 
>  	/* Work out address and page range required */
>  	if (len == 0)
> @@ -100,15 +100,19 @@ static int process_vm_rw_single_vec(unsigned long addr,
> 
>  	while (!rc && nr_pages && iov_iter_count(iter)) {
>  		int pages = min(nr_pages, max_pages_per_loop);
> +		int locked = 1;
>  		size_t bytes;
> 
>  		/*
>  		 * Get the pages we're interested in.  We must
> -		 * add FOLL_REMOTE because task/mm might not
> +		 * access remotely because task/mm might not
>  		 * current/current->mm
>  		 */
> -		pages = __get_user_pages_unlocked(task, mm, pa, pages,
> -						  process_pages, flags);
> +		down_read(&mm->mmap_sem);
> +		pages = get_user_pages_remote(task, mm, pa, pages, flags,
> +					      process_pages, NULL, &locked);
> +		if (locked)
> +			up_read(&mm->mmap_sem);
>  		if (pages <= 0)
>  			return -EFAULT;
> 
> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
> index 8035cc1..dab8b19 100644
> --- a/virt/kvm/async_pf.c
> +++ b/virt/kvm/async_pf.c
> @@ -76,16 +76,20 @@ static void async_pf_execute(struct work_struct *work)
>  	struct kvm_vcpu *vcpu = apf->vcpu;
>  	unsigned long addr = apf->addr;
>  	gva_t gva = apf->gva;
> +	int locked = 1;
> 
>  	might_sleep();
> 
>  	/*
>  	 * This work is run asynchromously to the task which owns
>  	 * mm and might be done in another context, so we must
> -	 * use FOLL_REMOTE.
> +	 * access remotely.
>  	 */
> -	__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
> -			FOLL_WRITE | FOLL_REMOTE);
> +	down_read(&mm->mmap_sem);
> +	get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
> +			&locked);
> +	if (locked)
> +		up_read(&mm->mmap_sem);
> 
>  	kvm_async_page_present_sync(vcpu, apf);
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 2907b7b..c45d951 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1415,13 +1415,12 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
>  		npages = get_user_page_nowait(addr, write_fault, page);
>  		up_read(&current->mm->mmap_sem);
>  	} else {
> -		unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON;
> +		unsigned int flags = FOLL_HWPOISON;
> 
>  		if (write_fault)
>  			flags |= FOLL_WRITE;
> 
> -		npages = __get_user_pages_unlocked(current, current->mm, addr, 1,
> -						   page, flags);
> +		npages = get_user_pages_unlocked(addr, 1, page, flags);
>  	}
>  	if (npages != 1)
>  		return npages;
> --
> 2.10.1
diff mbox

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index cc15445..7b2d14e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1280,9 +1280,6 @@  long get_user_pages(unsigned long start, unsigned long nr_pages,
 			    struct vm_area_struct **vmas);
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 		    unsigned int gup_flags, struct page **pages, int *locked);
-long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
-			       unsigned long start, unsigned long nr_pages,
-			       struct page **pages, unsigned int gup_flags);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 		    struct page **pages, unsigned int gup_flags);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
diff --git a/mm/gup.c b/mm/gup.c
index 0567851..8028af1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -866,9 +866,10 @@  EXPORT_SYMBOL(get_user_pages_locked);
  * caller if required (just like with __get_user_pages). "FOLL_GET"
  * is set implicitly if "pages" is non-NULL.
  */
-__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
-					       unsigned long start, unsigned long nr_pages,
-					       struct page **pages, unsigned int gup_flags)
+static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk,
+		struct mm_struct *mm, unsigned long start,
+		unsigned long nr_pages, struct page **pages,
+		unsigned int gup_flags)
 {
 	long ret;
 	int locked = 1;
@@ -880,7 +881,6 @@  __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m
 		up_read(&mm->mmap_sem);
 	return ret;
 }
-EXPORT_SYMBOL(__get_user_pages_unlocked);

 /*
  * get_user_pages_unlocked() is suitable to replace the form:
diff --git a/mm/nommu.c b/mm/nommu.c
index 8b8faaf..669437b 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -176,9 +176,9 @@  long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 }
 EXPORT_SYMBOL(get_user_pages_locked);

-long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
-			       unsigned long start, unsigned long nr_pages,
-			       struct page **pages, unsigned int gup_flags)
+static long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+				      unsigned long start, unsigned long nr_pages,
+			              struct page **pages, unsigned int gup_flags)
 {
 	long ret;
 	down_read(&mm->mmap_sem);
@@ -187,7 +187,6 @@  long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 	up_read(&mm->mmap_sem);
 	return ret;
 }
-EXPORT_SYMBOL(__get_user_pages_unlocked);

 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 			     struct page **pages, unsigned int gup_flags)
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index be8dc8d..84d0c7e 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -88,7 +88,7 @@  static int process_vm_rw_single_vec(unsigned long addr,
 	ssize_t rc = 0;
 	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
 		/ sizeof(struct pages *);
-	unsigned int flags = FOLL_REMOTE;
+	unsigned int flags = 0;

 	/* Work out address and page range required */
 	if (len == 0)
@@ -100,15 +100,19 @@  static int process_vm_rw_single_vec(unsigned long addr,

 	while (!rc && nr_pages && iov_iter_count(iter)) {
 		int pages = min(nr_pages, max_pages_per_loop);
+		int locked = 1;
 		size_t bytes;

 		/*
 		 * Get the pages we're interested in.  We must
-		 * add FOLL_REMOTE because task/mm might not
+		 * access remotely because task/mm might not
 		 * current/current->mm
 		 */
-		pages = __get_user_pages_unlocked(task, mm, pa, pages,
-						  process_pages, flags);
+		down_read(&mm->mmap_sem);
+		pages = get_user_pages_remote(task, mm, pa, pages, flags,
+					      process_pages, NULL, &locked);
+		if (locked)
+			up_read(&mm->mmap_sem);
 		if (pages <= 0)
 			return -EFAULT;

diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 8035cc1..dab8b19 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -76,16 +76,20 @@  static void async_pf_execute(struct work_struct *work)
 	struct kvm_vcpu *vcpu = apf->vcpu;
 	unsigned long addr = apf->addr;
 	gva_t gva = apf->gva;
+	int locked = 1;

 	might_sleep();

 	/*
 	 * This work is run asynchromously to the task which owns
 	 * mm and might be done in another context, so we must
-	 * use FOLL_REMOTE.
+	 * access remotely.
 	 */
-	__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
-			FOLL_WRITE | FOLL_REMOTE);
+	down_read(&mm->mmap_sem);
+	get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
+			&locked);
+	if (locked)
+		up_read(&mm->mmap_sem);

 	kvm_async_page_present_sync(vcpu, apf);

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2907b7b..c45d951 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1415,13 +1415,12 @@  static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
 		npages = get_user_page_nowait(addr, write_fault, page);
 		up_read(&current->mm->mmap_sem);
 	} else {
-		unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON;
+		unsigned int flags = FOLL_HWPOISON;

 		if (write_fault)
 			flags |= FOLL_WRITE;

-		npages = __get_user_pages_unlocked(current, current->mm, addr, 1,
-						   page, flags);
+		npages = get_user_pages_unlocked(addr, 1, page, flags);
 	}
 	if (npages != 1)
 		return npages;