mm: add locked parameter to get_user_pages_remote()

Patch series "mm: unexport __get_user_pages_unlocked()".

This patch series continues the cleanup of get_user_pages*() functions
taking advantage of the fact we can now pass gup_flags as we please.

It firstly adds an additional 'locked' parameter to
get_user_pages_remote() to allow for its callers to utilise
VM_FAULT_RETRY functionality.  This is necessary as the invocation of
__get_user_pages_unlocked() in process_vm_rw_single_vec() makes use of
this and no other existing higher level function would allow it to do
so.

Secondly existing callers of __get_user_pages_unlocked() are replaced
with the appropriate higher-level replacement -
get_user_pages_unlocked() if the current task and memory descriptor are
referenced, or get_user_pages_remote() if other task/memory descriptors
are referenced (having acquiring mmap_sem.)

This patch (of 2):

Add a int *locked parameter to get_user_pages_remote() to allow
VM_FAULT_RETRY faulting behaviour similar to get_user_pages_[un]locked().

Taking into account the previous adjustments to get_user_pages*()
functions allowing for the passing of gup_flags, we are now in a
position where __get_user_pages_unlocked() need only be exported for his
ability to allow VM_FAULT_RETRY behaviour, this adjustment allows us to
subsequently unexport __get_user_pages_unlocked() as well as allowing
for future flexibility in the use of get_user_pages_remote().

[sfr@canb.auug.org.au: merge fix for get_user_pages_remote API change]
  Link: http://lkml.kernel.org/r/20161122210511.024ec341@canb.auug.org.au
Link: http://lkml.kernel.org/r/20161027095141.2569-2-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

10 files changed, 18 insertions, 14 deletions

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 7d066a9..6f5dfab 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -759,7 +759,7 @@ static struct page **etnaviv_gem_userptr_do_get_pages(
 	down_read(&mm->mmap_sem);
 	while (pinned < npages) {
 		ret = get_user_pages_remote(task, mm, ptr, npages - pinned,
-					    flags, pvec + pinned, NULL);
+					    flags, pvec + pinned, NULL, NULL);
 		if (ret < 0)
 			break;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 107ddf5..d068af2 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -515,7 +515,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
 					 obj->userptr.ptr + pinned * PAGE_SIZE,
 					 npages - pinned,
 					 flags,
-					 pvec + pinned, NULL);
+					 pvec + pinned, NULL, NULL);
 				if (ret < 0)
 					break;
 
diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 1f0fe32..6b079a3 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -578,7 +578,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
 		 */
 		npages = get_user_pages_remote(owning_process, owning_mm,
 				user_virt, gup_num_pages,
-				flags, local_page_list, NULL);
+				flags, local_page_list, NULL, NULL);
 		up_read(&owning_mm->mmap_sem);
 
 		if (npages < 0)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 9815e45..f3726ba 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -362,7 +362,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 
 		down_read(&mm->mmap_sem);
 		ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
-					    NULL);
+					    NULL, NULL);
 		up_read(&mm->mmap_sem);
 	}
 
diff --git a/fs/exec.c b/fs/exec.c
index 923c57d..eac6088 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -209,7 +209,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 	 * doing the exec and bprm->mm is the new process's mm.
 	 */
 	ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
-			&page, NULL);
+			&page, NULL, NULL);
 	if (ret <= 0)
 		return NULL;
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a92c8d7..cc15445 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1274,7 +1274,7 @@ extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
 long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 			    unsigned long start, unsigned long nr_pages,
 			    unsigned int gup_flags, struct page **pages,
-			    struct vm_area_struct **vmas);
+			    struct vm_area_struct **vmas, int *locked);
 long get_user_pages(unsigned long start, unsigned long nr_pages,
 			    unsigned int gup_flags, struct page **pages,
 			    struct vm_area_struct **vmas);
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f9ec9ad..215871b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -301,7 +301,7 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
 retry:
 	/* Read the page with vaddr into memory */
 	ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page,
-			&vma);
+			&vma, NULL);
 	if (ret <= 0)
 		return ret;
 
@@ -1712,7 +1712,7 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
 	 * essentially a kernel access to the memory.
 	 */
 	result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page,
-			NULL);
+			NULL, NULL);
 	if (result < 0)
 		return result;
 
diff --git a/mm/gup.c b/mm/gup.c
index e50178c..b64c907 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -917,6 +917,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  *		only intends to ensure the pages are faulted in.
  * @vmas:	array of pointers to vmas corresponding to each page.
  *		Or NULL if the caller does not require them.
+ * @locked:	pointer to lock flag indicating whether lock is held and
+ *		subsequently whether VM_FAULT_RETRY functionality can be
+ *		utilised. Lock must initially be held.
  *
  * Returns number of pages pinned. This may be fewer than the number
  * requested. If nr_pages is 0 or negative, returns 0. If no pages
@@ -960,10 +963,10 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
 long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 		unsigned long start, unsigned long nr_pages,
 		unsigned int gup_flags, struct page **pages,
-		struct vm_area_struct **vmas)
+		struct vm_area_struct **vmas, int *locked)
 {
 	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
-				       NULL, false,
+				       locked, true,
 				       gup_flags | FOLL_TOUCH | FOLL_REMOTE);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
@@ -971,8 +974,9 @@ EXPORT_SYMBOL(get_user_pages_remote);
 /*
  * This is the same as get_user_pages_remote(), just with a
  * less-flexible calling convention where we assume that the task
- * and mm being operated on are the current task's.  We also
- * obviously don't pass FOLL_REMOTE in here.
+ * and mm being operated on are the current task's and don't allow
+ * passing of a locked parameter.  We also obviously don't pass
+ * FOLL_REMOTE in here.
  */
 long get_user_pages(unsigned long start, unsigned long nr_pages,
 		unsigned int gup_flags, struct page **pages,
diff --git a/mm/memory.c b/mm/memory.c
index c264f7c..3a6a123 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3919,7 +3919,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 		struct page *page = NULL;
 
 		ret = get_user_pages_remote(tsk, mm, addr, 1,
-				gup_flags, &page, &vma);
+				gup_flags, &page, &vma, NULL);
 		if (ret <= 0) {
 #ifndef CONFIG_HAVE_IOREMAP_PROT
 			break;
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 682b73a..838ffa7 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -881,7 +881,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
 	 * the execve().
 	 */
 	if (get_user_pages_remote(current, bprm->mm, pos, 1,
-				FOLL_FORCE, &page, NULL) <= 0)
+				FOLL_FORCE, &page, NULL, NULL) <= 0)
 		return false;
 #else
 	page = bprm->page[pos / PAGE_SIZE];