mm: unexport __get_user_pages_unlocked()

Unexport 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 commit
1e9877902dc7 ("mm/gup: Introduce get_user_pages_remote()"), so this
appears to have been unintentional and reintroducing it is therefore not
an issue.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20161027095141.2569-3-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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 9 insertions, 6 deletions

diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index efeceb0a..3815e94 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 823544c..de102ca 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1418,13 +1418,12 @@ 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;