patches/old/mm-cleanup-flags-usage-in-faultin_page.patch

From: Josef Bacik <josef@toxicpanda.com>
Subject: mm: cleanup flags usage in faultin_page
Date: Thu, 18 Jul 2024 17:26:06 -0400

Patch series "mm: some small page fault cleanups".

I was recently wreaking havoc in the page fault code and I noticed some
things that could be cleaned up.  We no longer modify the gup flags in
faultin_page, so we can clean up how we pass the flags in and remove the
extra variable in __get_user_pages.


This patch (of 2):

We're passing a pointer to the foll_flags for faultin_page, however we
never modify the flags in this call.  Change this to just take the flags
value instead.

Link: https://lkml.kernel.org/r/2df51a54c06bdf93e1cb09a19a9ef1df6557b59e.1721337845.git.josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/gup.c |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

--- a/mm/gup.c~mm-cleanup-flags-usage-in-faultin_page
+++ a/mm/gup.c
@@ -1153,19 +1153,19 @@ unmap:
  * to 0 and -EBUSY returned.
  */
 static int faultin_page(struct vm_area_struct *vma,
-		unsigned long address, unsigned int *flags, bool unshare,
+		unsigned long address, unsigned int flags, bool unshare,
 		int *locked)
 {
 	unsigned int fault_flags = 0;
 	vm_fault_t ret;
 
-	if (*flags & FOLL_NOFAULT)
+	if (flags & FOLL_NOFAULT)
 		return -EFAULT;
-	if (*flags & FOLL_WRITE)
+	if (flags & FOLL_WRITE)
 		fault_flags |= FAULT_FLAG_WRITE;
-	if (*flags & FOLL_REMOTE)
+	if (flags & FOLL_REMOTE)
 		fault_flags |= FAULT_FLAG_REMOTE;
-	if (*flags & FOLL_UNLOCKABLE) {
+	if (flags & FOLL_UNLOCKABLE) {
 		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 		/*
 		 * FAULT_FLAG_INTERRUPTIBLE is opt-in. GUP callers must set
@@ -1173,12 +1173,12 @@ static int faultin_page(struct vm_area_s
 		 * That's because some callers may not be prepared to
 		 * handle early exits caused by non-fatal signals.
 		 */
-		if (*flags & FOLL_INTERRUPTIBLE)
+		if (flags & FOLL_INTERRUPTIBLE)
 			fault_flags |= FAULT_FLAG_INTERRUPTIBLE;
 	}
-	if (*flags & FOLL_NOWAIT)
+	if (flags & FOLL_NOWAIT)
 		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
-	if (*flags & FOLL_TRIED) {
+	if (flags & FOLL_TRIED) {
 		/*
 		 * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED
 		 * can co-exist
@@ -1212,7 +1212,7 @@ static int faultin_page(struct vm_area_s
 	}
 
 	if (ret & VM_FAULT_ERROR) {
-		int err = vm_fault_to_errno(ret, *flags);
+		int err = vm_fault_to_errno(ret, flags);
 
 		if (err)
 			return err;
@@ -1490,7 +1490,7 @@ retry:
 
 		page = follow_page_mask(vma, start, foll_flags, &ctx);
 		if (!page || PTR_ERR(page) == -EMLINK) {
-			ret = faultin_page(vma, start, &foll_flags,
+			ret = faultin_page(vma, start, foll_flags,
 					   PTR_ERR(page) == -EMLINK, locked);
 			switch (ret) {
 			case 0:
_