Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "Various fixes and followups"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, compaction: make sure we isolate a valid PFN
  include/linux/generic-radix-tree.h: fix kerneldoc comment
  kernel/signal.c: trace_signal_deliver when signal_group_exit
  drivers/iommu/intel-iommu.c: fix variable 'iommu' set but not used
  spdxcheck.py: fix directory structures
  kasan: initialize tag to 0xff in __kasan_kmalloc
  z3fold: fix sheduling while atomic
  scripts/gdb: fix invocation when CONFIG_COMMON_CLK is not set
  mm/gup: continue VM_FAULT_RETRY processing even for pre-faults
  ocfs2: fix error path kobject memory leak
  memcg: make it work on sparse non-0-node systems
  mm, memcg: consider subtrees in memory.events
  prctl_set_mm: downgrade mmap_sem to read lock
  prctl_set_mm: refactor checks from validate_prctl_map
  kernel/fork.c: make max_threads symbol static
  arch/arm/boot/compressed/decompress.c: fix build error due to lz4 changes
  arch/parisc/configs/c8000_defconfig: remove obsoleted CONFIG_DEBUG_SLAB_LEAK
  mm/vmalloc.c: fix typo in comment
  lib/sort.c: fix kernel-doc notation warnings
  mm: fix Documentation/vm/hmm.rst Sphinx warnings

1 files changed, 8 insertions, 7 deletions

diff --git a/mm/gup.c b/mm/gup.c
index f173fcbaf1b2..ddde097cf9e4 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1042,10 +1042,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 			BUG_ON(ret >= nr_pages);
 		}
 
-		if (!pages)
-			/* If it's a prefault don't insist harder */
-			return ret;
-
 		if (ret > 0) {
 			nr_pages -= ret;
 			pages_done += ret;
@@ -1061,8 +1057,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 				pages_done = ret;
 			break;
 		}
-		/* VM_FAULT_RETRY triggered, so seek to the faulting offset */
-		pages += ret;
+		/*
+		 * VM_FAULT_RETRY triggered, so seek to the faulting offset.
+		 * For the prefault case (!pages) we only update counts.
+		 */
+		if (likely(pages))
+			pages += ret;
 		start += ret << PAGE_SHIFT;
 
 		/*
@@ -1085,7 +1085,8 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 		pages_done++;
 		if (!nr_pages)
 			break;
-		pages++;
+		if (likely(pages))
+			pages++;
 		start += PAGE_SIZE;
 	}
 	if (lock_dropped && *locked) {