mm/mempolicy: remove or narrow the lock on current

It is not necessary to hold the lock of current when setting nodemask of a new policy. Signed-off-by: Wei Yang <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Reviewed-by: Andrew Morton <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Linus Torvalds <[email protected]>
jangid · Oct 14, 2020 · 78b132e · 78b132e
1 parent 1100262
commit 78b132e
Showing 1 changed file with 1 addition and 4 deletions.
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
@@ -875,13 +875,12 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
 		goto out;
 	}
 
-	task_lock(current);
 	ret = mpol_set_nodemask(new, nodes, scratch);
 	if (ret) {
-		task_unlock(current);
 		mpol_put(new);
 		goto out;
 	}
+	task_lock(current);
 	old = current->mempolicy;
 	current->mempolicy = new;
 	if (new && new->mode == MPOL_INTERLEAVE)
@@ -1324,9 +1323,7 @@ static long do_mbind(unsigned long start, unsigned long len,
 		NODEMASK_SCRATCH(scratch);
 		if (scratch) {
 			mmap_write_lock(mm);
-			task_lock(current);
 			err = mpol_set_nodemask(new, nmask, scratch);
-			task_unlock(current);
 			if (err)
 				mmap_write_unlock(mm);
 		} else