linux-kernel - [RFC PATCH 01/11] mm/mempolicy: refactor do_set

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Message-Id: <20231122211200.31620-2-gregory.price@memverge.com>
Date:   Wed, 22 Nov 2023 16:11:50 -0500
From:   Gregory Price <gourry.memverge@...il.com>
To:     linux-mm@...ck.org
Cc:     linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-api@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        arnd@...db.de, tglx@...utronix.de, luto@...nel.org,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, mhocko@...nel.org, tj@...nel.org,
        ying.huang@...el.com, Gregory Price <gregory.price@...verge.com>
Subject: [RFC PATCH 01/11] mm/mempolicy: refactor do_set_mempolicy for code re-use

Refactors do_set_mempolicy into replace_mempolicy and do_set_mempolicy
so that replace_mempolicy can be re-used with new code, not just
the system call.

Signed-off-by: Gregory Price <gregory.price@...verge.com>
---
 mm/mempolicy.c | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 10a590ee1c89..410754d56e46 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -809,28 +809,20 @@ static int mbind_range(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	return vma_replace_policy(vma, new_pol);
 }
 
-/* Set the process memory policy */
-static long do_set_mempolicy(unsigned short mode, unsigned short flags,
-			     nodemask_t *nodes)
+/* Attempt to replace mempolicy, release the old one if successful */
+static long replace_mempolicy(struct mempolicy *new, nodemask_t *nodes)
 {
-	struct mempolicy *new, *old;
+	struct mempolicy *old = NULL;
 	NODEMASK_SCRATCH(scratch);
 	int ret;
 
 	if (!scratch)
 		return -ENOMEM;
 
-	new = mpol_new(mode, flags, nodes);
-	if (IS_ERR(new)) {
-		ret = PTR_ERR(new);
-		goto out;
-	}
-
 	task_lock(current);
 	ret = mpol_set_nodemask(new, nodes, scratch);
 	if (ret) {
 		task_unlock(current);
-		mpol_put(new);
 		goto out;
 	}
 
@@ -838,14 +830,32 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
 	current->mempolicy = new;
 	if (new && new->mode == MPOL_INTERLEAVE)
 		current->il_prev = MAX_NUMNODES-1;
+out:
 	task_unlock(current);
 	mpol_put(old);
-	ret = 0;
-out:
+
 	NODEMASK_SCRATCH_FREE(scratch);
 	return ret;
 }
 
+/* Set the process memory policy */
+static long do_set_mempolicy(unsigned short mode, unsigned short flags,
+			     nodemask_t *nodes)
+{
+	struct mempolicy *new;
+	int ret;
+
+	new = mpol_new(mode, flags, nodes);
+	if (IS_ERR(new))
+		return PTR_ERR(new);
+
+	ret = replace_mempolicy(new, nodes);
+	if (ret)
+		mpol_put(new);
+
+	return ret;
+}
+
 /*
  * Return nodemask for policy for get_mempolicy() query
  *
-- 
2.39.1