linux-kernel - [PATCH 5.2 265/313] z3fold: fix memory leak in kmem cache

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Message-Id: <20191003154559.153678471@linuxfoundation.org>
Date:   Thu,  3 Oct 2019 17:54:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vitaly Wool <vitalywool@...il.com>,
        Markus Linnala <markus.linnala@...il.com>,
        Dan Streetman <ddstreet@...e.org>,
        Henry Burns <henrywolfeburns@...il.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.2 265/313] z3fold: fix memory leak in kmem cache

From: Vitaly Wool <vitalywool@...il.com>

commit 63398413c00c7836ea87a1fa205c91d2199b25cf upstream.

Currently there is a leak in init_z3fold_page() -- it allocates handles
from kmem cache even for headless pages, but then they are never used and
never freed, so eventually kmem cache may get exhausted.  This patch
provides a fix for that.

Link: http://lkml.kernel.org/r/20190917185352.44cf285d3ebd9e64548de5de@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@...il.com>
Reported-by: Markus Linnala <markus.linnala@...il.com>
Tested-by: Markus Linnala <markus.linnala@...il.com>
Cc: Dan Streetman <ddstreet@...e.org>
Cc: Henry Burns <henrywolfeburns@...il.com>
Cc: Shakeel Butt <shakeelb@...gle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 mm/z3fold.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -297,14 +297,11 @@ static void z3fold_unregister_migration(
  }
 
 /* Initializes the z3fold header of a newly allocated z3fold page */
-static struct z3fold_header *init_z3fold_page(struct page *page,
+static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
 					struct z3fold_pool *pool, gfp_t gfp)
 {
 	struct z3fold_header *zhdr = page_address(page);
-	struct z3fold_buddy_slots *slots = alloc_slots(pool, gfp);
-
-	if (!slots)
-		return NULL;
+	struct z3fold_buddy_slots *slots;
 
 	INIT_LIST_HEAD(&page->lru);
 	clear_bit(PAGE_HEADLESS, &page->private);
@@ -312,6 +309,12 @@ static struct z3fold_header *init_z3fold
 	clear_bit(NEEDS_COMPACTING, &page->private);
 	clear_bit(PAGE_STALE, &page->private);
 	clear_bit(PAGE_CLAIMED, &page->private);
+	if (headless)
+		return zhdr;
+
+	slots = alloc_slots(pool, gfp);
+	if (!slots)
+		return NULL;
 
 	spin_lock_init(&zhdr->page_lock);
 	kref_init(&zhdr->refcount);
@@ -932,7 +935,7 @@ retry:
 	if (!page)
 		return -ENOMEM;
 
-	zhdr = init_z3fold_page(page, pool, gfp);
+	zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
 	if (!zhdr) {
 		__free_page(page);
 		return -ENOMEM;