+ z3fold-fix-memory-leak-in-kmem-cache.patch added to -mm tree

+ z3fold-fix-memory-leak-in-kmem-cache.patch added to -mm tree

[akpm]

The patch titled
     Subject: z3fold: fix memory leak in kmem cache
has been added to the -mm tree.  Its filename is
     z3fold-fix-memory-leak-in-kmem-cache.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/z3fold-fix-memory-leak-in-kmem-cache.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/z3fold-fix-memory-leak-in-kmem-cache.patch

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------------------------------------------------------
From: Vitaly Wool <vitalywool@gmail.com>
Subject: z3fold: fix memory leak in kmem cache

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@gmail.com>
Reported-by: Markus Linnala <markus.linnala@gmail.com>
Tested-by: Markus Linnala <markus.linnala@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Henry Burns <henrywolfeburns@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- a/mm/z3fold.c~z3fold-fix-memory-leak-in-kmem-cache
+++ a/mm/z3fold.c
@@ -295,14 +295,11 @@ 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);
@@ -310,6 +307,12 @@ 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);
@@ -930,7 +933,7 @@ 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;
_

Patches currently in -mm which might be from vitalywool@gmail.com are

revert-mm-z3foldc-fix-race-between-migration-and-destruction.patch
z3fold-fix-retry-mechanism-in-page-reclaim.patch
z3fold-fix-memory-leak-in-kmem-cache.patch