linux-kernel - [PATCH 2/2] Revert "staging: zcache: optimize zcache_do

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Date:	Thu, 23 Aug 2012 10:33:11 -0500
From:	Seth Jennings <sjenning@...ux.vnet.ibm.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nitin Gupta <ngupta@...are.org>,
	Minchan Kim <minchan@...nel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	devel@...verdev.osuosl.org
Subject: [PATCH 2/2] Revert "staging: zcache: optimize zcache_do_preload"

This reverts commit 79c0d92c5b6175c1462fbe38bf44180f325aa478.

This commit is resulting  memory corruption in the cleancache case

Signed-off-by: Seth Jennings <sjenning@...ux.vnet.ibm.com>
Reported-by: Dan Magenheimer <dan.magenheimer@...cle.com>
---
 drivers/staging/zcache/zcache-main.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 8a335b9..4f92d87 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -1034,43 +1034,45 @@ static int zcache_do_preload(struct tmem_pool *pool)
 		goto out;
 	if (unlikely(zcache_obj_cache == NULL))
 		goto out;
-
-	/* IRQ has already been disabled. */
+	preempt_disable();
 	kp = &__get_cpu_var(zcache_preloads);
 	while (kp->nr < ARRAY_SIZE(kp->objnodes)) {
+		preempt_enable_no_resched();
 		objnode = kmem_cache_alloc(zcache_objnode_cache,
 				ZCACHE_GFP_MASK);
 		if (unlikely(objnode == NULL)) {
 			zcache_failed_alloc++;
 			goto out;
 		}
-
-		kp->objnodes[kp->nr++] = objnode;
+		preempt_disable();
+		kp = &__get_cpu_var(zcache_preloads);
+		if (kp->nr < ARRAY_SIZE(kp->objnodes))
+			kp->objnodes[kp->nr++] = objnode;
+		else
+			kmem_cache_free(zcache_objnode_cache, objnode);
 	}
-
+	preempt_enable_no_resched();
 	obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK);
 	if (unlikely(obj == NULL)) {
 		zcache_failed_alloc++;
 		goto out;
 	}
-
 	page = (void *)__get_free_page(ZCACHE_GFP_MASK);
 	if (unlikely(page == NULL)) {
 		zcache_failed_get_free_pages++;
 		kmem_cache_free(zcache_obj_cache, obj);
 		goto out;
 	}
-
+	preempt_disable();
+	kp = &__get_cpu_var(zcache_preloads);
 	if (kp->obj == NULL)
 		kp->obj = obj;
 	else
 		kmem_cache_free(zcache_obj_cache, obj);
-
 	if (kp->page == NULL)
 		kp->page = page;
 	else
 		free_page((unsigned long)page);
-
 	ret = 0;
 out:
 	return ret;
@@ -1581,6 +1583,7 @@ static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp,
 				zcache_failed_pers_puts++;
 		}
 		zcache_put_pool(pool);
+		preempt_enable_no_resched();
 	} else {
 		zcache_put_to_flush++;
 		if (atomic_read(&pool->obj_count) > 0)
-- 
1.7.9.5

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