linux-kernel - [PATCH] Staging: zram: Fix kunmapping order

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Date:	Wed, 13 Jul 2011 17:20:05 +0200
From:	Jerome Marchand <jmarchan@...hat.com>
To:	Greg Kroah-Hartman <gregkh@...e.de>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Nitin Gupta <ngupta@...are.org>
Subject: [PATCH] Staging: zram: Fix kunmapping order


This patch fixes the unmapping order of KM_USER0/1 in
handle_uncompressed_page() and zram_read() so that kmap()/kunmap() calls
are correctly nested.

Reported-by: Nitin Gupta <ngupta@...are.org>
Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
---
 zram_drv.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index c5fdc55..d70ec1a 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -199,8 +199,8 @@ static void handle_uncompressed_page(struct zram *zram, struct bio_vec *bvec,
 	cmem = kmap_atomic(zram->table[index].page, KM_USER1);
 
 	memcpy(user_mem + bvec->bv_offset, cmem + offset, bvec->bv_len);
-	kunmap_atomic(user_mem, KM_USER0);
 	kunmap_atomic(cmem, KM_USER1);
+	kunmap_atomic(user_mem, KM_USER0);
 
 	flush_dcache_page(page);
 }
@@ -267,8 +267,8 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 		kfree(uncmem);
 	}
 
-	kunmap_atomic(user_mem, KM_USER0);
 	kunmap_atomic(cmem, KM_USER1);
+	kunmap_atomic(user_mem, KM_USER0);
 
 	/* Should NEVER happen. Return bio error if it does. */
 	if (unlikely(ret != LZO_E_OK)) {
--
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