[PATCH] staging: zcache: fix highmem crash on 32-bit

[PATCH] staging: zcache: fix highmem crash on 32-bit

[Seth Jennings]

After commit 966b9016a1, zcache_put_page() was modified to pass
page_address(page) instead of the actual page pointer. In
combination with the function signature changes to tmem_put()
and zcache_pampd_create(), zcache_pampd_create() tries to (re)derive
the page structure from the virtual address.  However, if the
original page is a high memory page (or any unmapped page),
this virt_to_page() fails because the page_address() in
zcache_put_page() returned NULL.

This patch changes zcache_put_page() and zcache_get_page() to pass
the page structure instead of the page's virtual address, which
may or may not exist.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
---
 drivers/staging/zcache/zcache-main.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 855a5bb..a3f5162 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -1158,7 +1158,7 @@ static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
 	size_t clen;
 	int ret;
 	unsigned long count;
-	struct page *page = virt_to_page(data);
+	struct page *page = (struct page *)(data);
 	struct zcache_client *cli = pool->client;
 	uint16_t client_id = get_client_id_from_client(cli);
 	unsigned long zv_mean_zsize;
@@ -1227,7 +1227,7 @@ static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw,
 	int ret = 0;
 
 	BUG_ON(is_ephemeral(pool));
-	zv_decompress(virt_to_page(data), pampd);
+	zv_decompress((struct page *)(data), pampd);
 	return ret;
 }
 
@@ -1539,7 +1539,7 @@ static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp,
 		goto out;
 	if (!zcache_freeze && zcache_do_preload(pool) == 0) {
 		/* preload does preempt_disable on success */
-		ret = tmem_put(pool, oidp, index, page_address(page),
+		ret = tmem_put(pool, oidp, index, (char *)(page),
 				PAGE_SIZE, 0, is_ephemeral(pool));
 		if (ret < 0) {
 			if (is_ephemeral(pool))
@@ -1572,7 +1572,7 @@ static int zcache_get_page(int cli_id, int pool_id, struct tmem_oid *oidp,
 	pool = zcache_get_pool_by_id(cli_id, pool_id);
 	if (likely(pool != NULL)) {
 		if (atomic_read(&pool->obj_count) > 0)
-			ret = tmem_get(pool, oidp, index, page_address(page),
+			ret = tmem_get(pool, oidp, index, (char *)(page),
 					&size, 0, is_ephemeral(pool));
 		zcache_put_pool(pool);
 	}
-- 
1.7.4.1

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Re: [PATCH] staging: zcache: fix highmem crash on 32-bit

[Seth Jennings]

Please disregard, I sent this one out before on 8/10 :-/

Sorry for the noise.

I couldn't find the original post in the LKML archives, 
so I thought I had never sent it.  Turns out that I only 
sent it to the driver project list.

On 08/23/2011 11:06 AM, Seth Jennings wrote:
> After commit 966b9016a1, zcache_put_page() was modified to pass
> page_address(page) instead of the actual page pointer. In
> combination with the function signature changes to tmem_put()
> and zcache_pampd_create(), zcache_pampd_create() tries to (re)derive
> the page structure from the virtual address.  However, if the
> original page is a high memory page (or any unmapped page),
> this virt_to_page() fails because the page_address() in
> zcache_put_page() returned NULL.
> 
> This patch changes zcache_put_page() and zcache_get_page() to pass
> the page structure instead of the page's virtual address, which
> may or may not exist.
> 
> Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
> ---
>  drivers/staging/zcache/zcache-main.c |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
> index 855a5bb..a3f5162 100644
> --- a/drivers/staging/zcache/zcache-main.c
> +++ b/drivers/staging/zcache/zcache-main.c
> @@ -1158,7 +1158,7 @@ static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
>  	size_t clen;
>  	int ret;
>  	unsigned long count;
> -	struct page *page = virt_to_page(data);
> +	struct page *page = (struct page *)(data);
>  	struct zcache_client *cli = pool->client;
>  	uint16_t client_id = get_client_id_from_client(cli);
>  	unsigned long zv_mean_zsize;
> @@ -1227,7 +1227,7 @@ static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw,
>  	int ret = 0;
> 
>  	BUG_ON(is_ephemeral(pool));
> -	zv_decompress(virt_to_page(data), pampd);
> +	zv_decompress((struct page *)(data), pampd);
>  	return ret;
>  }
> 
> @@ -1539,7 +1539,7 @@ static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp,
>  		goto out;
>  	if (!zcache_freeze && zcache_do_preload(pool) == 0) {
>  		/* preload does preempt_disable on success */
> -		ret = tmem_put(pool, oidp, index, page_address(page),
> +		ret = tmem_put(pool, oidp, index, (char *)(page),
>  				PAGE_SIZE, 0, is_ephemeral(pool));
>  		if (ret < 0) {
>  			if (is_ephemeral(pool))
> @@ -1572,7 +1572,7 @@ static int zcache_get_page(int cli_id, int pool_id, struct tmem_oid *oidp,
>  	pool = zcache_get_pool_by_id(cli_id, pool_id);
>  	if (likely(pool != NULL)) {
>  		if (atomic_read(&pool->obj_count) > 0)
> -			ret = tmem_get(pool, oidp, index, page_address(page),
> +			ret = tmem_get(pool, oidp, index, (char *)(page),
>  					&size, 0, is_ephemeral(pool));
>  		zcache_put_pool(pool);
>  	}

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