* [PATCH] zram: avoid kunmap_atomic a NULL pointer
@ 2014-10-30 6:20 Weijie Yang
2014-10-30 13:13 ` Jerome Marchand
2014-10-31 13:46 ` Sergey Senozhatsky
0 siblings, 2 replies; 3+ messages in thread
From: Weijie Yang @ 2014-10-30 6:20 UTC (permalink / raw)
To: 'Minchan Kim'
Cc: 'Andrew Morton', 'Sergey Senozhatsky',
'Dan Streetman', 'Nitin Gupta',
'Weijie Yang', 'Linux-MM', 'linux-kernel'
zram could kunmap_atomic a NULL pointer in a rare situation:
a zram page become a full-zeroed page after a partial write io.
The current code doesn't handle this case and kunmap_atomic a
NULL porinter, which panic the kernel.
This patch fixes this issue.
Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
---
drivers/block/zram/zram_drv.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 2ad0b5b..3920ee4 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -560,7 +560,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
}
if (page_zero_filled(uncmem)) {
- kunmap_atomic(user_mem);
+ if (user_mem)
+ kunmap_atomic(user_mem);
/* Free memory associated with this sector now. */
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
zram_free_page(zram, index);
--
1.7.0.4
--
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^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] zram: avoid kunmap_atomic a NULL pointer
2014-10-30 6:20 [PATCH] zram: avoid kunmap_atomic a NULL pointer Weijie Yang
@ 2014-10-30 13:13 ` Jerome Marchand
2014-10-31 13:46 ` Sergey Senozhatsky
1 sibling, 0 replies; 3+ messages in thread
From: Jerome Marchand @ 2014-10-30 13:13 UTC (permalink / raw)
To: Weijie Yang, 'Minchan Kim'
Cc: 'Andrew Morton', 'Sergey Senozhatsky',
'Dan Streetman', 'Nitin Gupta',
'Weijie Yang', 'Linux-MM', 'linux-kernel'
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On 10/30/2014 02:20 AM, Weijie Yang wrote:
> zram could kunmap_atomic a NULL pointer in a rare situation:
> a zram page become a full-zeroed page after a partial write io.
> The current code doesn't handle this case and kunmap_atomic a
> NULL porinter, which panic the kernel.
>
> This patch fixes this issue.
>
> Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
> ---
> drivers/block/zram/zram_drv.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 2ad0b5b..3920ee4 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -560,7 +560,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> }
>
> if (page_zero_filled(uncmem)) {
> - kunmap_atomic(user_mem);
> + if (user_mem)
> + kunmap_atomic(user_mem);
> /* Free memory associated with this sector now. */
> bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
> zram_free_page(zram, index);
>
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] zram: avoid kunmap_atomic a NULL pointer
2014-10-30 6:20 [PATCH] zram: avoid kunmap_atomic a NULL pointer Weijie Yang
2014-10-30 13:13 ` Jerome Marchand
@ 2014-10-31 13:46 ` Sergey Senozhatsky
1 sibling, 0 replies; 3+ messages in thread
From: Sergey Senozhatsky @ 2014-10-31 13:46 UTC (permalink / raw)
To: Weijie Yang
Cc: 'Minchan Kim', 'Andrew Morton',
'Sergey Senozhatsky', 'Dan Streetman',
'Nitin Gupta', 'Weijie Yang', 'Linux-MM',
'linux-kernel'
On (10/30/14 14:20), Weijie Yang wrote:
> zram could kunmap_atomic a NULL pointer in a rare situation:
> a zram page become a full-zeroed page after a partial write io.
> The current code doesn't handle this case and kunmap_atomic a
> NULL porinter, which panic the kernel.
>
> This patch fixes this issue.
>
> Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
thank you, Weijie.
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
-ss
> ---
> drivers/block/zram/zram_drv.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 2ad0b5b..3920ee4 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -560,7 +560,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> }
>
> if (page_zero_filled(uncmem)) {
> - kunmap_atomic(user_mem);
> + if (user_mem)
> + kunmap_atomic(user_mem);
> /* Free memory associated with this sector now. */
> bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
> zram_free_page(zram, index);
> --
> 1.7.0.4
>
>
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2014-10-30 13:13 ` Jerome Marchand
2014-10-31 13:46 ` Sergey Senozhatsky
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