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Date: Thu, 30 Oct 2014 14:20:31 +0800 From: Weijie Yang <weijie.yang@...sung.com> To: 'Minchan Kim' <minchan@...nel.org> Cc: 'Andrew Morton' <akpm@...ux-foundation.org>, 'Sergey Senozhatsky' <sergey.senozhatsky@...il.com>, 'Dan Streetman' <ddstreet@...e.org>, 'Nitin Gupta' <ngupta@...are.org>, 'Weijie Yang' <weijie.yang.kh@...il.com>, 'Linux-MM' <linux-mm@...ck.org>, 'linux-kernel' <linux-kernel@...r.kernel.org> Subject: [PATCH] zram: avoid kunmap_atomic a NULL pointer 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@...sung.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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