[merged] zram-avoid-kunmap_atomic-a-null-pointer.patch removed from -mm tree

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The patch titled
     Subject: zram: avoid kunmap_atomic() of a NULL pointer
has been removed from the -mm tree.  Its filename was
     zram-avoid-kunmap_atomic-a-null-pointer.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Subject: zram: avoid kunmap_atomic() of a NULL pointer

zram could kunmap_atomic() a NULL pointer in a rare situation: a zram page
becomes a full-zeroed page after a partial write io.  The current code
doesn't handle this case and performs kunmap_atomic() on a NULL pointer,
which panics the kernel.

This patch fixes this issue.

Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Weijie Yang <weijie.yang.kh@xxxxxxxxx>
Acked-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 drivers/block/zram/zram_drv.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -puN drivers/block/zram/zram_drv.c~zram-avoid-kunmap_atomic-a-null-pointer drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-avoid-kunmap_atomic-a-null-pointer
+++ a/drivers/block/zram/zram_drv.c
@@ -560,7 +560,8 @@ static int zram_bvec_write(struct zram *
 	}
 
 	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);
_

Patches currently in -mm which might be from weijie.yang@xxxxxxxxxxx are

mm-page_isolation-check-pfn-validity-before-access.patch
mm-mincore-add-hwpoison-page-handle.patch
mm-mincore-add-hwpoison-page-handle-checkpatch-fixes.patch

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