4.20-stable review patch. If anyone has any objections, please let me know.
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From: Minchan Kim minchan@kernel.org
commit 5547932dc67a48713eece4fa4703bfdf0cfcb818 upstream.
If blkdev_get fails, we shouldn't do blkdev_put. Otherwise, kernel emits below log. This patch fixes it.
WARNING: CPU: 0 PID: 1893 at fs/block_dev.c:1828 blkdev_put+0x105/0x120 Modules linked in: CPU: 0 PID: 1893 Comm: swapoff Not tainted 4.19.0+ #453 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 RIP: 0010:blkdev_put+0x105/0x120 Call Trace: __x64_sys_swapoff+0x46d/0x490 do_syscall_64+0x5a/0x190 entry_SYSCALL_64_after_hwframe+0x49/0xbe irq event stamp: 4466 hardirqs last enabled at (4465): __free_pages_ok+0x1e3/0x490 hardirqs last disabled at (4466): trace_hardirqs_off_thunk+0x1a/0x1c softirqs last enabled at (3420): __do_softirq+0x333/0x446 softirqs last disabled at (3407): irq_exit+0xd1/0xe0
Link: http://lkml.kernel.org/r/20181127055429.251614-3-minchan@kernel.org Signed-off-by: Minchan Kim minchan@kernel.org Reviewed-by: Sergey Senozhatsky sergey.senozhatsky@gmail.com Reviewed-by: Joey Pabalinas joeypabalinas@gmail.com Cc: stable@vger.kernel.org [4.14+] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/zram/zram_drv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -382,8 +382,10 @@ static ssize_t backing_dev_store(struct
bdev = bdgrab(I_BDEV(inode)); err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram); - if (err < 0) + if (err < 0) { + bdev = NULL; goto out; + }
nr_pages = i_size_read(inode) >> PAGE_SHIFT; bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);