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dm: fix infinite loop in dm_blk_do_report_zones() - #1468
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If the device underlying a zoned target is removed, its capacity is set to 0 and blkdev_report_zones() returns 0 without reporting any zones. The mapped device keeps its old capacity, so args->zone_idx and args->next_sector never advance and dm_blk_do_report_zones() loops forever. On non-preemptible kernels this causes soft lockups and RCU stalls. The following sequence of commands triggers the hang: modprobe scsi_debug zbc=managed dev_size_mb=1024 zone_size_mb=64 udevadm settle echo '0 2097152 linear /dev/sda 0' | dmsetup create lin echo 1 > /sys/block/sda/device/delete blkzone report -o 0 -c 1 /dev/mapper/lin Fix this by returning -EIO when a target reports no zones. The target always maps args->next_sector, so a zero return means the underlying device no longer covers that sector. Fixes: d410035 ("block: rework zone reporting") Cc: stable@vger.kernel.org Signed-off-by: Mark Bundschuh <mkbund@amazon.com>
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Upstream branch: c03c1a1 |
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Pull request for series with
subject: dm: fix infinite loop in dm_blk_do_report_zones()
version: 1
url: https://patchwork.kernel.org/series/1189208/