Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
md/raid1,raid10: don’t ignore IO flags
If blk-wbt is enabled by default, it’s found that raid write performance is quite bad because all IO are throttled by wbt of underlying disks, due to flag REQ_IDLE is ignored. And turns out this behaviour exist since blk-wbt is introduced.
Other than REQ_IDLE, other flags should not be ignored as well, for example REQ_META can be set for filesystems, clearing it can cause priority reverse problems; And REQ_NOWAIT should not be cleared as well, because io will wait instead of failing directly in underlying disks.
Fix those problems by keep IO flags from master bio.
Fises: f51d46d0e7cb (“md: add support for REQ_NOWAIT”)
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 6 ELS , CloudLinux 7 ELS , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 2.6.32 (+16 more)
In the Linux kernel, the following vulnerability has been resolved:
md/raid1,raid10: don’t ignore IO flags
If blk-wbt is enabled by default, it’s found that raid write performance is quite bad because all IO are throttled by wbt of underlying disks, due to flag REQ_IDLE is ignored. And turns out this behaviour exist since blk-wbt is introduced.
Other than REQ_IDLE, other flags should not be ignored as well, for example REQ_META can be set for filesystems, clearing it can cause priority reverse problems; And REQ_NOWAIT should not be cleared as well, because io will wait instead of failing directly in underlying disks.
Fix those problems by keep IO flags from master bio.
Fises: f51d46d0e7cb (“md: add support for REQ_NOWAIT”)