| Message ID | 20210421124340.301916-1-seth.forshee@canonical.com |
|---|---|
| Headers | show |
| Series | Fix disk hot removal regression in s390x under kvm | expand |
On Wed, Apr 21, 2021 at 9:44 AM Seth Forshee <seth.forshee@canonical.com> wrote: > > BugLink: https://bugs.launchpad.net/bugs/1925211 > > [Impact] > > Hot removal of disks under kvm on s390 does not result in the kernel > removing the block device, which can lead to hung tasks and other > issues. > > [Fix] > > A bisect identified commit 8cc0dcfdc1c0 "s390/cio: remove pm support > from ccw bus driver" as introducing the regression. Reverting this patch > fixed the problem in testing. > > [Test Plan] > > See steps to reproduce the bug in the original description below. To > test, execute these steps and confirm that the block device gets removed > as expected. > > [Where problems could occur] > > The fix is a revert of the changes which introduced this regression. The > original commit was a removal of supposedly unused code, but it seems a > mistake was made in the logic around unregistering of disks. Reverting > the changes could have potential to introduce bugs related to other virt > devices, especially if it interacts badly with subsequent driver > changes. However, the patch reverted cleanly, and reverting restores the > code to the state which has been working well in previous kernels and > seems like the lowest risk option until a proper fix is available > upstream. > Thanks Seth, LGTM: Acked-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
On 21/04/2021 13:43, Seth Forshee wrote: > BugLink: https://bugs.launchpad.net/bugs/1925211 > > [Impact] > > Hot removal of disks under kvm on s390 does not result in the kernel > removing the block device, which can lead to hung tasks and other > issues. > > [Fix] > > A bisect identified commit 8cc0dcfdc1c0 "s390/cio: remove pm support > from ccw bus driver" as introducing the regression. Reverting this patch > fixed the problem in testing. > > [Test Plan] > > See steps to reproduce the bug in the original description below. To > test, execute these steps and confirm that the block device gets removed > as expected. > > [Where problems could occur] > > The fix is a revert of the changes which introduced this regression. The > original commit was a removal of supposedly unused code, but it seems a > mistake was made in the logic around unregistering of disks. Reverting > the changes could have potential to introduce bugs related to other virt > devices, especially if it interacts badly with subsequent driver > changes. However, the patch reverted cleanly, and reverting restores the > code to the state which has been working well in previous kernels and > seems like the lowest risk option until a proper fix is available > upstream. > > --- > > Seth Forshee (1): > UBUNTU: SAUCE: Revert "s390/cio: remove pm support from ccw bus > driver" > > arch/s390/include/asm/ccwdev.h | 10 ++ > drivers/s390/cio/cmf.c | 5 + > drivers/s390/cio/device.c | 247 ++++++++++++++++++++++++++++++++- > drivers/s390/cio/device.h | 1 + > drivers/s390/cio/device_fsm.c | 6 + > drivers/s390/cio/io_sch.h | 1 + > 6 files changed, 268 insertions(+), 2 deletions(-) > > Yep, seems good to me. Acked-by: Colin Ian King <colin.king@canonical.com>
On 21.04.21 14:43, Seth Forshee wrote: > BugLink: https://bugs.launchpad.net/bugs/1925211 > > [Impact] > > Hot removal of disks under kvm on s390 does not result in the kernel > removing the block device, which can lead to hung tasks and other > issues. > > [Fix] > > A bisect identified commit 8cc0dcfdc1c0 "s390/cio: remove pm support > from ccw bus driver" as introducing the regression. Reverting this patch > fixed the problem in testing. > > [Test Plan] > > See steps to reproduce the bug in the original description below. To > test, execute these steps and confirm that the block device gets removed > as expected. > > [Where problems could occur] > > The fix is a revert of the changes which introduced this regression. The > original commit was a removal of supposedly unused code, but it seems a > mistake was made in the logic around unregistering of disks. Reverting > the changes could have potential to introduce bugs related to other virt > devices, especially if it interacts badly with subsequent driver > changes. However, the patch reverted cleanly, and reverting restores the > code to the state which has been working well in previous kernels and > seems like the lowest risk option until a proper fix is available > upstream. > > --- > > Seth Forshee (1): > UBUNTU: SAUCE: Revert "s390/cio: remove pm support from ccw bus > driver" > > arch/s390/include/asm/ccwdev.h | 10 ++ > drivers/s390/cio/cmf.c | 5 + > drivers/s390/cio/device.c | 247 ++++++++++++++++++++++++++++++++- > drivers/s390/cio/device.h | 1 + > drivers/s390/cio/device_fsm.c | 6 + > drivers/s390/cio/io_sch.h | 1 + > 6 files changed, 268 insertions(+), 2 deletions(-) > > Applied to hirsute:linux/master-next. Thanks. -Stefan
BugLink: https://bugs.launchpad.net/bugs/1925211 [Impact] Hot removal of disks under kvm on s390 does not result in the kernel removing the block device, which can lead to hung tasks and other issues. [Fix] A bisect identified commit 8cc0dcfdc1c0 "s390/cio: remove pm support from ccw bus driver" as introducing the regression. Reverting this patch fixed the problem in testing. [Test Plan] See steps to reproduce the bug in the original description below. To test, execute these steps and confirm that the block device gets removed as expected. [Where problems could occur] The fix is a revert of the changes which introduced this regression. The original commit was a removal of supposedly unused code, but it seems a mistake was made in the logic around unregistering of disks. Reverting the changes could have potential to introduce bugs related to other virt devices, especially if it interacts badly with subsequent driver changes. However, the patch reverted cleanly, and reverting restores the code to the state which has been working well in previous kernels and seems like the lowest risk option until a proper fix is available upstream. --- Seth Forshee (1): UBUNTU: SAUCE: Revert "s390/cio: remove pm support from ccw bus driver" arch/s390/include/asm/ccwdev.h | 10 ++ drivers/s390/cio/cmf.c | 5 + drivers/s390/cio/device.c | 247 ++++++++++++++++++++++++++++++++- drivers/s390/cio/device.h | 1 + drivers/s390/cio/device_fsm.c | 6 + drivers/s390/cio/io_sch.h | 1 + 6 files changed, 268 insertions(+), 2 deletions(-)