<div dir="ltr">Understood, thank you Stefan</div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jun 29, 2021 at 3:26 PM Stefan Bader <<a href="mailto:stefan.bader@canonical.com">stefan.bader@canonical.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 28.06.21 11:37, Gerald Yang wrote: > Hi Stefan, > > I checked and also tried to backport these commits: > git log --oneline --grep "Fixes: 39d42fa96ba1" > c87a95dc28b1 dm crypt: defer decryption to a tasklet if interrupts disabled > 8e14f610159d dm crypt: do not call bio_endio() from the dm-crypt tasklet > d68b29584c25 dm crypt: use GFP_ATOMIC when allocating crypto requests from softirq > 8abec36d1274 dm crypt: do not wait for backlogged crypto request completion in > softirq > 4a5caa4af0df dm crypt: document new no_workqueue flags > > But it failed to build the kernel, I found there are more dependencies need to > be backported > Take focal kernel (5.4) for instance, the build error is: > /home/ubuntu/focal/drivers/md/dm-crypt.c:2768:8: error: ‘dm_report_zones_cb’ > undeclared (first use in this function); did you mean ‘dm_report_zones_fn’? > 2768 | dm_report_zones_cb, args); > > This function "dm_report_zones_cb" was introduced in this commit in 5.5 kernel: > git log -L :dm_report_zones_cb:drivers/md/dm.c > commit d41003513e61dd9d4974cb441d30b63650b85654 > git describe --contains d41003513e61dd9d4974cb441d30b63650b85654 > v5.5-rc1~199^2~1 > > It reworked "zone reporting" > d41003513e61 block: rework zone reporting > > And modify some other files in block layer > drivers/md/dm-flakey.c > drivers/md/dm-linear.c > drivers/scsi/sd.h > fs/f2fs/super.c > include/linux/device-mapper.h > block/blk-zoned.c > drivers/block/null_blk.h > drivers/block/null_blk_zoned.c > drivers/md/dm-zoned-metadata.c > drivers/md/dm.c > drivers/scsi/sd_zbc.c > include/linux/blkdev.h > > I think it could get more dependencies involved for backporting this commit > > And the original commit I wanted to backport > (39d42fa96ba1b7d2544db3f8ed5da8fb0d5cb877) > changes dm-crypt version from 1.19.0 to 1.22.0 for focal kernel (5.4) > > Because this is a request from our customer, I would like to ask for advice if > it's still proper to backport this one and all related commits? The amount of follow-up changes which were done upstream to a seemingly simple functional tweak suggest this change had more complications than even upstream anticipated. At some point we have to make a decision and for LTS release kernels this would be rather in favour of stability over feature backports. Even more so the older a release is (I would acutally never consider feature changes to Bionic anymore). Groovy nears its end of life and I assume Hirsute already has this. And somehow the errors of the Focal 5.4 backport sound like a lot of generic device-mapper infrastructure would have to be backported and that would put the stability of the kernel at risk. So I would rather point that customer at the hwe-5.11 kernel which is about to become the default hwe kernel for Focal. -Stefan > or it's better to wait for a newer hwe kernel that has this commit included? > > Thanks, > Gerald > > On Wed, May 19, 2021 at 3:26 PM Gerald Yang <<a href="mailto:gerald.yang@canonical.com" target="_blank">gerald.yang@canonical.com</a> > <mailto:<a href="mailto:gerald.yang@canonical.com" target="_blank">gerald.yang@canonical.com</a>>> wrote: > > Thanks Stefan, I will update the SRU with all related commits > > On Tue, May 18, 2021 at 2:42 PM Stefan Bader <<a href="mailto:stefan.bader@canonical.com" target="_blank">stefan.bader@canonical.com</a> > <mailto:<a href="mailto:stefan.bader@canonical.com" target="_blank">stefan.bader@canonical.com</a>>> wrote: > > On 18.05.21 04:56, Gerald Yang wrote: > > BugLink: <a href="https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1910976" rel="noreferrer" target="_blank">https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1910976</a> > <<a href="https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1910976" rel="noreferrer" target="_blank">https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1910976</a>> > > Above should be <a href="https://bugs.launchpad.net/bugs/1910976" rel="noreferrer" target="_blank">https://bugs.launchpad.net/bugs/1910976</a> > <<a href="https://bugs.launchpad.net/bugs/1910976" rel="noreferrer" target="_blank">https://bugs.launchpad.net/bugs/1910976</a>> but that could be done > when applying. However there seem to be multiple references to this patch > following its introduction upstream (see below). That does not sound > like just > picking this one patch is a good idea. > > -Stefan > > > > > === SRU Justification === > > [Impact] > > To get better performance for dm-crypt in some cases, bypass kcryptd > > workqueue can reduce the overhead in context switch between kworkers, > > cherry-pick commit 39d42fa96ba1b7d2544db3f8ed5da8fb0d5cb877 from mainline > > kernel, and bypass kcryptd workqueue is not enabled by default > > > > [Fix] > > Add flags to bypass kcryptd workqueue > > > > [Test] > > create dm-crypt and setup DM_CRYPT_NO_READ_WORKQUEUE and > > DM_CRYPT_NO_WRITE_WORKQUEUE, read/write data and run perf record to see > > if read/write to the encrypted device will bypass kcryptd workqueue > > > > [Regression Potential] > > Low, this feature is disabled by default, need to enable manually > > > > Ignat Korchagin (1): > > dm crypt: add flags to optionally bypass kcryptd workqueues > > > > drivers/md/dm-crypt.c | 50 ++++++++++++++++++++++++++++++++++++------- > > 1 file changed, 42 insertions(+), 8 deletions(-) > > > > > git log --oneline --grep "Fixes: 39d42fa96ba1" > c87a95dc28b1 dm crypt: defer decryption to a tasklet if interrupts disabled > 8e14f610159d dm crypt: do not call bio_endio() from the dm-crypt tasklet > d68b29584c25 dm crypt: use GFP_ATOMIC when allocating crypto requests > from softirq > 8abec36d1274 dm crypt: do not wait for backlogged crypto request > completion in > softirq > 4a5caa4af0df dm crypt: document new no_workqueue flags > </blockquote></div>