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SubjectRe: [PATCH v5 2/2] writeback, cgroup: release dying cgwbs by switching attached inodes
On Fri, May 28, 2021 at 10:58:04AM +0800, Ming Lei wrote:
> On Wed, May 26, 2021 at 03:25:57PM -0700, Roman Gushchin wrote:
> > Asynchronously try to release dying cgwbs by switching clean attached
> > inodes to the bdi's wb. It helps to get rid of per-cgroup writeback
> > structures themselves and of pinned memory and block cgroups, which
> > are way larger structures (mostly due to large per-cpu statistics
> > data). It helps to prevent memory waste and different scalability
> > problems caused by large piles of dying cgroups.
> >
> > A cgwb cleanup operation can fail due to different reasons (e.g. the
> > cgwb has in-glight/pending io, an attached inode is locked or isn't
> > clean, etc). In this case the next scheduled cleanup will make a new
> > attempt. An attempt is made each time a new cgwb is offlined (in other
> > words a memcg and/or a blkcg is deleted by a user). In the future an
> > additional attempt scheduled by a timer can be implemented.
> >
> > Signed-off-by: Roman Gushchin <guro@fb.com>
> > ---
> > fs/fs-writeback.c | 35 ++++++++++++++++++
> > include/linux/backing-dev-defs.h | 1 +
> > include/linux/writeback.h | 1 +
> > mm/backing-dev.c | 61 ++++++++++++++++++++++++++++++--
> > 4 files changed, 96 insertions(+), 2 deletions(-)
> >
>
> Hello Roman,
>
> The following kernel panic is triggered by this patch:

Hello Ming!

Thank you for the report and for trying my patches!
I think I know what it is and will fix in the next version.

Thanks!

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