Recently we ran into a oom issue, kernel panic due to no killable process.
The dmesg shows huge unreclaimable slabs used almost 100% memory, but kdump
doesn't capture vmcore due to some reason.
So, it may sound better to capture unreclaimable slab info in oom message when
kernel panic to aid trouble shooting and cover the corner case.
Since kernel already panic, so capturing more information sounds worthy and
doesn't bother normal oom killer.
With the patchset, tools/vm/slabinfo has a new option, "-U", to show
unreclaimable slab only.
And, oom will print all non zero (num_objs * size != 0) unreclaimable slabs in
oom killer message.
For details, please see the commit log for each commit.
Changelog v10 —> v11:
* Fixed compile failure reported by 0-DAY test. Andrew, please replace all of
them.
* Adopted the suggestion from Michal to remove memset()
* Added Acked-By from Michal
Changelog v9 —> v10:
* Adopted the suggestion from Michal to just dump unreclaimable slab stats when
!is_memcg_oom
* Adopted the suggestion from Michal to print warning when unreclaimable slabs
dump can’t acquire the mutex
Changelog v8 —> v9:
* Adopted Tetsuo’s suggestion to protect global slab list traverse with
mutex_trylock() to prevent from sleeping. Without the mutex acquired
unreclaimable slbas will not be dumped.
* Adopted the suggestion from Christoph to dump CONFIG_SLABINFO since it is
pointless to keep it.
* Rebased to 4.13-rc3
Changelog v7 —> v8:
* Adopted Michal’s suggestion to dump unreclaim slab info when unreclaimable
slabs amount > total user memory. Not only in oom panic path.
Changelog v6 -> v7:
* Added unreclaim_slabs_oom_ratio proc knob, unreclaimable slabs info will be
dumped when unreclaimable slabs amount : all user memory > the ratio
Changelog v5 —> v6:
* Fixed a checkpatch.pl warning for patch #2
Changelog v4 —> v5:
* Solved the comments from David
* Build test SLABINFO = n
Changelog v3 —> v4:
* Solved the comments from David
* Added David’s Acked-by in patch 1
Changelog v2 —> v3:
* Show used size and total size of each kmem cache per David’s comment
Changelog v1 —> v2:
* Removed the original patch 1 (“mm: slab: output reclaimable flag in
/proc/slabinfo”) since Christoph suggested it might break the compatibility and
/proc/slabinfo is legacy
* Added Christoph’s Acked-by
* Removed acquiring slab_mutex per Tetsuo’s comment
Yang Shi (3):
tools: slabinfo: add "-U" option to show unreclaimable slabs only
mm: slabinfo: dump CONFIG_SLABINFO
mm: oom: show unreclaimable slab info when unreclaimable slabs > user
memory
init/Kconfig | 6 ------
mm/memcontrol.c | 2 +-
mm/oom_kill.c | 27 +++++++++++++++++++++++++--
mm/slab.c | 2 --
mm/slab.h | 8 ++++++++
mm/slab_common.c | 41 +++++++++++++++++++++++++++++++++++++----
mm/slub.c | 4 ++--
tools/vm/slabinfo.c | 11 ++++++++++-
8 files changed, 83 insertions(+), 18 deletions(-)
