| Message ID | 169335047228.3523635.3342369338633870707.stgit@frogsfrogsfrogs (mailing list archive) |
|---|---|
| Headers | show |
| Series | fstests: fix cpu hotplug mess | expand |
On Tue, Aug 29, 2023 at 04:07:52PM -0700, Darrick J. Wong wrote: > Hi all, > > Ritesh and Eric separately reported crashes in XFS's hook function for > CPU hot remove if the remove event races with a filesystem being > mounted. I also noticed via generic/650 that once in a while the log > will shut down over an apparent overrun of a transaction reservation; > this turned out to be due to CIL percpu list aggregation failing to pick > up the percpu list items from a dying CPU. > > Either way, the solution here is to eliminate the need for a CPU dying > hook by using a private cpumask to track which CPUs have added to their > percpu lists directly, and iterating with that mask. This fixes the log > problems and (I think) solves a theoretical UAF bug in the inodegc code > too. > > v2: fix a few put_cpu uses, add necessary memory barriers, and use > atomic cpumask operations > > If you're going to start using this code, I strongly recommend pulling > from my git trees, which are linked below. > > This has been running on the djcloud for months with no problems. Enjoy! > Comments and questions are, as always, welcome. These changes look good. Reviewed-by: Dave Chinner <dchinner@redhat.com>
Hi all, Ritesh and Eric separately reported crashes in XFS's hook function for CPU hot remove if the remove event races with a filesystem being mounted. I also noticed via generic/650 that once in a while the log will shut down over an apparent overrun of a transaction reservation; this turned out to be due to CIL percpu list aggregation failing to pick up the percpu list items from a dying CPU. Either way, the solution here is to eliminate the need for a CPU dying hook by using a private cpumask to track which CPUs have added to their percpu lists directly, and iterating with that mask. This fixes the log problems and (I think) solves a theoretical UAF bug in the inodegc code too. v2: fix a few put_cpu uses, add necessary memory barriers, and use atomic cpumask operations If you're going to start using this code, I strongly recommend pulling from my git trees, which are linked below. This has been running on the djcloud for months with no problems. Enjoy! Comments and questions are, as always, welcome. --D fstests git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=fix-percpu-lists --- tests/generic/650 | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)