| Message ID | 169335040678.3522698.12786707653439539265.stgit@frogsfrogsfrogs (mailing list archive) |
|---|---|
| Headers | show |
| Series | xfs: fix cpu hotplug mess | expand |
On Tue, Aug 29, 2023 at 04:06:46PM -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 lightly tested with fstests. Enjoy! > Comments and questions are, as always, welcome. Series looks good. Removes a bunch of code and makes things more reliable, so what's not to like about it? 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 lightly tested with fstests. Enjoy! Comments and questions are, as always, welcome. --D kernel git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fix-percpu-lists-6.6 --- fs/xfs/xfs_icache.c | 78 ++++++++++++++-------------------------- fs/xfs/xfs_icache.h | 1 - fs/xfs/xfs_log_cil.c | 52 ++++++++------------------- fs/xfs/xfs_log_priv.h | 14 +++---- fs/xfs/xfs_mount.h | 7 ++-- fs/xfs/xfs_super.c | 86 +------------------------------------------- include/linux/cpuhotplug.h | 1 - 7 files changed, 56 insertions(+), 183 deletions(-)