Hi,
This started as a bug report by Hillf Danton and aims to access
kernfs_node::{name|parent} with RCU to avoid the lock during
kernfs_path_from_node().
I've split the individual fixes in separate patches (#1 to #4). I've
also split the ::parent and ::name RCU conversation into a single patch
(#5 and #6).
v3: https://lore.kernel.org/all/20241121175250.EJbI7VMb@xxxxxxxxxxxxx/
v2: https://lore.kernel.org/all/20241112155713.269214-1-bigeasy@xxxxxxxxxxxxx/
v1: https://lore.kernel.org/all/20241108222406.n5azgO98@xxxxxxxxxxxxx/
Sebastian
Sebastian Andrzej Siewior (6):
kernfs: Acquire kernfs_rwsem in kernfs_notify_workfn().
kernfs: Acquire kernfs_rwsem in kernfs_get_parent_dentry().
kernfs: Acquire kernfs_rwsem in kernfs_node_dentry().
kernfs: Don't re-lock kernfs_root::kernfs_rwsem in
kernfs_fop_readdir().
kernfs: Use RCU to access kernfs_node::parent.
kernfs: Use RCU to access kernfs_node::name.
arch/x86/kernel/cpu/resctrl/internal.h | 5 +
arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 14 +-
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 60 ++++---
fs/kernfs/dir.c | 203 ++++++++++++----------
fs/kernfs/file.c | 6 +-
fs/kernfs/kernfs-internal.h | 24 ++-
fs/kernfs/mount.c | 21 ++-
fs/kernfs/symlink.c | 30 ++--
fs/sysfs/dir.c | 2 +-
fs/sysfs/file.c | 24 ++-
include/linux/kernfs.h | 11 +-
kernel/cgroup/cgroup-v1.c | 2 +-
kernel/cgroup/cgroup.c | 16 +-
security/selinux/hooks.c | 7 +-
14 files changed, 263 insertions(+), 162 deletions(-)
--
2.47.2
