James Morse 45c2e30bbd x86/resctrl: Fix rdtgroup_mkdir()'s unlocked use of kernfs_node::name ... Since 741c10b096 ("kernfs: Use RCU to access kernfs_node::name.") a helper rdt_kn_name() that checks that rdtgroup_mutex is held has been used for all accesses to the kernfs node name. rdtgroup_mkdir() uses the name to determine if a valid monitor group is being created by checking the parent name is "mon_groups". This is done without holding rdtgroup_mutex, and now triggers the following warning: | WARNING: suspicious RCU usage | 6.15.0-rc1 #4465 Tainted: G E | ----------------------------- | arch/x86/kernel/cpu/resctrl/internal.h:408 suspicious rcu_dereference_check() usage! [...] | Call Trace: | <TASK> | dump_stack_lvl | lockdep_rcu_suspicious.cold | is_mon_groups | rdtgroup_mkdir | kernfs_iop_mkdir | vfs_mkdir | do_mkdirat | __x64_sys_mkdir | do_syscall_64 | entry_SYSCALL_64_after_hwframe Creating a control or monitor group calls mkdir_rdt_prepare(), which uses rdtgroup_kn_lock_live() to take the rdtgroup_mutex. To avoid taking and dropping the lock, move the check for the monitor group name and position into mkdir_rdt_prepare() so that it occurs under rdtgroup_mutex. Hoist is_mon_groups() earlier in the file. [ bp: Massage. ] Fixes: 741c10b096 ("kernfs: Use RCU to access kernfs_node::name.") Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20250407124637.2433230-1-james.morse@arm.com		2025-04-09 11:35:08 +02:00
..
Makefile	x86/resctrl: Allow an architecture to disable pseudo lock	2025-03-12 12:24:25 +01:00
core.c	x86/resctrl: Move get_{mon,ctrl}_domain_from_cpu() to live with their callers	2025-03-12 12:24:58 +01:00
ctrlmondata.c	x86/resctrl: Move get_config_index() to a header	2025-03-12 12:24:54 +01:00
internal.h	Driver core updates for 6.15-rc1	2025-04-01 11:02:03 -07:00
monitor.c	x86/resctrl: Move get_{mon,ctrl}_domain_from_cpu() to live with their callers	2025-03-12 12:24:58 +01:00
pseudo_lock.c	Driver core updates for 6.15-rc1	2025-04-01 11:02:03 -07:00
rdtgroup.c	x86/resctrl: Fix rdtgroup_mkdir()'s unlocked use of kernfs_node::name	2025-04-09 11:35:08 +02:00
trace.h	x86/resctrl: Add tracepoint for llc_occupancy tracking	2024-04-24 14:24:48 +02:00