From 93a4b36ef3cf4ce5e6a7e7a7686181de76e246a1 Mon Sep 17 00:00:00 2001 From: Nirbhay Sharma Date: Fri, 3 Oct 2025 17:15:55 +0530 Subject: cgroup: Fix seqcount lockdep assertion in cgroup freezer MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The commit afa3701c0e45 ("cgroup: cgroup.stat.local time accounting") introduced a seqcount to track freeze timing but initialized it as a plain seqcount_t using seqcount_init(). However, the write-side critical section in cgroup_do_freeze() holds the css_set_lock spinlock while calling write_seqcount_begin(). On PREEMPT_RT kernels, spinlocks do not disable preemption, causing the lockdep assertion for a plain seqcount_t, which checks for preemption being disabled, to fail. This triggers the following warning: WARNING: CPU: 0 PID: 9692 at include/linux/seqlock.h:221 Fix this by changing the type to seqcount_spinlock_t and initializing it with seqcount_spinlock_init() to associate css_set_lock with the seqcount. This allows lockdep to correctly validate that the spinlock is held during write operations, resolving the assertion failure on all kernel configurations. Reported-by: syzbot+27a2519eb4dad86d0156@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=27a2519eb4dad86d0156 Fixes: afa3701c0e45 ("cgroup: cgroup.stat.local time accounting") Signed-off-by: Nirbhay Sharma Link: https://lore.kernel.org/r/20251002165510.KtY3IT--@linutronix.de/ Acked-by: Michal Koutný Signed-off-by: Tejun Heo --- include/linux/cgroup-defs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 93318fce31f3..b760a3c470a5 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -452,7 +452,7 @@ struct cgroup_freezer_state { int nr_frozen_tasks; /* Freeze time data consistency protection */ - seqcount_t freeze_seq; + seqcount_spinlock_t freeze_seq; /* * Most recent time the cgroup was requested to freeze. -- cgit v1.2.3 From 0fbbcab7f9082cdc233da5e5e353f69830f11956 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 17 Oct 2025 00:07:42 -0700 Subject: cgroup/misc: fix misc_res_type kernel-doc warning Format the kernel-doc for SCALE_HW_CALIB_INVALID correctly to avoid a kernel-doc warning: Warning: include/linux/misc_cgroup.h:26 Enum value 'MISC_CG_RES_TDX' not described in enum 'misc_res_type' Fixes: 7c035bea9407 ("KVM: TDX: Register TDX host key IDs to cgroup misc controller") Signed-off-by: Randy Dunlap Signed-off-by: Tejun Heo --- include/linux/misc_cgroup.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h index 71cf5bfc6349..0cb36a3ffc47 100644 --- a/include/linux/misc_cgroup.h +++ b/include/linux/misc_cgroup.h @@ -19,7 +19,7 @@ enum misc_res_type { MISC_CG_RES_SEV_ES, #endif #ifdef CONFIG_INTEL_TDX_HOST - /* Intel TDX HKIDs resource */ + /** @MISC_CG_RES_TDX: Intel TDX HKIDs resource */ MISC_CG_RES_TDX, #endif /** @MISC_CG_RES_TYPES: count of enum misc_res_type constants */ -- cgit v1.2.3