Commit-ID: d3d03d4fc5b1bec3a579112de170a9676e9d97cb Gitweb: http://git.kernel.org/tip/d3d03d4fc5b1bec3a579112de170a9676e9d97cb Author: Yong Zhang <yong.zhang0@xxxxxxxxx> AuthorDate: Wed, 9 Nov 2011 16:04:51 +0800 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Tue, 6 Dec 2011 08:16:51 +0100 lockdep, kmemcheck: Annotate ->lock in lockdep_init_map() Since commit f59de89 ("lockdep: Clear whole lockdep_map on initialization"), lockdep_init_map() will clear all the struct. But it will break lock_set_class()/lock_set_subclass(). A typical race condition is like below: CPU A CPU B lock_set_subclass(lockA); lock_set_class(lockA); lockdep_init_map(lockA); /* lockA->name is cleared */ memset(lockA); __lock_acquire(lockA); /* lockA->class_cache[] is cleared */ register_lock_class(lockA); look_up_lock_class(lockA); WARN_ON_ONCE(class->name != lock->name); lock->name = name; So restore to what we have done before commit f59de89 but annotate ->lock with kmemcheck_mark_initialized() to suppress the kmemcheck warning reported in commit f59de89. Reported-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Reported-by: Borislav Petkov <bp@xxxxxxxxx> Suggested-by: Vegard Nossum <vegard.nossum@xxxxxxxxx> Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Link: http://lkml.kernel.org/r/20111109080451.GB8124@zhy Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/lockdep.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index a2ab30c..54cc0dc 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -44,6 +44,7 @@ #include <linux/stringify.h> #include <linux/bitops.h> #include <linux/gfp.h> +#include <linux/kmemcheck.h> #include <asm/sections.h> @@ -2950,7 +2951,12 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, void lockdep_init_map(struct lockdep_map *lock, const char *name, struct lock_class_key *key, int subclass) { - memset(lock, 0, sizeof(*lock)); + int i; + + kmemcheck_mark_initialized(lock, sizeof(*lock)); + + for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) + lock->class_cache[i] = NULL; #ifdef CONFIG_LOCK_STAT lock->cpu = raw_smp_processor_id(); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html