On Thu 23-08-12 17:08:46, Glauber Costa wrote: > When we want to duplicate a new process, dup_task_struct() will undergo > a series of allocations. If alloc_thread_info_node() fails, we call > free_task_struct() and return. > > This seems right, but it is not. free_task_struct() will not only free > the task struct from the kmem_cache, but will also call > arch_release_task_struct(). The problem is that this function is > supposed to undo whatever arch-specific work done by > arch_dup_task_struct(), that is not yet called at this point. The > particular problem I ran accross was that in x86, we will arrive at > fpu_free() without having ever allocated it. > > This code is very ancient, and according to git, it is there since the > pre-git era. But forks don't fail that often, so that made it well > hidden. > > Signed-off-by: Glauber Costa <[email protected]> > Reported-by: Frederic Weisbecker <[email protected]> > --- > kernel/fork.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index 152d023..b397435 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -299,7 +299,7 @@ static struct task_struct *dup_task_struct(struct > task_struct *orig) > > ti = alloc_thread_info_node(tsk, node); > if (!ti) { > - free_task_struct(tsk); > + kmem_cache_free(task_struct_cachep, tsk);
What about ia64 (or !CONFIG_ARCH_THREAD_INFO_ALLOCATOR in general) which doesn't allocate thread_info at all? > return NULL; > } > > -- > 1.7.11.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
