Messages in this thread | | | Date | Thu, 23 Aug 2012 16:38:50 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] fork: fix oops after fork failure |
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On Thu 23-08-12 16:33:12, Michal Hocko wrote: > 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 <glommer@parallels.com> > > Reported-by: Frederic Weisbecker <fweisbec@redhat.com> > > --- > > 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?
Hit send button too fast. Should read (or CONFIG_ARCH_THREAD_INFO_ALLOCATOR) ia64 will not fail obviously and there is no other arch which would define own thread infor allocators but there might be some in future. -- Michal Hocko SUSE Labs
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