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.
Signed-off-by: Glauber Costa <glom...@parallels.com>
Reported-by: Frederic Weisbecker <fweis...@redhat.com>
CC: Thomas Gleixner <t...@linutronix.de>
CC: Tony Luck <tony.l...@intel.com>
CC: Fenghua Yu <fenghua...@intel.com>
---
arch/ia64/include/asm/thread_info.h | 2 +-
kernel/fork.c | 9 +++++++--
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/ia64/include/asm/thread_info.h
b/arch/ia64/include/asm/thread_info.h
index f7ee853..62452bd 100644
--- a/arch/ia64/include/asm/thread_info.h
+++ b/arch/ia64/include/asm/thread_info.h
@@ -90,7 +90,7 @@ struct thread_info {
\
ret;
\
})
-#define free_task_struct(tsk) free_pages((unsigned long) (tsk),
KERNEL_STACK_SIZE_ORDER)
+#define __free_task_struct(tsk) free_pages((unsigned long) (tsk),
KERNEL_STACK_SIZE_ORDER)
#endif /* !__ASSEMBLY */
diff --git a/kernel/fork.c b/kernel/fork.c
index 152d023..76acb1a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -124,10 +124,15 @@ static inline struct task_struct
*alloc_task_struct_node(int node)
void __weak arch_release_task_struct(struct task_struct *tsk) { }
+static inline void __free_task_struct(struct task_struct *tsk)
+{
+ kmem_cache_free(task_struct_cachep, tsk);
+}
+
static inline void free_task_struct(struct task_struct *tsk)
{
arch_release_task_struct(tsk);
- kmem_cache_free(task_struct_cachep, tsk);
+ __free_task_struct(tsk);
}
#endif
@@ -299,7 +304,7 @@ static struct task_struct *dup_task_struct(struct
task_struct *orig)
ti = alloc_thread_info_node(tsk, node);
if (!ti) {
- free_task_struct(tsk);
+ __free_task_struct(tsk);
return NULL;
}
--
1.7.11.4
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