ping?
On Sat, Jun 20, 2020 at 01:41:36PM +0300, Mike Rapoport wrote:
> From: Mike Rapoport <r...@linux.ibm.com>
>
> Since the commit a148866489fb ("sched: Replace rq::wake_list")
> task_struct and CSD_TYPE_TTWU objects can be on the same queue and this
> requires that have "layout similar enough".
>
> This assumption is broken when CONFIG_GCC_PLUGIN_RANDSTRUCT is enabled:
>
> CHK include/generated/compile.h
> CC kernel/smp.o
> In file included from arch/x86/include/asm/atomic.h:5,
> from include/linux/atomic.h:7,
> from include/linux/llist.h:51,
> from include/linux/irq_work.h:5,
> from kernel/smp.c:10:
> kernel/smp.c: In function ‘smp_init’:
> include/linux/compiler.h:392:38: error: call to ‘__compiletime_assert_157’
> declared with attribute error: BUILD_BUG_ON failed: offsetof(struct
> task_struct, wake_entry_type) - offsetof(struct task_struct, wake_entry) !=
> offsetof(struct __call_single_data, flags) - offsetof(struct
> __call_single_data, llist)
> 392 | _compiletime_assert(condition, msg, __compiletime_assert_,
> __COUNTER__)
> | ^
> include/linux/compiler.h:373:4: note: in definition of macro
> ‘__compiletime_assert’
> 373 | prefix ## suffix(); \
> | ^~~~~~
> include/linux/compiler.h:392:2: note: in expansion of macro
> ‘_compiletime_assert’
> 392 | _compiletime_assert(condition, msg, __compiletime_assert_,
> __COUNTER__)
> | ^~~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:39:37: note: in expansion of macro
> ‘compiletime_assert’
> 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> | ^~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:50:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
> 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
> | ^~~~~~~~~~~~~~~~
> kernel/smp.c:687:2: note: in expansion of macro ‘BUILD_BUG_ON’
> 687 | BUILD_BUG_ON(offsetof(struct task_struct, wake_entry_type) -
> offsetof(struct task_struct, wake_entry) !=
> | ^~~~~~~~~~~~
> make[2]: *** [scripts/Makefile.build:280: kernel/smp.o] Error 1
> make[1]: *** [Makefile:1764: kernel] Error 2
> make[1]: *** Waiting for unfinished jobs....
> make[1]: Leaving directory '/home/mike/build/kernel'
> make: *** [Makefile:185: __sub-make] Error 2
>
> Move 'wake_entry' and 'wake_entry_type' fiels of task_struct out of the
> randomized fields to keep their layout intact.
>
> Signed-off-by: Mike Rapoport <r...@linux.ibm.com>
> ---
> include/linux/sched.h | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index b62e6aaf28f0..c885573669ac 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -641,6 +641,15 @@ struct task_struct {
> /* -1 unrunnable, 0 runnable, >0 stopped: */
> volatile long state;
>
> + /*
> + * The layout of these fields must match the layout CSD_TYPE_TTWU
> + * so they can be on the same the @call_single_queue
> + */
> +#ifdef CONFIG_SMP
> + struct llist_node wake_entry;
> + unsigned int wake_entry_type;
> +#endif
> +
> /*
> * This begins the randomizable portion of task_struct. Only
> * scheduling-critical items should be added above here.
> @@ -654,8 +663,6 @@ struct task_struct {
> unsigned int ptrace;
>
> #ifdef CONFIG_SMP
> - struct llist_node wake_entry;
> - unsigned int wake_entry_type;
> int on_cpu;
> #ifdef CONFIG_THREAD_INFO_IN_TASK
> /* Current CPU: */
> --
> 2.25.4
>
--
Sincerely yours,
Mike.
