Messages in this thread Patch in this message | | | From | Mike Rapoport <> | Subject | [PATCH] sched: fix build with GCC_PLUGIN_RANDSTRUCT | Date | Sat, 20 Jun 2020 13:41:36 +0300 |
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From: Mike Rapoport <rppt@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 <rppt@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
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