From: Yong Zhang Date: Tue, 15 May 2012 13:53:56 +0800 Subject: [PATCH 170/342] mm: Protect activate_mm() by preempt_[disable&enable]_rt() Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=9c267b77756364bd7e03dfa8c35b44e8aac88a92 User preempt_*_rt instead of local_irq_*_rt or otherwise there will be warning on ARM like below: WARNING: at build/linux/kernel/smp.c:459 smp_call_function_many+0x98/0x264() Modules linked in: [] (unwind_backtrace+0x0/0xe4) from [] (warn_slowpath_common+0x4c/0x64) [] (warn_slowpath_common+0x4c/0x64) from [] (warn_slowpath_null+0x18/0x1c) [] (warn_slowpath_null+0x18/0x1c) from [](smp_call_function_many+0x98/0x264) [] (smp_call_function_many+0x98/0x264) from [] (smp_call_function+0x44/0x6c) [] (smp_call_function+0x44/0x6c) from [] (__new_context+0xbc/0x124) [] (__new_context+0xbc/0x124) from [] (flush_old_exec+0x460/0x5e4) [] (flush_old_exec+0x460/0x5e4) from [] (load_elf_binary+0x2e0/0x11ac) [] (load_elf_binary+0x2e0/0x11ac) from [] (search_binary_handler+0x94/0x2a4) [] (search_binary_handler+0x94/0x2a4) from [] (do_execve+0x254/0x364) [] (do_execve+0x254/0x364) from [] (sys_execve+0x34/0x54) [] (sys_execve+0x34/0x54) from [] (ret_fast_syscall+0x0/0x30) ---[ end trace 0000000000000002 ]--- The reason is that ARM need irq enabled when doing activate_mm(). According to mm-protect-activate-switch-mm.patch, actually preempt_[disable|enable]_rt() is sufficient. Inspired-by: Steven Rostedt Signed-off-by: Yong Zhang Cc: Steven Rostedt Link: http://lkml.kernel.org/r/1337061236-1766-1-git-send-email-yong.zhang0@gmail.com Signed-off-by: Thomas Gleixner --- fs/exec.c | 2 ++ mm/mmu_context.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/fs/exec.c b/fs/exec.c index 28e3b5eb2f4a..2c15772a1feb 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1028,6 +1028,7 @@ static int exec_mmap(struct mm_struct *mm) } } task_lock(tsk); + preempt_disable_rt(); local_irq_disable(); active_mm = tsk->active_mm; @@ -1047,6 +1048,7 @@ static int exec_mmap(struct mm_struct *mm) local_irq_enable(); tsk->mm->vmacache_seqnum = 0; vmacache_flush(tsk); + preempt_enable_rt(); task_unlock(tsk); if (old_mm) { up_read(&old_mm->mmap_sem); diff --git a/mm/mmu_context.c b/mm/mmu_context.c index 3e612ae748e9..d0ccc070979f 100644 --- a/mm/mmu_context.c +++ b/mm/mmu_context.c @@ -25,6 +25,7 @@ void use_mm(struct mm_struct *mm) struct task_struct *tsk = current; task_lock(tsk); + preempt_disable_rt(); active_mm = tsk->active_mm; if (active_mm != mm) { mmgrab(mm); @@ -32,6 +33,7 @@ void use_mm(struct mm_struct *mm) } tsk->mm = mm; switch_mm(active_mm, mm, tsk); + preempt_enable_rt(); task_unlock(tsk); #ifdef finish_arch_post_lock_switch finish_arch_post_lock_switch();