do_signal() does __put_user() which can fault, resulting in a might_sleep() warning in down_read(&mm->mmap_sem) and a "scheduling while atomic" warning when mmap_sem is contented. On swarm this also results in: WARNING: at kernel/smp.c:459 smp_call_function_many+0x148/0x398() Modules linked in: Call Trace: [<ffffffff804b48a4>] dump_stack+0x1c/0x50 [<ffffffff8013dc94>] warn_slowpath_common+0x8c/0xc8 [<ffffffff8013dcfc>] warn_slowpath_null+0x2c/0x40 [<ffffffff801864a0>] smp_call_function_many+0x148/0x398 [<ffffffff80186748>] smp_call_function+0x58/0xa8 [<ffffffff80119b5c>] r4k_flush_data_cache_page+0x54/0xd8 [<ffffffff801f39bc>] handle_pte_fault+0xa9c/0xad0 [<ffffffff801f40d0>] handle_mm_fault+0x158/0x200 [<ffffffff80115548>] do_page_fault+0x218/0x3b0 [<ffffffff80102744>] ret_from_exception+0x0/0x10 [<ffffffff8010eb18>] copy_siginfo_to_user32+0x50/0x298 [<ffffffff8010edf0>] setup_rt_frame_32+0x90/0x250 [<ffffffff80106414>] do_notify_resume+0x154/0x358 [<ffffffff80102930>] work_notifysig+0xc/0x14 Enable interrupts in do_signal() before delivering signals. Might be done in the entry code before calling do_notify_resume(), but I leave that for the MIPS ASM wizards. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- arch/mips/kernel/signal.c | 2 ++ 1 file changed, 2 insertions(+) Index: linux-2.6/arch/mips/kernel/signal.c =================================================================== --- linux-2.6.orig/arch/mips/kernel/signal.c +++ linux-2.6/arch/mips/kernel/signal.c @@ -603,6 +603,8 @@ static void do_signal(struct pt_regs *re if (!user_mode(regs)) return; + local_irq_enable(); + if (test_thread_flag(TIF_RESTORE_SIGMASK)) oldset = ¤t->saved_sigmask; else
