From 1f717929e987fc55bb6be02df994945f8edbd46c Mon Sep 17 00:00:00 2001 From: Ralf Baechle Date: Wed, 27 Jul 2011 11:44:47 +0100 Subject: [PATCH] MIPS: Handle __put_user() sleeping. 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: [] dump_stack+0x1c/0x50 [] warn_slowpath_common+0x8c/0xc8 [] warn_slowpath_null+0x2c/0x40 [] smp_call_function_many+0x148/0x398 [] smp_call_function+0x58/0xa8 [] r4k_flush_data_cache_page+0x54/0xd8 [] handle_pte_fault+0xa9c/0xad0 [] handle_mm_fault+0x158/0x200 [] do_page_fault+0x218/0x3b0 [] ret_from_exception+0x0/0x10 [] copy_siginfo_to_user32+0x50/0x298 [] setup_rt_frame_32+0x90/0x250 [] do_notify_resume+0x154/0x358 [] work_notifysig+0xc/0x14 Fixed by enabling interrupts in do_notify_resume before delivering signals. [ralf@linux-mips.org: Reported and original fix by tglx but I wanted to minimize the amount of code being run with interrupts disabled so I moved the local_irq_disable() call right into do_notify_resume. Which is saner than doing it in entry.S.] Reported-by: Thomas Gleixner Signed-off-by: Ralf Baechle --- arch/mips/kernel/signal.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c index dbbe0ce48d89..f8524003676a 100644 --- a/arch/mips/kernel/signal.c +++ b/arch/mips/kernel/signal.c @@ -8,6 +8,7 @@ * Copyright (C) 1999, 2000 Silicon Graphics, Inc. */ #include +#include #include #include #include @@ -658,6 +659,8 @@ static void do_signal(struct pt_regs *regs) asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) { + local_irq_enable(); + /* deal with pending signal delivery */ if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK)) do_signal(regs); -- 2.34.1