From e8bff74afbdb4ad72bf6135c84289c47cf557892 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 13 Feb 2008 20:21:06 +0100 Subject: [PATCH] x86: fix "BUG: sleeping function called from invalid context" in print_vma_addr() Jiri Kosina reported the following deadlock scenario with show_unhandled_signals enabled: [ 68.379022] gnome-settings-[2941] trap int3 ip:3d2c840f34 sp:7fff36f5d100 error:0<3>BUG: sleeping function called from invalid context at kernel/rwsem.c:21 [ 68.379039] in_atomic():1, irqs_disabled():0 [ 68.379044] no locks held by gnome-settings-/2941. [ 68.379050] Pid: 2941, comm: gnome-settings- Not tainted 2.6.25-rc1 #30 [ 68.379054] [ 68.379056] Call Trace: [ 68.379061] <#DB> [] ? __debug_show_held_locks+0x13/0x30 [ 68.379109] [] __might_sleep+0xe5/0x110 [ 68.379123] [] down_read+0x20/0x70 [ 68.379137] [] print_vma_addr+0x3a/0x110 [ 68.379152] [] do_trap+0xf5/0x170 [ 68.379168] [] do_int3+0x7b/0xe0 [ 68.379180] [] int3+0x9f/0xd0 [ 68.379203] <> [ 68.379229] in libglib-2.0.so.0.1505.0[3d2c800000+dc000] and tracked it down to: commit 03252919b79891063cf99145612360efbdf9500b Author: Andi Kleen Date: Wed Jan 30 13:33:18 2008 +0100 x86: print which shared library/executable faulted in segfault etc. messages the problem is that we call down_read() from an atomic context. Solve this by returning from print_vma_addr() if the preempt count is elevated. Update preempt_conditional_sti / preempt_conditional_cli to unconditionally lift the preempt count even on !CONFIG_PREEMPT. Reported-by: Jiri Kosina Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps_64.c | 4 ++-- mm/memory.c | 7 +++++++ 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c index efc66df728b6..045466681911 100644 --- a/arch/x86/kernel/traps_64.c +++ b/arch/x86/kernel/traps_64.c @@ -84,7 +84,7 @@ static inline void conditional_sti(struct pt_regs *regs) static inline void preempt_conditional_sti(struct pt_regs *regs) { - preempt_disable(); + inc_preempt_count(); if (regs->flags & X86_EFLAGS_IF) local_irq_enable(); } @@ -95,7 +95,7 @@ static inline void preempt_conditional_cli(struct pt_regs *regs) local_irq_disable(); /* Make sure to not schedule here because we could be running on an exception stack. */ - preempt_enable_no_resched(); + dec_preempt_count(); } int kstack_depth_to_print = 12; diff --git a/mm/memory.c b/mm/memory.c index 717aa0e3be2d..55b97ef6de11 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2711,6 +2711,13 @@ void print_vma_addr(char *prefix, unsigned long ip) struct mm_struct *mm = current->mm; struct vm_area_struct *vma; + /* + * Do not print if we are in atomic + * contexts (in exception stacks, etc.): + */ + if (preempt_count()) + return; + down_read(&mm->mmap_sem); vma = find_vma(mm, ip); if (vma && vma->vm_file) {