From mboxrd@z Thu Jan  1 00:00:00 1970
From: vineet.gupta1@synopsys.com (Vineet Gupta)
Date: Wed, 19 Dec 2018 17:16:39 -0800
Subject: [PATCH 1/2] ARC: show_regs: avoid page allocator
In-Reply-To: <1545239047.14089.13.camel@synopsys.com>
References: <1545159239-30628-1-git-send-email-vgupta@synopsys.com>
 <1545159239-30628-2-git-send-email-vgupta@synopsys.com>
 <1545239047.14089.13.camel@synopsys.com>
List-ID: <linux-snps-arc@lists.infradead.org>
Message-ID: <49f9edc9-87ee-1efc-58f8-b0d9a52c8a49@synopsys.com>
To: linux-snps-arc@lists.infradead.org

On 12/19/18 9:04 AM, Eugeniy Paltsev wrote:
> As I can see x86 use print_vma_addr() in their show_signal_msg()
> function which allocate page with __get_free_page(GFP_NOWAIT);

Indeed with that the __get_free_page() lockdep splat is gone.

There's a different one now hence my other patch.

| [ARCLinux]# ./segv-null-ptr
| potentially unexpected fatal signal 11.
| BUG: sleeping function called from invalid context at kernel/fork.c:1011
| in_atomic(): 1, irqs_disabled(): 0, pid: 70, name: segv-null-ptr
| no locks held by segv-null-ptr/70.
| CPU: 0 PID: 70 Comm: segv-null-ptr Not tainted 4.18.0+ #69
|
| Stack Trace:
|  arc_unwind_core+0xcc/0x100
|  ___might_sleep+0x17a/0x190
|  mmput+0x16/0xb8
|  show_regs+0x52/0x310
|  get_signal+0x5ee/0x610
|  do_signal+0x2c/0x218
|  resume_user_mode_begin+0x90/0xd8