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On Tue, 15 Oct 2013 02:01:04 +0000
"Liu, Chuansheng" <chuansheng....@intel.com> wrote:
> We meet one issue that during trigger all CPU backtrace, but during in the
> NMI handler arch_trigger_all_cpu_backtrace_handler,
> It hit the PAGE fault, then PAGE fault is in loop, at last the thread stack
> overflow, and system panic.
>
> Anyone can give some help? Thanks.
>
>
> Panic log as below:
> ===============
> [ 15.069144] BUG: unable to handle kernel [ 15.073635] paging request at
> 1649736d
> [ 15.076379] IP: [<c200402a>] print_context_stack+0x4a/0xa0
> [ 15.082529] *pde = 00000000
> [ 15.085758] Thread overran stack, or stack corrupted
> [ 15.091303] Oops: 0000 [#1] SMP
> [ 15.094932] Modules linked in: atomisp_css2400b0_v2(+) lm3554 ov2722
> imx1x5 atmel_mxt_ts vxd392 videobuf_vmalloc videobuf_core bcm_bt_lpm bcm43241
> kct_daemon(O)
> [ 15.111093] CPU: 2 PID: 2443 Comm: Compiler Tainted: G W O 3.10.1+
> #1
I'm curious, what "Out-of-tree" module was loaded?
Read the rest from the bottom up, as that's how I wrote it :-)
> [ 15.119075] task: f213f980 ti: f0c42000 task.ti: f0c42000
> [ 15.125116] EIP: 0060:[<c200402a>] EFLAGS: 00210087 CPU: 2
> [ 15.131255] EIP is at print_context_stack+0x4a/0xa0
> [ 15.136712] EAX: 16497ffc EBX: 1649736d ECX: 986736d8 EDX: 1649736d
> [ 15.143722] ESI: 00000000 EDI: ffffe000 EBP: f0c4220c ESP: f0c421ec
> [ 15.150732] DS: 007b ES: 007b FS: 00d8 GS: 003b SS: 0068
> [ 15.156771] CR0: 80050033 CR2: 1649736d CR3: 31245000 CR4: 001007d0
> [ 15.163781] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
> [ 15.170789] DR6: ffff0ff0 DR7: 00000400
> [ 15.175076] Stack:
> [ 15.177324] 16497ffc 16496000 986736d8 ffffe000 986736d8 1649736d
> c282c148 16496000
> [ 15.186067] f0c4223c c20033b0 c282c148 c29ceecf 00000000 f0c4222c
> 986736d8 f0c4222c
> [ 15.194810] 00000000 c29ceecf 00000000 00000000 f0c42260 c20041a7
> f0c4229c c282c148
> [ 15.203549] Call Trace:
> [ 15.206295] [<c20033b0>] dump_trace+0x70/0xf0
> [ 15.211274] [<c20041a7>] show_trace_log_lvl+0x47/0x60
> [ 15.217028] [<c2003482>] show_stack_log_lvl+0x52/0xd0
> [ 15.222782] [<c2004201>] show_stack+0x21/0x50
> [ 15.227762] [<c281b38b>] dump_stack+0x16/0x18
> [ 15.232742] [<c2037cff>] warn_slowpath_common+0x5f/0x80
> [ 15.238693] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 15.244156] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 15.249621] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 15.255472] [<c2037d3d>] warn_slowpath_null+0x1d/0x20
> [ 15.261228] [<c282553a>] vmalloc_fault+0x5a/0xcf
> [ 15.266497] [<c282592f>] __do_page_fault+0x2cf/0x4a0
> [ 15.272154] [<c25e13e0>] ? logger_aio_write+0x230/0x230
> [ 15.278106] [<c2039c94>] ? console_unlock+0x314/0x440
> ... //
> [ 16.885364] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 16.891217] [<c2825b08>] do_page_fault+0x8/0x10
> [ 16.896387] [<c2823066>] error_code+0x5a/0x60
> [ 16.901367] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 16.907219] [<c208d6a0>] ? print_modules+0x20/0x90
> [ 16.912685] [<c2037cfa>] warn_slowpath_common+0x5a/0x80
> [ 16.918634] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 16.924097] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 16.929562] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 16.935415] [<c2037d3d>] warn_slowpath_null+0x1d/0x20
> [ 16.941169] [<c282553a>] vmalloc_fault+0x5a/0xcf
> [ 16.946437] [<c282592f>] __do_page_fault+0x2cf/0x4a0
> [ 16.952095] [<c25e13e0>] ? logger_aio_write+0x230/0x230
> [ 16.958046] [<c2039c94>] ? console_unlock+0x314/0x440
> [ 16.963800] [<c2003e62>] ? sys_modify_ldt+0x2/0x160
> [ 16.969362] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 16.975215] [<c2825b08>] do_page_fault+0x8/0x10
> [ 16.980386] [<c2823066>] error_code+0x5a/0x60
> [ 16.985366] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 16.991215] [<c208d6a0>] ? print_modules+0x20/0x90
> [ 16.996673] [<c2037cfa>] warn_slowpath_common+0x5a/0x80
> [ 17.002622] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 17.008086] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 17.013550] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 17.019403] [<c2037d3d>] warn_slowpath_null+0x1d/0x20
> [ 17.025159] [<c282553a>] vmalloc_fault+0x5a/0xcf
Oh look, we are constantly warning about this same fault! There's your
infinite loop.
Note the WARN_ON_ONCE() does the WARN_ON() first and then updates
__warned = true. Thus, if the WARN_ON() itself faults, then we are in
an infinite loop.
> [ 17.030428] [<c282592f>] __do_page_fault+0x2cf/0x4a0
> [ 17.036085] [<c25e13e0>] ? logger_aio_write+0x230/0x230
> [ 17.042037] [<c2039c94>] ? console_unlock+0x314/0x440
> [ 17.047790] [<c2003e62>] ? sys_modify_ldt+0x2/0x160
> [ 17.053352] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 17.059205] [<c2825b08>] do_page_fault+0x8/0x10
> [ 17.064375] [<c2823066>] error_code+0x5a/0x60
> [ 17.069354] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 17.075204] [<c208d6a0>] ? print_modules+0x20/0x90
> [ 17.080669] [<c2037cfa>] warn_slowpath_common+0x5a/0x80
> [ 17.086619] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 17.092082] [<c282553a>] ? vmalloc_fault+0x5a/0xcf
> [ 17.097546] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 17.103399] [<c2037d3d>] warn_slowpath_null+0x1d/0x20
> [ 17.109154] [<c282553a>] vmalloc_fault+0x5a/0xcf
Yep, the WARN_ON() triggered in vmalloc_fault(). We shouldn't worry
about warning in_nmi() for vmalloc faults anymore.
> [ 17.114422] [<c282592f>] __do_page_fault+0x2cf/0x4a0
> [ 17.120080] [<c206b93d>] ? update_group_power+0x1fd/0x240
> [ 17.126224] [<c227827b>] ? number.isra.2+0x32b/0x330
> [ 17.131880] [<c20679bc>] ? update_curr+0xac/0x190
> [ 17.137247] [<c227827b>] ? number.isra.2+0x32b/0x330
> [ 17.142905] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 17.148755] [<c2825b08>] do_page_fault+0x8/0x10
> [ 17.153926] [<c2823066>] error_code+0x5a/0x60
> [ 17.158905] [<c2825b00>] ? __do_page_fault+0x4a0/0x4a0
> [ 17.164760] [<c208d1a9>] ? module_address_lookup+0x29/0xb0
> [ 17.170999] [<c208dddb>] kallsyms_lookup+0x9b/0xb0
Looks like kallsyms_lookup() faulted?
> [ 17.176462] [<c208de1d>] __sprint_symbol+0x2d/0xd0
> [ 17.181926] [<c22790cc>] ? sprintf+0x1c/0x20
> [ 17.186804] [<c208def4>] sprint_symbol+0x14/0x20
> [ 17.192063] [<c208df1e>] __print_symbol+0x1e/0x40
> [ 17.197430] [<c25e00d7>] ? ashmem_shrink+0x77/0xf0
> [ 17.202895] [<c25e13e0>] ? logger_aio_write+0x230/0x230
> [ 17.208845] [<c205bdf5>] ? up+0x25/0x40
> [ 17.213242] [<c2039cb7>] ? console_unlock+0x337/0x440
> [ 17.218998] [<c2818236>] ? printk+0x38/0x3a
> [ 17.223782] [<c20006d0>] __show_regs+0x70/0x190
> [ 17.228954] [<c200353a>] show_regs+0x3a/0x1b0
> [ 17.233931] [<c2818236>] ? printk+0x38/0x3a
> [ 17.238717] [<c2824182>] arch_trigger_all_cpu_backtrace_handler+0x62/0x80
> [ 17.246413] [<c2823919>] nmi_handle.isra.0+0x39/0x60
> [ 17.252071] [<c2823a29>] do_nmi+0xe9/0x3f0
Start here and read upward.
Can you try this patch:
>From 794197cf3f563d36e5ee5b29cbf8e941163f9bc9 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org>
Date: Tue, 15 Oct 2013 12:34:56 -0400
Subject: [PATCH] x86: Remove WARN_ON(in_nmi()) from vmalloc_fault
Since the NMI iretq nesting has been fixed, there's no reason that
an NMI handler can not take a page fault for vmalloc'd code. No locks
are taken in that code path, and the software now handles nested NMIs
when the fault re-enables NMIs on iretq.
Not only that, if the vmalloc_fault() WARN_ON_ONCE() is hit, and that
warn on triggers a vmalloc fault for some reason, then we can go into
an infinite loop (the WARN_ON_ONCE() does the WARN() before updating
the variable to make it happen "once").
Reported-by: "Liu, Chuansheng" <chuansheng....@intel.com>
Signed-off-by: Steven Rostedt <rost...@goodmis.org>
---
arch/x86/mm/fault.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3aaeffc..78926c6 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -268,8 +268,6 @@ static noinline __kprobes int vmalloc_fault(unsigned long
address)
if (!(address >= VMALLOC_START && address < VMALLOC_END))
return -1;
- WARN_ON_ONCE(in_nmi());
-
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
--
1.8.1.4
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