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Date: Tue, 15 Oct 2013 12:40:28 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: "Liu, Chuansheng" <chuansheng.liu@...el.com> Cc: "Ingo Molnar (mingo@...nel.org)" <mingo@...nel.org>, "hpa@...or.com" <hpa@...or.com>, "fweisbec@...il.com" <fweisbec@...il.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>, "Peter Zijlstra (peterz@...radead.org)" <peterz@...radead.org>, "x86@...nel.org" <x86@...nel.org>, "'linux-kernel@...r.kernel.org' (linux-kernel@...r.kernel.org)" <linux-kernel@...r.kernel.org>, "Wang, Xiaoming" <xiaoming.wang@...el.com>, "Li, Zhuangzhi" <zhuangzhi.li@...el.com> Subject: Re: Panic and page fault in loop during handling NMI backtrace handler BTW, please do not send out HTML email, as that gets blocked from going to LKML. On Tue, 15 Oct 2013 02:01:04 +0000 "Liu, Chuansheng" <chuansheng.liu@...el.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)" <rostedt@...dmis.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.liu@...el.com> Signed-off-by: Steven Rostedt <rostedt@...dmis.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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