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9e3961a097
There have been several times where I have had to rebuild a kernel to
cause a panic when hitting a WARN() in the code in order to get a crash
dump from a system. Sometimes this is easy to do, other times (such as
in the case of a remote admin) it is not trivial to send new images to
the user.
A much easier method would be a switch to change the WARN() over to a
panic. This makes debugging easier in that I can now test the actual
image the WARN() was seen on and I do not have to engage in remote
debugging.
This patch adds a panic_on_warn kernel parameter and
/proc/sys/kernel/panic_on_warn calls panic() in the
warn_slowpath_common() path. The function will still print out the
location of the warning.
An example of the panic_on_warn output:
The first line below is from the WARN_ON() to output the WARN_ON()'s
location. After that the panic() output is displayed.
WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]()
Kernel panic - not syncing: panic_on_warn set ...
CPU: 30 PID: 11698 Comm: insmod Tainted: G W OE 3.17.0+ #57
Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013
0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190
0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec
ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df
Call Trace:
[<ffffffff81665190>] dump_stack+0x46/0x58
[<ffffffff8165e2ec>] panic+0xd0/0x204
[<ffffffffa038e05f>] ? init_dummy+0x1f/0x30 [dummy_module]
[<ffffffff81076b90>] warn_slowpath_common+0xd0/0xd0
[<ffffffffa038e040>] ? dummy_greetings+0x40/0x40 [dummy_module]
[<ffffffff81076c8a>] warn_slowpath_null+0x1a/0x20
[<ffffffffa038e05f>] init_dummy+0x1f/0x30 [dummy_module]
[<ffffffff81002144>] do_one_initcall+0xd4/0x210
[<ffffffff811b52c2>] ? __vunmap+0xc2/0x110
[<ffffffff810f8889>] load_module+0x16a9/0x1b30
[<ffffffff810f3d30>] ? store_uevent+0x70/0x70
[<ffffffff810f49b9>] ? copy_module_from_fd.isra.44+0x129/0x180
[<ffffffff810f8ec6>] SyS_finit_module+0xa6/0xd0
[<ffffffff8166cf29>] system_call_fastpath+0x12/0x17
Successfully tested by me.
hpa said: There is another very valid use for this: many operators would
rather a machine shuts down than being potentially compromised either
functionally or security-wise.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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|---|---|---|
| .. | ||
| ABI | ||
| accounting | ||
| acpi | ||
| aoe | ||
| arm | ||
| arm64 | ||
| auxdisplay | ||
| backlight | ||
| blackfin | ||
| block | ||
| blockdev | ||
| bus-devices | ||
| cdrom | ||
| cgroups | ||
| connector | ||
| console | ||
| cpu-freq | ||
| cpuidle | ||
| cris | ||
| crypto | ||
| development-process | ||
| device-mapper | ||
| devicetree | ||
| DocBook | ||
| driver-model | ||
| dvb | ||
| early-userspace | ||
| EDID | ||
| extcon | ||
| fault-injection | ||
| fb | ||
| filesystems | ||
| firmware_class | ||
| fmc | ||
| frv | ||
| gpio | ||
| hid | ||
| hwmon | ||
| i2c | ||
| i2o | ||
| ia64 | ||
| ide | ||
| infiniband | ||
| input | ||
| ioctl | ||
| isdn | ||
| ja_JP | ||
| kbuild | ||
| kdump | ||
| ko_KR | ||
| laptops | ||
| leds | ||
| locking | ||
| m68k | ||
| memory-devices | ||
| metag | ||
| mic | ||
| mips | ||
| misc-devices | ||
| mmc | ||
| mn10300 | ||
| mtd | ||
| namespaces | ||
| netlabel | ||
| networking | ||
| nfc | ||
| nios2 | ||
| parisc | ||
| PCI | ||
| pcmcia | ||
| phy | ||
| platform | ||
| power | ||
| powerpc | ||
| pps | ||
| prctl | ||
| pti | ||
| ptp | ||
| rapidio | ||
| RCU | ||
| s390 | ||
| scheduler | ||
| scsi | ||
| security | ||
| serial | ||
| sh | ||
| sound | ||
| spi | ||
| sysctl | ||
| target | ||
| thermal | ||
| timers | ||
| tpm | ||
| trace | ||
| usb | ||
| vDSO | ||
| video4linux | ||
| virtual | ||
| vm | ||
| w1 | ||
| watchdog | ||
| wimax | ||
| x86 | ||
| xtensa | ||
| zh_CN | ||
| 00-INDEX | ||
| applying-patches.txt | ||
| assoc_array.txt | ||
| atomic_ops.txt | ||
| bad_memory.txt | ||
| basic_profiling.txt | ||
| bcache.txt | ||
| binfmt_misc.txt | ||
| braille-console.txt | ||
| bt8xxgpio.txt | ||
| btmrvl.txt | ||
| BUG-HUNTING | ||
| bus-virt-phys-mapping.txt | ||
| cachetlb.txt | ||
| Changes | ||
| circular-buffers.txt | ||
| clk.txt | ||
| coccinelle.txt | ||
| CodingStyle | ||
| cpu-hotplug.txt | ||
| cpu-load.txt | ||
| cputopology.txt | ||
| crc32.txt | ||
| dcdbas.txt | ||
| debugging-modules.txt | ||
| debugging-via-ohci1394.txt | ||
| dell_rbu.txt | ||
| devices.txt | ||
| digsig.txt | ||
| DMA-API-HOWTO.txt | ||
| DMA-API.txt | ||
| DMA-attributes.txt | ||
| dma-buf-sharing.txt | ||
| DMA-ISA-LPC.txt | ||
| dmaengine.txt | ||
| dmatest.txt | ||
| dontdiff | ||
| dynamic-debug-howto.txt | ||
| edac.txt | ||
| efi-stub.txt | ||
| eisa.txt | ||
| email-clients.txt | ||
| flexible-arrays.txt | ||
| futex-requeue-pi.txt | ||
| gcov.txt | ||
| highuid.txt | ||
| HOWTO | ||
| hsi.txt | ||
| hw_random.txt | ||
| hwspinlock.txt | ||
| init.txt | ||
| initrd.txt | ||
| intel_txt.txt | ||
| Intel-IOMMU.txt | ||
| io_ordering.txt | ||
| io-mapping.txt | ||
| iostats.txt | ||
| IPMI.txt | ||
| IRQ-affinity.txt | ||
| IRQ-domain.txt | ||
| IRQ.txt | ||
| irqflags-tracing.txt | ||
| isapnp.txt | ||
| java.txt | ||
| kernel-doc-nano-HOWTO.txt | ||
| kernel-docs.txt | ||
| kernel-parameters.txt | ||
| kernel-per-CPU-kthreads.txt | ||
| kmemcheck.txt | ||
| kmemleak.txt | ||
| kobject.txt | ||
| kprobes.txt | ||
| kref.txt | ||
| ldm.txt | ||
| local_ops.txt | ||
| lockup-watchdogs.txt | ||
| logo.gif | ||
| logo.txt | ||
| lzo.txt | ||
| magic-number.txt | ||
| mailbox.txt | ||
| Makefile | ||
| ManagementStyle | ||
| md.txt | ||
| media-framework.txt | ||
| memory-barriers.txt | ||
| memory-hotplug.txt | ||
| module-signing.txt | ||
| mono.txt | ||
| nommu-mmap.txt | ||
| numastat.txt | ||
| oops-tracing.txt | ||
| padata.txt | ||
| parport-lowlevel.txt | ||
| parport.txt | ||
| percpu-rw-semaphore.txt | ||
| phy.txt | ||
| pi-futex.txt | ||
| pinctrl.txt | ||
| pnp.txt | ||
| preempt-locking.txt | ||
| printk-formats.txt | ||
| pwm.txt | ||
| ramoops.txt | ||
| rbtree.txt | ||
| remoteproc.txt | ||
| rfkill.txt | ||
| robust-futex-ABI.txt | ||
| robust-futexes.txt | ||
| rpmsg.txt | ||
| rtc.txt | ||
| SAK.txt | ||
| SecurityBugs | ||
| serial-console.txt | ||
| sgi-ioc4.txt | ||
| SM501.txt | ||
| smsc_ece1099.txt | ||
| sparse.txt | ||
| stable_api_nonsense.txt | ||
| stable_kernel_rules.txt | ||
| static-keys.txt | ||
| SubmitChecklist | ||
| SubmittingDrivers | ||
| SubmittingPatches | ||
| svga.txt | ||
| sysfs-rules.txt | ||
| sysrq.txt | ||
| this_cpu_ops.txt | ||
| unaligned-memory-access.txt | ||
| unicode.txt | ||
| unshare.txt | ||
| vfio.txt | ||
| VGA-softcursor.txt | ||
| vgaarbiter.txt | ||
| video-output.txt | ||
| vme_api.txt | ||
| volatile-considered-harmful.txt | ||
| workqueue.txt | ||
| xillybus.txt | ||
| xz.txt | ||
| zorro.txt | ||
