litmus-rt.git/Documentation/kdump, branch test

kernel: add panic_on_warn

2014-12-11T01:41:10+00:00

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:
     [] dump_stack+0x46/0x58
     [] panic+0xd0/0x204
     [] ? init_dummy+0x1f/0x30 [dummy_module]
     [] warn_slowpath_common+0xd0/0xd0
     [] ? dummy_greetings+0x40/0x40 [dummy_module]
     [] warn_slowpath_null+0x1a/0x20
     [] init_dummy+0x1f/0x30 [dummy_module]
     [] do_one_initcall+0xd4/0x210
     [] ? __vunmap+0xc2/0x110
     [] load_module+0x16a9/0x1b30
     [] ? store_uevent+0x70/0x70
     [] ? copy_module_from_fd.isra.44+0x129/0x180
     [] SyS_finit_module+0xa6/0xd0
     [] 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 
Cc: Jonathan Corbet 
Cc: Rusty Russell 
Cc: "H. Peter Anvin" 
Cc: Andi Kleen 
Cc: Masami Hiramatsu 
Acked-by: Yasuaki Ishimatsu 
Cc: Fabian Frederick 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/kdump/kdump.txt: add ARM description

2014-08-29T23:28:17+00:00

Add arm specific parts to kdump kernel documentation.

Signed-off-by: Hu Keping 
Acked-by: Vivek Goyal 
Cc: Haren Myneni 
Cc: Rob Landley 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2013-07-04T18:40:58+00:00

Pull trivial tree updates from Jiri Kosina:
 "The usual stuff from trivial tree"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits)
  treewide: relase -> release
  Documentation/cgroups/memory.txt: fix stat file documentation
  sysctl/net.txt: delete reference to obsolete 2.4.x kernel
  spinlock_api_smp.h: fix preprocessor comments
  treewide: Fix typo in printk
  doc: device tree: clarify stuff in usage-model.txt.
  open firmware: "/aliasas" -> "/aliases"
  md: bcache: Fixed a typo with the word 'arithmetic'
  irq/generic-chip: fix a few kernel-doc entries
  frv: Convert use of typedef ctl_table to struct ctl_table
  sgi: xpc: Convert use of typedef ctl_table to struct ctl_table
  doc: clk: Fix incorrect wording
  Documentation/arm/IXP4xx fix a typo
  Documentation/networking/ieee802154 fix a typo
  Documentation/DocBook/media/v4l fix a typo
  Documentation/video4linux/si476x.txt fix a typo
  Documentation/virtual/kvm/api.txt fix a typo
  Documentation/early-userspace/README fix a typo
  Documentation/video4linux/soc-camera.txt fix a typo
  lguest: fix CONFIG_PAE -> CONFIG_x86_PAE in comment
  ...

Documentation/kdump/kdump.txt: remove /dev/oldmem description

2013-07-03T23:08:03+00:00

Signed-off-by: Zhang Yanfei 
Cc: Vivek Goyal 
Cc: "Eric W. Biederman" 
Cc: "H. Peter Anvin" 
Cc: Benjamin Herrenschmidt 
Cc: Dave Hansen 
Cc: Fenghua Yu 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: Matt Fleming 
Cc: Michael Holzheu 
Cc: Paul Mackerras 
Cc: Ralf Baechle 
Cc: Tony Luck 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/kdump: Remove TODO in this document

2013-05-28T10:02:13+00:00

We have already had the relocatable kernel, so just remove
the TODO in the kdump document.

Signed-off-by: Zhang Yanfei 
Acked-by: Rob Landley 
Acked-by: Vivek Goyal 
Signed-off-by: Jiri Kosina

Add size restriction to the kdump documentation

2013-04-02T16:40:03+00:00

In efi_init() memory aligns in IA64_GRANULE_SIZE(16M). If set "crashkernel=1024M-:600M"
and use sparse memory model, when crash kernel booting it changes [128M-728M] to [128M-720M].

But initrd memory is in [709M-727M], and virt_addr_valid() *can not* check the invalid pages
when freeing initrd memory, because there are some pages missed at the end of the section,
and this causes error.

...
Unpacking initramfs...
Freeing initrd memory: 19648kB freed
BUG: Bad page state in process swapper  pfn:02d00
page:e0000000102dd800 flags:(null) count:0 mapcount:1 mapping:(null) index:0

Call Trace:
 [] show_stack+0x80/0xa0
                                sp=e000000021e8fbd0 bsp=e000000021e81360
 [] dump_stack+0x30/0x50
                                sp=e000000021e8fda0 bsp=e000000021e81348
 [] bad_page+0x280/0x380
                                sp=e000000021e8fda0 bsp=e000000021e81308
 [] free_hot_cold_page+0x3a0/0x5c0
                                sp=e000000021e8fda0 bsp=e000000021e812a0
 [] free_hot_page+0x30/0x60
                                sp=e000000021e8fda0 bsp=e000000021e81280
 [] __free_pages+0xb0/0xe0
                                sp=e000000021e8fda0 bsp=e000000021e81258
 [] free_pages+0xa0/0xc0
                                sp=e000000021e8fda0 bsp=e000000021e81230
 [] free_initrd_mem+0x230/0x290
                                sp=e000000021e8fda0 bsp=e000000021e811d8
 [] populate_rootfs+0x1c0/0x280
                                sp=e000000021e8fdb0 bsp=e000000021e811a0
 [] do_one_initcall+0x3b0/0x3e0
                                sp=e000000021e8fdb0 bsp=e000000021e81158
 [] kernel_init+0x3f0/0x4b0
                                sp=e000000021e8fdb0 bsp=e000000021e81108
 [] kernel_thread_helper+0xd0/0x100
                                sp=e000000021e8fe30 bsp=e000000021e810e0
 [] start_kernel_thread+0x20/0x40
                                sp=e000000021e8fe30 bsp=e000000021e810e0
...

In "http://marc.info/?l=linux-arch&m=136147092429314&w=2" Tony said:
"Perhaps in Documentation/kdump/kdump.txt (which the crashkernel entry
in kernel-parameters.txt points at).  The ia64 section of kdump.txt
notes that the start address will be rounded up to a GRANULE boundary,
but doesn't talk about restrictions on the size."

This patch add size restriction to the documentation of kdump.

Signed-off-by: Xishi Qiu 
Signed-off-by: Tony Luck

kexec: update URL of kexec homepage

2012-07-19T01:35:57+00:00

The referenced html file does not exist anymore. Replace the URL with
the current project homepage.

Signed-off-by: Olaf Hering 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[S390] Add s390x description to Documentation/kdump/kdump.txt

2011-12-27T10:27:13+00:00

Add s390x specific parts to kdump kernel documentation.

Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

kdump: update kexec-tools URL and Vivek's email

2010-11-25T13:36:38+00:00

Signed-off-by: Simon Horman 
Signed-off-by: Jiri Kosina

trivial: Miscellaneous documentation typo fixes

2009-06-12T16:01:47+00:00

Fix various typos in documentation txts.

Signed-off-by: Matt LaPlante 
Signed-off-by: Jiri Kosina