linux.git/Documentation/kdump, branch v4.8

kdump: fix dmesg gdbmacro to work with record based printk

2016-06-03T22:06:22+00:00

Commit 7ff9554bb578 ("printk: convert byte-buffer to variable-length
record buffer") introduced a record based printk buffer.  Modify
gdbmacros.txt to parse this new structure so dmesg will work properly.

Link: http://lkml.kernel.org/r/1463515794-1599-1-git-send-email-minyard@acm.org
Signed-off-by: Corey Minyard 
Cc: Dave Young 
Cc: Baoquan He 
Cc: Vivek Goyal 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kdump: fix gdb macros work work with newer and 64-bit kernels

2016-05-24T00:04:14+00:00

Lots of little changes needed to be made to clean these up, remove the
four byte pointer assumption and traverse the pid queue properly.  Also
consolidate the traceback code into a single function instead of having
three copies of it.

Link: http://lkml.kernel.org/r/1462926655-9390-1-git-send-email-minyard@acm.org
Signed-off-by: Corey Minyard 
Acked-by: Baoquan He 
Cc: Vivek Goyal 
Cc: Haren Myneni 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ARM: kexec: fix crashkernel= handling

2016-05-03T10:13:45+00:00

When the kernel crashkernel parameter is specified with just a size, we
are supposed to allocate a region from RAM to store the crashkernel.
However, ARM merely reserves physical address zero with no checking that
there is even RAM there.

Fix this by lifting similar code from x86, importing it to ARM with the
ARM specific parameters added.  In the absence of any platform specific
information, we allocate the crashkernel region from the first 512MB of
physical memory.

Update the kdump documentation to reflect this change.

Signed-off-by: Russell King 
Reviewed-by: Pratyush Anand

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