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Michal Hocko 1c6fb1d89e mm: print more information about mapping in __dump_page
I have been promissing to improve memory offlining failures debugging for
quite some time.  As things stand now we get only very limited information
in the kernel log when the offlining fails.  It is usually only

[ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed

with no further details.  We do not know what exactly fails and for what
reason.  Whenever I was forced to debug such a failure I've always had to
do a debugging patch to tell me more.  We can enable some tracepoints but
it would be much better to get a better picture without using them.

This patch series does 2 things.  The first one is to make dump_page more
usable by printing more information about the mapping patch 1.  Then it
reduces the log level from emerg to warning so that this function is
usable from less critical context patch 2.  Then I have added more
detailed information about the offlining failure patch 4 and finally add
dump_page to isolation and offlining migration paths.  Patch 3 is a
trivial cleanup.

This patch (of 6):

__dump_page prints the mapping pointer but that is quite unhelpful for
many reports because the pointer itself only helps to distinguish anon/ksm
mappings from other ones (because of lowest bits set).  Sometimes it would
be much more helpful to know what kind of mapping that is actually and if
we know this is a file mapping then also try to resolve the dentry name.

[dan.carpenter@oracle.com: fix a width vs precision bug in printk]
  Link: http://lkml.kernel.org/r/20181123072135.gqvblm2vdujbvfjs@kili.mountain
[mhocko@kernel.org: use %dp to print dentry]
  Link: http://lkml.kernel.org/r/20181125080834.GB12455@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20181107101830.17405-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:46 -08:00
Documentation kasan: update documentation 2018-12-28 12:11:44 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch sh: lib: convert to SPDX identifiers 2018-12-28 12:11:45 -08:00
block block: Fix null_blk_zoned creation failure with small number of zones 2018-12-11 16:19:38 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
drivers Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs ocfs2: don't clear bh uptodate for block read 2018-12-28 12:11:46 -08:00
include writeback: don't decrement wb->refcnt if !wb->bdi 2018-12-28 12:11:46 -08:00
init debugobjects: call debug_objects_mem_init eariler 2018-12-28 12:11:45 -08:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
lib debugobjects: call debug_objects_mem_init eariler 2018-12-28 12:11:45 -08:00
mm mm: print more information about mapping in __dump_page 2018-12-28 12:11:46 -08:00
net Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-12-27 13:04:52 -08:00
scripts scripts/tags.sh: add more declarations 2018-12-28 12:11:44 -08:00
security Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
sound xen: features and fixes for 4.21 2018-12-26 11:35:07 -08:00
tools Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-12-26 13:07:19 -08:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge tag 'nand/for-4.21' of git://git.infradead.org/linux-mtd into mtd/next 2018-12-18 19:59:16 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: update entry for MMP platform 2018-12-03 12:39:57 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
Makefile Linux 4.20 2018-12-23 15:55:59 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.