unimore/kernel-hacking-2024-linux-steffo
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Linux kernel modifications for the Kernel Hacking exam
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Johannes Weiner e27be240df mm: memcg: make sure memory.events is uptodate when waking pollers 
Commit a983b5ebee ("mm: memcontrol: fix excessive complexity in
memory.stat reporting") added per-cpu drift to all memory cgroup stats
and events shown in memory.stat and memory.events.

For memory.stat this is acceptable.  But memory.events issues file
notifications, and somebody polling the file for changes will be
confused when the counters in it are unchanged after a wakeup.

Luckily, the events in memory.events - MEMCG_LOW, MEMCG_HIGH, MEMCG_MAX,
MEMCG_OOM - are sufficiently rare and high-level that we don't need
per-cpu buffering for them: MEMCG_HIGH and MEMCG_MAX would be the most
frequent, but they're counting invocations of reclaim, which is a
complex operation that touches many shared cachelines.

This splits memory.events from the generic VM events and tracks them in
their own, unbuffered atomic counters.  That's also cleaner, as it
eliminates the ugly enum nesting of VM and cgroup events.

[hannes@cmpxchg.org: "array subscript is above array bounds"]
  Link: http://lkml.kernel.org/r/20180406155441.GA20806@cmpxchg.org
Link: http://lkml.kernel.org/r/20180405175507.GA24817@cmpxchg.org
Fixes: a983b5ebee ("mm: memcontrol: fix excessive complexity in memory.stat reporting")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:31 -07:00
arch c6x changes 4.17 2018-04-10 11:50:14 -07:00
block for-4.17/block-20180402 2018-04-05 14:27:02 -07:00
certs
crypto MIPS changes for 4.17 2018-04-10 11:39:22 -07:00
Documentation Documentation/vm/hmm.txt: typos and syntaxes fixes 2018-04-11 10:28:31 -07:00
drivers mm: check __highest_present_section_nr directly in memory_dev_init() 2018-04-11 10:28:31 -07:00
firmware
fs dcache: account external names as indirectly reclaimable memory 2018-04-11 10:28:29 -07:00
include mm: memcg: make sure memory.events is uptodate when waking pollers 2018-04-11 10:28:31 -07:00
init New features: 2018-04-10 11:27:30 -07:00
ipc Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-04-03 19:15:32 -07:00
kernel New features: 2018-04-10 11:27:30 -07:00
lib New features: 2018-04-10 11:27:30 -07:00
LICENSES
mm mm: memcg: make sure memory.events is uptodate when waking pollers 2018-04-11 10:28:31 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-09 17:04:10 -07:00
samples VFIO updates for v4.17-rc1 2018-04-06 19:44:27 -07:00
scripts Leaking-addresses patches for 4.17-rc1 2018-04-07 11:56:33 -07:00
security New features: 2018-04-10 11:27:30 -07:00
sound sound fixes for 4.17-rc1 2018-04-10 10:16:04 -07:00
tools New features: 2018-04-10 11:27:30 -07:00
usr
virt
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap Merge candidates for 4.17 merge window 2018-04-06 17:35:43 -07:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS mm/hmm: documentation editorial update to HMM documentation 2018-04-11 10:28:30 -07:00
Makefile Kconfig updates for v4.17 2018-04-03 16:28:01 -07:00
README

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.