Go to file
David Rientjes c257a340ed fs, epoll: short circuit fetching events if thread has been killed
We've encountered zombies that are waiting for a thread to exit that are
looping in ep_poll() almost endlessly although there is a pending
SIGKILL as a result of a group exit.

This happens because we always find ep_events_available() and fetch more
events and never are able to check for signal_pending() that would break
from the loop and return -EINTR.

Special case fatal signals and break immediately to guarantee that we
loop to fetch more events and delay making a timely exit.

It would also be possible to simply move the check for signal_pending()
higher than checking for ep_events_available(), but there have been no
reports of delayed signal handling other than SIGKILL preventing zombies
from exiting that would be fixed by this.

It fixes an issue for us where we have witnessed zombies sticking around
for at least O(minutes), but considering the code has been like this
forever and nobody else has complained that I have found, I would simply
queue it up for 4.12.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1705031722350.76784@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jan Kara <jack@suse.cz>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-10 16:32:36 -07:00
arch lib/extable.c: use bsearch() library function in search_extable() 2017-07-10 16:32:35 -07:00
block Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-06 20:57:13 -07:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
Documentation mm: document highmem_is_dirtyable sysctl 2017-07-10 16:32:32 -07:00
drivers ARM: fix rd_size declaration 2017-07-10 16:32:34 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs fs, epoll: short circuit fetching events if thread has been killed 2017-07-10 16:32:36 -07:00
include lib/extable.c: use bsearch() library function in search_extable() 2017-07-10 16:32:35 -07:00
init mm: allow slab_nomerge to be set at build time 2017-07-06 16:24:31 -07:00
ipc mqueue: fix a use-after-free in sys_mq_notify() 2017-07-09 14:37:19 -07:00
kernel lib/extable.c: use bsearch() library function in search_extable() 2017-07-10 16:32:35 -07:00
lib lib/bsearch.c: micro-optimize pivot position calculation 2017-07-10 16:32:35 -07:00
mm kasan: make get_wild_bug_type() static 2017-07-10 16:32:33 -07:00
net mpls: fix uninitialized in_label var warning in mpls_getroute 2017-07-08 11:26:41 +01:00
samples bpf: fix return in load_bpf_file 2017-07-05 09:05:28 +01:00
scripts checkpatch: improve multi-line alignment test 2017-07-10 16:32:35 -07:00
security Merge branch 'work.memdup_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-05 16:05:24 -07:00
sound main drm pull for v4.13 2017-07-09 18:48:37 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-09 10:49:47 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt PPC: 2017-07-06 18:38:31 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS MAINTAINERS: give proc sysctl some maintainer love 2017-07-10 16:32:34 -07:00
Makefile Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.