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Thomas Gleixner a0c9259dc4 irq/matrix: Spread interrupts on allocation
Keith reported an issue with vector space exhaustion on a server machine
which is caused by the i40e driver allocating 168 MSI interrupts when the
driver is initialized, even when most of these interrupts are not used at
all.

The x86 vector allocation code tries to avoid the immediate allocation with
the reservation mode, but the card uses MSI and does not support MSI entry
masking, which prevents reservation mode and requires immediate vector
allocation.

The matrix allocator is a bit naive and prefers the first CPU in the
cpumask which describes the possible target CPUs for an allocation. That
results in allocating all 168 vectors on CPU0 which later causes vector
space exhaustion when the NVMe driver tries to allocate managed interrupts
on each CPU for the per CPU queues.

Avoid this by finding the CPU which has the lowest vector allocation count
to spread out the non managed interrupt accross the possible target CPUs.

Fixes: 2f75d9e1c9 ("genirq: Implement bitmap matrix allocator")
Reported-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Keith Busch <keith.busch@intel.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801171557330.1777@nanos
2018-01-18 11:38:41 +01:00
Documentation Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-14 09:51:25 -08:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-17 12:30:06 -08:00
block block: drain queue before waiting for q_usage_counter becoming zero 2018-01-05 09:09:48 -07:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-12 09:47:58 -08:00
drivers Fifth pull request for 4.15-rc 2018-01-16 16:47:40 -08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-06 17:13:21 -08:00
include Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-17 12:28:22 -08:00
init Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-12 10:23:59 -08:00
ipc Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
kernel irq/matrix: Spread interrupts on allocation 2018-01-18 11:38:41 +01:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2018-01-10 11:17:21 -05:00
mm kmemleak: allow to coexist with fault injection 2018-01-13 10:42:48 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-16 12:45:30 -08:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2017-12-03 13:08:30 -05:00
scripts Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-17 11:54:56 -08:00
security Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-14 09:51:25 -08:00
sound ALSA: seq: Make ioctls race-free 2018-01-11 14:37:51 +01:00
tools Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-17 11:54:56 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM/ARM Fixes for v4.15, Round 2 2017-12-18 12:57:43 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS, nilfs2: change project home URLs 2018-01-13 10:42:48 -08:00
Makefile Linux 4.15-rc8 2018-01-14 15:32:30 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README

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.