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Dennis Zhou 72682b162d percpu: add __GFP_NORETRY semantics to the percpu balancing path
commit 47504ee04b upstream.

Percpu memory using the vmalloc area based chunk allocator lazily
populates chunks by first requesting the full virtual address space
required for the chunk and subsequently adding pages as allocations come
through. To ensure atomic allocations can succeed, a workqueue item is
used to maintain a minimum number of empty pages. In certain scenarios,
such as reported in [1], it is possible that physical memory becomes
quite scarce which can result in either a rather long time spent trying
to find free pages or worse, a kernel panic.

This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them
through to the underlying allocators. This should prevent any
unnecessary panics potentially caused by the workqueue item. The passing
of gfp around is as additional flags rather than a full set of flags.
The next patch will change these to caller passed semantics.

V2:
Added const modifier to gfp flags in the balance path.
Removed an extra whitespace.

[1] https://lkml.org/lkml/2018/2/12/551

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-08 14:26:29 +02:00
Documentation iio: ABI: Fix name of timestamp sysfs file 2018-03-28 18:24:49 +02:00
arch powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs 2018-04-08 14:26:28 +02:00
block partitions/msdos: Unable to mount UFS 44bsd partitions 2018-04-08 14:26:28 +02:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: ecc - Fix NULL pointer deref. on no default_rng 2018-03-19 08:42:49 +01:00
drivers RDMA/ucma: Introduce safer rdma_addr_size() variants 2018-04-08 14:26:29 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs ceph: only dirty ITER_IOVEC pages for direct read 2018-04-08 14:26:27 +02:00
include RDMA/ucma: Introduce safer rdma_addr_size() variants 2018-04-08 14:26:29 +02:00
init kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2018-02-22 15:42:23 +01:00
ipc ipc/shm.c: add split function to shm_vm_ops 2018-04-08 14:26:27 +02:00
kernel perf/hwbp: Simplify the perf-hwbp code, fix documentation 2018-04-08 14:26:27 +02:00
lib rhashtable: Fix rhlist duplicates insertion 2018-03-31 18:10:40 +02:00
mm percpu: add __GFP_NORETRY semantics to the percpu balancing path 2018-04-08 14:26:29 +02:00
net xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems 2018-04-08 14:26:29 +02:00
samples samples/bpf: adjust rlimit RLIMIT_MEMLOCK for xdp1 2017-12-20 10:10:31 +01:00
scripts kbuild: fix linker feature test macros when cross compiling with Clang 2018-03-24 11:01:29 +01:00
security /dev/mem: Add bounce buffer for copy-out 2018-03-24 11:01:24 +01:00
sound ALSA: pcm: potential uninitialized return values 2018-04-08 14:26:27 +02:00
tools x86/pkeys/selftests: Rename 'si_pkey' to 'siginfo_pkey' 2018-03-28 18:24:50 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: vgic: Don't populate multiple LRs with the same vintid 2018-03-21 12:06:43 +01:00
.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: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.32 2018-03-31 18:10:43 +02:00
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.