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Ming Lei 0263f92fad lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly
group_cpus_evenly() could be part of storage driver's error handler, such
as nvme driver, when may happen during CPU hotplug, in which storage queue
has to drain its pending IOs because all CPUs associated with the queue
are offline and the queue is becoming inactive.  And handling IO needs
error handler to provide forward progress.

Then deadlock is caused:

1) inside CPU hotplug handler, CPU hotplug lock is held, and blk-mq's
   handler is waiting for inflight IO

2) error handler is waiting for CPU hotplug lock

3) inflight IO can't be completed in blk-mq's CPU hotplug handler
   because error handling can't provide forward progress.

Solve the deadlock by not holding CPU hotplug lock in group_cpus_evenly(),
in which two stage spreads are taken: 1) the 1st stage is over all present
CPUs; 2) the end stage is over all other CPUs.

Turns out the two stage spread just needs consistent 'cpu_present_mask',
and remove the CPU hotplug lock by storing it into one local cache.  This
way doesn't change correctness, because all CPUs are still covered.

Link: https://lkml.kernel.org/r/20231120083559.285174-1-ming.lei@redhat.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Reported-by: Guangwu Zhang <guazhang@redhat.com>
Tested-by: Guangwu Zhang <guazhang@redhat.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <kbusch@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-06 16:12:46 -08:00
arch LoongArch fixes for v6.7-rc3 2023-11-22 10:20:17 -08:00
block vfs-6.7-rc3.fixes 2023-11-24 09:45:40 -08:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation Including fixes from bpf. 2023-11-23 10:40:13 -08:00
drivers mm/memory_hotplug: add missing mem_hotplug_lock 2023-12-06 16:12:46 -08:00
fs squashfs: squashfs_read_data need to check if the length is 0 2023-12-06 16:12:45 -08:00
include hugetlb: fix null-ptr-deref in hugetlb_vma_lock_write 2023-12-06 16:12:43 -08:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring: fix off-by one bvec index 2023-11-20 15:21:38 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel Including fixes from bpf. 2023-11-23 10:40:13 -08:00
lib lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly 2023-12-06 16:12:46 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/memory_hotplug: fix error handling in add_memory_resource() 2023-12-06 16:12:46 -08:00
net tls: fix NULL deref on tls_sw_splice_eof() with empty record 2023-11-23 08:51:45 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts checkstack: fix printed address 2023-12-06 16:12:46 -08:00
security + Features 2023-11-03 09:48:17 -10:00
sound sound fixes for 6.7-rc2 2023-11-17 09:05:31 -05:00
tools mm/selftests: fix pagemap_ioctl memory map test 2023-12-06 16:12:45 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap .mailmap: add a new address mapping for Chester Lin 2023-12-06 16:12:45 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Andrew Morton for lib/* 2023-12-06 16:12:43 -08:00
Makefile Linux 6.7-rc2 2023-11-19 15:02:14 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.