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Filename Latest commit message Latest commit date
Vincent Donnefort 8928e31a77 sched/core: Mitigate race cpus_share_cache()/update_top_cache_domain()
[ Upstream commit 42dc938a590c96eeb429e1830123fef2366d9c80 ]

Nothing protects the access to the per_cpu variable sd_llc_id. When testing
the same CPU (i.e. this_cpu == that_cpu), a race condition exists with
update_top_cache_domain(). One scenario being:

              CPU1                            CPU2
  ==================================================================

  per_cpu(sd_llc_id, CPUX) => 0
                                    partition_sched_domains_locked()
      				      detach_destroy_domains()
  cpus_share_cache(CPUX, CPUX)          update_top_cache_domain(CPUX)
    per_cpu(sd_llc_id, CPUX) => 0
                                          per_cpu(sd_llc_id, CPUX) = CPUX
    per_cpu(sd_llc_id, CPUX) => CPUX
    return false

ttwu_queue_cond() wouldn't catch smp_processor_id() == cpu and the result
is a warning triggered from ttwu_queue_wakelist().

Avoid a such race in cpus_share_cache() by always returning true when
this_cpu == that_cpu.

Fixes: 518cd62341 ("sched: Only queue remote wakeups when crossing cache boundaries")
Reported-by: Jing-Ting Wu <jing-ting.wu@mediatek.com>
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20211104175120.857087-1-vincent.donnefort@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-26 10:47:17 +01:00
arch mips: BCM63XX: ensure that CPU_SUPPORTS_32BIT_KERNEL is set 2021-11-26 10:47:17 +01:00
block block: remove inaccurate requeue check 2021-11-17 09:48:31 +01:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:47:29 +02:00
crypto crypto: pcrypt - Delay write to padata->info 2021-11-17 09:48:40 +01:00
Documentation xen/balloon: add late_initcall_sync() for initial ballooning done 2021-11-17 09:48:25 +01:00
drivers clk: qcom: gcc-msm8996: Drop (again) gcc_aggre1_pnoc_ahb_clk 2021-11-26 10:47:17 +01:00
fs erofs: fix unsafe pagevec reuse of hooked pclusters 2021-11-21 13:38:51 +01:00
include f2fs: fix up f2fs_lookup tracepoints 2021-11-26 10:47:17 +01:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc
kernel sched/core: Mitigate race cpus_share_cache()/update_top_cache_domain() 2021-11-26 10:47:17 +01:00
lib lib/xz: Validate the value before assigning it to an enum variable 2021-11-17 09:48:31 +01:00
LICENSES
mm mm, oom: do not trigger out_of_memory from the #PF 2021-11-17 09:48:50 +01:00
net SUNRPC: Partial revert of commit 6f9f17287e78 2021-11-17 09:48:50 +01:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts leaking_addresses: Always print a trailing newline 2021-11-17 09:48:31 +01:00
security fortify: Explicitly disable Clang support 2021-11-21 13:38:50 +01:00
sound ALSA: gus: fix null pointer dereference on pointer block 2021-11-26 10:47:16 +01:00
tools selftests/bpf: Fix also no-alu32 strobemeta selftest 2021-11-17 09:48:51 +01:00
usr
virt KVM: do not shrink halt_poll_ns below grow_start 2021-10-09 14:39:50 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
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Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.161 2021-11-21 13:38:51 +01:00
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.

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.