Paul E. McKenney a523031513 rcu: Use *_ONCE() to protect lockless ->expmask accesses
commit 15c7c972cd upstream.

The rcu_node structure's ->expmask field is accessed locklessly when
starting a new expedited grace period and when reporting an expedited
RCU CPU stall warning.  This commit therefore handles the former by
taking a snapshot of ->expmask while the lock is held and the latter
by applying READ_ONCE() to lockless reads and WRITE_ONCE() to the
corresponding updates.

Link: https://lore.kernel.org/lkml/CANpmjNNmSOagbTpffHr4=Yedckx9Rm2NuGqC9UqE+AOz5f1-ZQ@mail.gmail.com
Reported-by: syzbot+134336b86f728d6e55a0@syzkaller.appspotmail.com
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-11 04:35:08 -08:00
2020-02-05 21:22:47 +00:00
2020-02-05 21:22:53 +00:00

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

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    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.
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