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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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Jeff Layton
d0a8729fc1
[ Upstream commit62575e270f] Some messages sent by the MDS entail a session sequence number increment, and the MDS will drop certain types of requests on the floor when the sequence numbers don't match. In particular, a REQUEST_CLOSE message can cross with one of the sequence morphing messages from the MDS which can cause the client to stall, waiting for a response that will never come. Originally, this meant an up to 5s delay before the recurring workqueue job kicked in and resent the request, but a recent change made it so that the client would never resend, causing a 60s stall unmounting and sometimes a blockisting event. Add a new helper for incrementing the session sequence and then testing to see whether a REQUEST_CLOSE needs to be resent, and move the handling of CEPH_MDS_SESSION_CLOSING into that function. Change all of the bare sequence counter increments to use the new helper. Reorganize check_session_state with a switch statement. It should no longer be called when the session is CLOSING, so throw a warning if it ever is (but still handle that case sanely). [ idryomov: whitespace, pr_err() call fixup ] URL: https://tracker.ceph.com/issues/47563 Fixes:fa99677342("ceph: fix potential mdsc use-after-free crash") Reported-by: Patrick Donnelly <pdonnell@redhat.com> Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Xiubo Li <xiubli@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.