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fcb170a9d8
The 'queue->nr' will wraparound from 0 to 255 when only current priority queue has tasks. This maybe lead a deadlock same as commitdfe1fe75e0("NFSv4: Fix deadlock between nfs4_evict_inode() and nfs4_opendata_get_inode()"): Privileged delegreturn task is queued to privileged list because all the slots are assigned. When non-privileged task complete and release the slot, a non-privileged maybe picked out. It maybe allocate slot failed when the session on draining. If the 'queue->nr' has wraparound to 255, and no enough slot to service it, then the privileged delegreturn will lost to wake up. So we should avoid the wraparound on 'queue->nr'. Reported-by: Hulk Robot <hulkci@huawei.com> Fixes:5fcdfacc01("NFSv4: Return delegations synchronously in evict_inode") Fixes:1da177e4c3("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
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.