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10c12851a0
The vmalloc allocator doesn't fully respect the specified gfp mask: while the actual pages are allocated as requested, the page table pages are always allocated with GFP_KERNEL. ceph_kvmalloc() may be called with GFP_NOFS and GFP_NOIO (for ceph and rbd respectively), so this may result in a deadlock. There is no real reason for the current PAGE_ALLOC_COSTLY_ORDER logic, it's just something that seemed sensible at the time (ceph_kvmalloc() predates kvmalloc()). kvmalloc() is smarter: in an attempt to reduce long term fragmentation, it first tries to kmalloc non-disruptively. Switch to kvmalloc() and set the respective PF_MEMALLOC_* flag using the scope API to avoid the deadlock. Note that kvmalloc() needs to be passed GFP_KERNEL to enable the fallback. Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Jeff Layton <jlayton@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.