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Muchun Song
f4f451a16d
FSDAX page refcounts are 1-based, rather than 0-based: if refcount is
1, then the page is freed. The FSDAX pages can be pinned through GUP,
then they will be unpinned via unpin_user_page() using a folio variant
to put the page, however, folio variants did not consider this special
case, the result will be to miss a wakeup event (like the user of
__fuse_dax_break_layouts()). This results in a task being permanently
stuck in TASK_INTERRUPTIBLE state.
Since FSDAX pages are only possibly obtained by GUP users, so fix GUP
instead of folio_put() to lower overhead.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: d8ddc099c6 ("mm/gup: Add gup_put_folio()")
Signed-off-by: Muchun Song <[email protected]>
Suggested-by: Matthew Wilcox <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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.