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bd8a1f3655
For page splitting to succeed, the thread asking to split the page has to
be the only one with a reference to the page. Calling
wait_on_page_locked() while holding a reference to the page will
effectively prevent this from happening with sufficient threads waiting on
the same page. Use put_and_wait_on_page_locked() to sleep without holding
a reference to the page, then retry the page lookup after the page is
unlocked.
Since we now get the page lock a little earlier in filemap_update_page(),
we can eliminate a number of duplicate checks. The original intent
(commit ebded02788b5 ("avoid unnecessary calls to lock_page when waiting
for IO to complete during a read")) behind getting the page lock later was
to avoid re-locking the page after it has been brought uptodate by another
thread. We still avoid that because we go through the normal lookup path
again after the winning thread has brought the page uptodate.
Link: https://lkml.kernel.org/r/20210122160140.223228-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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.