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Josef Bacik 23b5ec7494 btrfs: fix readdir deadlock with pagefault
Readdir does dir_emit while under the btree lock.  dir_emit can trigger
the page fault which means we can deadlock.  Fix this by allocating a
buffer on opening a directory and copying the readdir into this buffer
and doing dir_emit from outside of the tree lock.

Thread A
readdir  <holding tree lock>
  dir_emit
    <page fault>
      down_read(mmap_sem)

Thread B
mmap write
  down_write(mmap_sem)
    page_mkwrite
      wait_ordered_extents

Process C
finish_ordered_extent
  insert_reserved_file_extent
   try to lock leaf <hang>

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ copy the deadlock scenario to changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2017-08-16 16:12:05 +02:00
arch Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2017-08-13 15:34:28 -07:00
block
certs
crypto
Documentation
drivers driver core fixes for 4.13-rc5 2017-08-13 12:44:18 -07:00
firmware
fs btrfs: fix readdir deadlock with pagefault 2017-08-16 16:12:05 +02:00
include btrfs: Remove redundant argument of flush_space 2017-08-16 16:12:01 +02:00
init
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usr
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Makefile Linux 4.13-rc5 2017-08-13 16:01:32 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.