Matthew Wilcox 90a32d1f0e mm/filemap.c: fix NULL pointer in page_cache_tree_insert()
commit abc1be13fd113ddef5e2d807a466286b864caed3 upstream.

f2fs specifies the __GFP_ZERO flag for allocating some of its pages.
Unfortunately, the page cache also uses the mapping's GFP flags for
allocating radix tree nodes.  It always masked off the __GFP_HIGHMEM
flag, and masks off __GFP_ZERO in some paths, but not all.  That causes
radix tree nodes to be allocated with a NULL list_head, which causes
backtraces like:

  __list_del_entry+0x30/0xd0
  list_lru_del+0xac/0x1ac
  page_cache_tree_insert+0xd8/0x110

The __GFP_DMA and __GFP_DMA32 flags would also be able to sneak through
if they are ever used.  Fix them all by using GFP_RECLAIM_MASK at the
innermost location, and remove it from earlier in the callchain.

Link: http://lkml.kernel.org/r/20180411060320.14458-2-willy@infradead.org
Fixes: 449dd6984d0e ("mm: keep page cache radix tree nodes in check")
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reported-by: Chris Fries <cfries@google.com>
Debugged-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24 09:36:39 +02:00
2018-04-24 09:36:38 +02:00
2018-04-19 08:56:21 +02:00

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.
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