]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
mm: xip fix fault vs sparse page invalidate race
authorNick Piggin <npiggin@suse.de>
Wed, 20 Aug 2008 21:09:20 +0000 (14:09 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 20 Aug 2008 22:40:32 +0000 (15:40 -0700)
commit538f8ea6c85232d00bfa5edd9ba85f16c01057c9
treec1a4a49c0c7f16b4fe8ec560137084bf556efc50
parent479db0bf408e65baa14d2a9821abfcbc0804b847
mm: xip fix fault vs sparse page invalidate race

XIP has a race between sparse pages being inserted into page tables, and
sparse pages being zapped when its time to put a non-sparse page in.

What can happen is that a process can be left with a dangling sparse page
in a MAP_SHARED mapping, while the rest of the world sees the non-sparse
version.  Ie.  data corruption.

Guard these operations with a seqlock, making fault-in-sparse-pages the
slowpath, and try-to-unmap-sparse-pages the fastpath.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jared Hulbert <jaredeh@gmail.com>
Acked-by: Carsten Otte <cotte@freenet.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/filemap_xip.c