From: Tony Battersby <tonyb@cybernetics.com>
Date: Wed, 4 Feb 2009 23:12:04 +0000 (-0800)
Subject: shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM
X-Git-Tag: v2.6.27.16~44
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2bba098bf6965d597db52ba6e377413b4cc24086;p=pandora-kernel.git

shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM

commit a68e61e8ff2d46327a37b69056998b47745db6fa upstream.

shm_get_stat() assumes that the inode is a "struct shmem_inode_info",
which is incorrect for !CONFIG_SHMEM (see fs/ramfs/inode.c:
ramfs_get_inode() vs.  mm/shmem.c: shmem_get_inode()).

This bad assumption can cause shmctl(SHM_INFO) to lockup when
shm_get_stat() tries to spin_lock(&info->lock).  Users of !CONFIG_SHMEM
may encounter this lockup simply by invoking the 'ipcs' command.

Reported by Jiri Olsa back in February 2008:
http://lkml.org/lkml/2008/2/29/74

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Reported-by: Jiri Olsa <olsajiri@gmail.com>
Cc: Hugh Dickins <hugh@veritas.com>
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@suse.de>
---

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