]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM
authorTony Battersby <tonyb@cybernetics.com>
Wed, 4 Feb 2009 23:12:04 +0000 (15:12 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 5 Feb 2009 20:56:47 +0000 (12:56 -0800)
commita68e61e8ff2d46327a37b69056998b47745db6fa
tree2445097933785b26d91577e6f4b41329e8bcd639
parent1f5e31d7e55ac7fbd4ec5e5b20c8868b0e4564c9
shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM

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>
Cc: <stable@kernel.org> [2.6.everything]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ipc/shm.c