Messages in this thread Patch in this message | | | Date | Tue, 27 Jan 2009 17:47:04 -0500 | From | Tony Battersby <> | Subject | [PATCH 1/2] 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.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com> CC: <stable@kernel.org> ---
This bug was reported by Jiri Olsa back in February 2008; CC'ing the people involved in the original discussion. http://lkml.org/lkml/2008/2/29/74
--- linux-2.6.29-rc2-git3/ipc/shm.c.orig 2009-01-27 16:23:10.000000000 -0500 +++ linux-2.6.29-rc2-git3/ipc/shm.c 2009-01-27 16:23:32.000000000 -0500 @@ -565,11 +565,15 @@ static void shm_get_stat(struct ipc_name struct hstate *h = hstate_file(shp->shm_file); *rss += pages_per_huge_page(h) * mapping->nrpages; } else { +#ifdef CONFIG_SHMEM struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); *rss += inode->i_mapping->nrpages; *swp += info->swapped; spin_unlock(&info->lock); +#else + *rss += inode->i_mapping->nrpages; +#endif } total++;
| |