Messages in this thread Patch in this message | | | Date | Tue, 10 Feb 2009 16:24:41 -0800 | From | Greg KH <> | Subject | [patch 13/56] shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM |
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2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------
From: Tony Battersby <tonyb@cybernetics.com>
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>
--- ipc/shm.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/ipc/shm.c +++ b/ipc/shm.c @@ -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++;
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