The patch titled
shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM
has been added to the -mm tree. Its filename is
shm-fix-shmctlshm_info-lockup-with-config_shmem.patch
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------------------------------------------------------
Subject: shm: fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM
From: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Reported-by: Jiri Olsa <olsajiri@xxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx> [2.6.everything]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/shm.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN ipc/shm.c~shm-fix-shmctlshm_info-lockup-with-config_shmem ipc/shm.c
--- a/ipc/shm.c~shm-fix-shmctlshm_info-lockup-with-config_shmem
+++ a/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++;
_
Patches currently in -mm which might be from tonyb@xxxxxxxxxxxxxxx are
linux-next.patch
dmar-fix-endless-unknown-dmar-structure-type-loop.patch
shm-fix-shmctlshm_info-lockup-with-config_shmem.patch
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